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Antiviral & Infectious Disease

Abacavir and DHR Risk

Drug hypersensitivity reaction is an unexpected immune response that may be experienced after taking a medication. The symptoms may range from mild to severe or even life-threatening. This type of response is more likely with newer drugs which have not yet had all possible side-effects discovered.

Although this type of reaction may be rare, the seriousness of the symptoms cannot be ignored. New drugs may need to be removed from the market when such severe side-effects come to light. Why some drugs activate a drastic immune response is not fully understood. Research to discover how to predict, prevent, or control such symptoms will be useful to develop better drugs.

A recent study at the FDA attempted to gain some understanding of the hypersensitivity reaction. The work focused on abacavir, an anti-retroviral HIV drug, which is known to commonly induce such undesired reaction. The severe immune response sometimes experienced with abacavir is known to be associated with a specific genetic variation, which is generally screened for prior to use.

In the lab, genetically altered mice were generated to produce the drug-hypersensitive variation. The mice were treated with abacavir for 8 days. Cellular and transcriptomic responses to the treatment were measured.

The research uncovered novel immune mechanisms driven by this molecule, related to inflammatory triggers involving Treg cells and CD4+ cells. Critical pathways that may be useful targets for therapy were identified in this study. Further research and understanding of these targets will help to prevent and manage the severe drug hypersensitivity reactions. This will reduce the risk and increase the benefit of drugs with this side-effect.

Cardone M, Baghdassarian H, Khalaj M, et al. Insights into regulatory T-cell and type-I interferon roles in determining abacavir-induced hypersensitivity or immune tolerance. Front Immunol. 2025 Jun 6:16:1612451. PMID: 40547023

Thapsigargin Antiviral Potential

Thapsigargin is a natural chemical found in the plant Thapsia garganica, a flowering perennial in the carrot family. One response to the COVID-19 pandemic was intense exploration for new antivirals. The antiviral activity of thapsigargin was consequently reassessed and demonstrated broad-spectrum antiviral effects.

While it did not become one of the go-to drugs for COVID infections, the global pig industry also suffers the effects of several coronaviruses, so it could have potential use there. In addition to the loss of marketable animals and financial hardships, there is always the risk of cross-species transmission leading to human infection. The unceasing emergence of mutant strains puts limitations on the effectiveness of the available vaccines. Therefore, the use of antiviral drugs in combination with vaccinations has become the go-to strategy to increase the survival rate of the animals.

To assess the effect of thapsigargin for the pig industry, the porcine coronavirus known as transmissible gastroenteritis virus (TGEV) was chosen. Piglets were first orally infected with the TGEV virus, then given thapsigargin at 1 hour and 12 hours post-infection. The animals were checked at 0, 12, and 24 hours post-infection for viral shedding. After 24 hours, the animals were euthanized and the intestinal tissues were collected and evaluated.

The results of the tissue tests showed that the infection was suppressed by the thapsigargin treatment. However, there were also concerning signs of the impact of side effects on the gastrointestinal mucosa. While this compound certainly shows potential for controlling viral infections, further evaluation should be undertaken to improve our understanding.

Li Y, Liu Y, Zhang Y, et al. In vitro and in vivo evaluation of thapsigargin as an antiviral agent against transmissible gastroenteritis virus. Vet Res. 2024 Aug 2;55(1):97. PMID: 39095890

Drug Repurposing for Viral Variants

Drug repurposing for viral variants may prove to be an efficient means to combat the mutating of COVID-19. As vaccine-resistant variants emerge, many patients with comorbidities require hospitalization due to sever complications. The fastest and cheapest route to discovering a new treatment is to check if any of the existing approved drugs are effective against COVID.

The search begins…

Recently, the FDA-approved drugs library was used for this purpose. To begin, first a simulation of each drug molecule docking with SARS-CoV-2 spike receptor-binding domain was run. The database contained around 2,500 drugs.

The spike receptor-binding domain was chosen for the simulation because it is already known that this domain plays a significant role in the entry of the virus into the host cell. The primary goal of this study is to find a drug that can impede the entry point, and thereby prevent infection from even beginning.

From the library of 2,500 drugs, 20 showed good results with the simulation and relatively high safety profiles. These 20 were carried on for further validation in the lab using a binding assay kit. The assay kit was also specific for the SARS-CoV-2 spike binding.

From the binding assay, 5 of the molecules continued to show promise as they consistently and significantly inhibit the binding of SARS-CoV-2 and the receptor. These 5 were carried on with in vitro work using Vero E6 cells. Each molecule was assessed for the required concentration and toxic concentration.

And then there were 3…

From the 5 molecules, 3 of them continued to show promise against SARS-CoV-2. These 3: argatroban, ranolazine, and glimepiride had a high selectivity index, and most interestingly, they each impacted different stages of the viral life cycle. Argatroban induced a direct virucidal effect; glimepiride inhibited viral replication; ranolazine inhibited viral adsorption onto the host cell.

This project has successfully identified 3 high-potential candidates for drug repurposing by weeding through the library of 2,500 already approved drugs. Further testing must also be done to develop the most safe and effective dosing, formulation, and potentially combination therapies to continue combating the new COVID variants.

Sobky S, Fawzy I, Ahmed M, et al. Drug repurposing of argatroban, glimepiride, and ranolazine shows anti-SARS-CoV-2 activity via diverse mechanisms. Heliyon. 2025 Jan 10;11(3):e41894. PMID: 39968139

PF-07321332 D48N Mutant Inhibitor

PF-07321332 is an active ingredient in Paxlovid, which is a treatment for COVID-19. This molecule inhibits the activity of the main protease of the virus SARS-CoV-2. This main protease is responsible for producing 12 functional proteins which are highly conserved across several coronaviruses. This includes several of the well-known COVID-19 variants.

Finding a treatment that can remain effective against various mutant varieties as well as the wild-type is key to combating this virus. Recently, the D48N mutant was investigated in comparison to the wild-type for effectiveness of the treatment. The D48N mutant contains a single amino acid substitution near the main protease active site. This substitution has already been confirmed to exist in several COVID-19 variants.

To begin the study, first the D48N mutant was cultured and purified. The next step was to run enzymatic inhibition assays to test the inhibitory activities of both shikonin and PF-07321332. Shikonin was also included in the test because the research team’s previous work shows that it also appears to be promising for main protease inhibition.

Next, the purified D48N was mixed together with either of these molecules and allowed time to bond, resulting in the formation of a complex. The complex was then crystallized and the crystals collected for examination. By this method the structures of the complexes can be determined and the interaction of the molecule with D48N confirmed.

The results showed that both PF-07321332 and shikonin have potent inhibitory effects against both D48N mutant and wild-type main protease. Interestingly, shikonin demonstrated non-covalent binding while PF-07321332 demonstrated covalent binding. The data from this study may be useful in further work to develop additional treatments for COVID-19.

Zhao Z, Zhu Q, Zhou X, et al. Structural basis for the inhibition of SARS-CoV-2 Mpro D48N mutant by shikonin and PF-07321332. Viruses. 2023 Dec 30;16(1):65. PMID: 38257765

Virginiamycin in Livestock Feed

Virginiamycin is commonly used in livestock as a growth promoter. In the final stage of cattle farming, the dietary components of the feedlot are adjusted to produce the best quality meat. This generally involves increasing the amount of fat in the animal. In most cases, the final stage diet is grain-based, rather than grass. During this stage, additives such as virginiamycin are also introduced.

Virginiamycin is a macrolide antibiotic which has repeatedly been shown to improve animal performance. However, it is unclear whether it works by protecting the liver, or impacting the short-chain fatty acid profile in the rumen, or improving the protein flow to the small intestine.

Recently, a study at Texas A&M evaluated the effects of this additive in an attempt to understand exactly how it works. The animals were treated with 3 different dosage levels for comparison. After treatment, samples of rumen fluid, feces, and urine were collected and analyzed.

The results from this study found that virginiamycin supplementation did not effect nutrient digestibility but did increase ruminal pH and impacted the rumen dynamics. It also seemed to improve the protein flow to the small intestine.

Additional research should be done to further understand the impact of virginiamycin supplementation on the bacteria population and fermentation in the rumen. Laboratory reference standards for specific virginiamycins are available at LKT Labs:

Virginiamycin M1

Virginiamycin S1

Virginiamycin Mixture (M1 & S1)

Batista L, Rivera M, Fonseca M, et al. The influence of virginiamycin on digestion and ruminal parameters under feedlot conditions. Transl Anim Sci. 2024 Feb 14:8:txae019. PMID: 38406320

VSV Molecular Switch

Vesicular stomatitis virus (VSV) is a disease that primarily effects horses, cattle, and swine. Humans can contract this disease by coming in contact with an infected animal. The disease is most often found in North America and Central America. In humans, the symptoms are similar to a flu. The virus replicates quickly and its genome is small and easy to manipulate. Because of this, it has become a useful research tool, as a vaccine platform, and as an oncolytic vector.

There are multiple methods in use to modify viruses such as this. The most important factor in controlling the virus and putting it to use is to have control over the viruses natural ability to replicate. One method to take control over replication is the use of intein splicing. Intein splicing is often a spontaneous biochemical reaction, however, previous research has developed inteins that only undergo splicing in the presence of 4-hydroxytamoxifen.

In vitro Testing

In this way, 4-hydroxytamoxifen can be used as a molecular switch to either prevent or allow splicing to occur. This idea was tested by a team of researchers at Beijing Institute of Biotechnology. After first screening for the most effective intein insertion site, the in vitro replication regulation of the modified virus was assessed. They confirmed that the presence or absence of 4-hydroxytamoxifen directly controlled the replication ability.

In vivo Testing

After seeing the positive results in vitro, they then continued the research in vivo. Laboratory mice were first injected intracerebrally with the modified virus and then also injected intraperitoneally with 4-hydroxytamoxifen. The progression of this experiment was measured using luminescence imaging of the brain. They confirmed that the virus was still controlled in vivo.

This is an exciting improvement in manipulating and controlling a virus so that it may be used as a tool in biological systems. The same idea applied to vesicular stomatitis virus may also be useful in working with various other viruses too.

4-Hydroxytamoxifen is available at LKT Labs:

(E/Z)-4-Hydroxytamoxifen

(E)-4-Hydroxytamoxifen

(Z)-4-Hydroxytamoxifen

Zhao Z, Wang B, Wu S, et al. Regulated control of virus replication by 4-hydroxytamoxifen-induced splicing. Front Microbiol. 2023 Mar 13:14:1112580. doi: 10.3389/fmicb.2023.1112580. PMID: 36992923

 

Joint Replacement Infection Antibiotics

Joint replacement surgery is a common approach to treating severe joint pain or dysfunction that does not respond to less invasive therapy. Successful surgery offers improved quality of life with decreased pain and improved mobility. However, this treatment also comes with the risk of joint infection, and treatment of such an infection may not be straightforward.

New antibiotics and new combinations of antibiotics are necessary to deal with the antibiotic resistance that bacteria develop over time.

Lab Imitation of Joint Replacement

A study to mimic a joint replacement followed by infection has been carried out. In the animal lab, Wistar rats were implanted with a rod into the thigh bone. The rod was made of sterile steel and was infected with a bacterial suspension before being implanted. Two different kinds of bacteria suspension were tested.

Antibiotics Treatments Attempted

Treatment with antibiotics started seven days after the surgery. The antibiotics that were tested individually include linezolid, vancomycin, rifampin, and cotrimoxazole. A few antibiotic combinations were also tested: 1. rifampin + linezolid, 2. rifampin + vancomycin, and 3. rifampin + cotrimoxazole. After 23 days, the implants were removed, and the bacterial counts of the implant and surrounding tissues examined.

Joint Infection Under Control

In this study, rifampin is the only antibiotic to significantly reduce the bacterial infection on its own. However, it is already known that monotherapy using rifampin is not a good option. Previous studies found frequent development of resistance to treatment when only rifampin is used. An effective treatment needs to also prevent these resistance mechanisms from forming or evolving.

As it turns out, the combination antibiotic treatments used in this study were also found to be effective. And in addition, the combination treatment significantly reduced the development of resistance.

A Real Concern

Infection after joint replacement surgery is rare for a first-time surgery. However, if repeated surgeries are required, the risk of infection is significant. And since replaced joints typically last only 10-25 years, many people eventually require a second and third or more replacement surgeries. Therefore, it is important to determine an effective method of treatment for this type of infection.

Goetz J, Keyssner V, Hanses F, et al. Animal experimental investigation on the efficacy of antibiotic therapy with linezolid, vancomycin, cotrimoxazole, and rifampin in treatment of periprosthetic knee joint infections by MSRA. Bone Joint Res. 2022 Mar;11(3):143-151. doi:10.1302/2046-3758. PMID: 35227086

Telacebec, an Emerging Antibiotic

Telacebec is an emerging antibiotic. It’s part of a new class of antibiotics that disrupt the electron transport chain, which could be used to treat drug-resistant tuberculosis. Telacebec also has the potential to treat diseases closely related to tuberculosis, such as leprosy and Buruli ulcer. The Buruli ulcer pathogen, Mycobacterium ulcerans, is especially sensitive to telacebec.

Buruli Ulcer

Buruli ulcer is a neglected tropical disease that causes open wounds on the arms and legs. The standard of care is an eight-week-long course of antibiotics, which is difficult to give in resource-poor settings. Recently, a research team wanted to see if telacebec could be used as a shorter treatment.

Experimental Model

They infected mouse footpads with Mycobacterium ulcerans, then gave the mice a range of doses of telacebec. These treatments were more effective than standard antibiotics, and cleared infection after five days of treatment, or even in some cases after a single dose.

Mouse footpads continued to improve even after the treatment was stopped. We know that Mycobacterium ulcerans knocks down the immune system in infected limbs. Telacebec treatment might restore the immune system, which then clears the infection. To test this hypothesis, the researchers repeated their experiment in immunocompromised mice. These mice didn’t respond to treatment as well as normal mice.

A Word of Caution

Telacebec shows great promise for improving the treatment of Buruli ulcer, but short course, monotherapy treatments such as this one risk causing antibiotic resistance. Furthermore, doctors should use extra care with immunocompromised patients, such as people with HIV. For these people it might be safer to use a longer course of treatment or to use telacebec as part of an antibiotic cocktail.

Komm O, Almeida DV, Converse PJ, et al. Impact of dose, duration, and immune status on efficacy of ultrashort telacebec regimens in mouse models of Buruli ulcer. Antimicrobial Agents Chemotherapy. 2021 Oct 18,65(11):e0141821. doi: 10.1128/AAC.01418-21  PMID: 34460302

Nirmatrelvir Against SARS-CoV-2 Mutants

SARS-CoV-2 continues to cause death and illness across the world. We need both vaccines and an arsenal of antiviral drugs to combat this virus.

One drug that was recently developed to treat SARS-CoV-2 is nirmatrelvir. Nirmatrelvir targets the main protease (Mpro) of SARS-CoV-2, which it needs to replicate. This molecule binds to the active site of Mpro and permanently alters it.

A recent study by Ullrich et al. sought to test whether nirmatrelvir still works when SARS-CoV-2 accumulates mutations in its Mpro. Epidemiologists have identified many mutations in this protease, so Ullrich et al. chose a selection of the most common mutations to study. They expressed mutant copies of Mpro and measured their proteolytic activity. The mutant Mpro has similar activity to wild-type.

Next, the researchers added nirmatrelvir to the mutant Mpro and calculated its inhibitory concentration. Nirmatrelvir inhibitory concentration against the mutant Mpro was similar to the wild-type.

This encouraging result suggests that nirmatrelvir will continue to work against SARS-CoV-2 in the near future, even if the virus mutates. However, in the long term we should consider developing drug cocktails to prevent resistance from evolving.

 

Ullrich S, Ekanayake KB, Otting G, Nitsche C. Main protease mutants of SARS-CoV-2 variants remain susceptible to nirmatrelvir. Bioorg Med Chem Lett. 2022 Apr 15;62:128629. doi.org/10.1016/j.bmcl.2022.128629. PMID: 35182772

Mayaro Virus Antiviral EIDD-1931

Mayaro virus is a mosquito-borne virus endemic to forests in South America. It causes acute illness with fever, headache, rash, and long-lasting joint pain. Mayaro’s range could spread in the future because of climate change. No vaccines or antiviral drugs are currently available although there are some candidates under development.

Therefore, a concerned team of scientists from the Rega Institute for Medical Researchin Belgium wanted to do exploratory research on antivirals that might treat this disease. They chose a panel of molecules that are known to treat other mosquito-borne viruses, some of which block early stages of the virus life cycle (arbidol, chloroquine, suramin, and ribavirin), and some that inhibit virus genome replication (favipiravir, 7DMA, 2’CMC, EIDD-1931, galidesivir and remdesivir).

They then applied these selected molecules to a model of cell culture that was infected with Mayaro virus. The researchers measured the 50% effective concentration, or the amount of molecule that inhibits 50% of the virus infectivity. They optimized the antiviral screening assay to be reproducible and reliable.

The assay described in this paper can be useful to test future antiviral drugs against this virus. Furthermore, the three molecules that performed well in cell culture are worth further study with in vivo models. Although the range of Mayaro virus is limited for now, we should study it and other neglected diseases to proactively prevent suffering in the future.

 

Langendries L, Abdelnabi R, Neyts J, Delang L. Repurposing drugs for Mayaro virus: identification of EIDD-1931, Favipiravir, and Suramin as Mayaro virus inhibitors. Microorganisms. 2021 Mar 31;9(4):734. PMID: 33807492

Molnupiravir Against COVID-19

Molnupiravir is an antiviral drug that has recently been approved by the FDA for the treatment of COVID-19. This drug is especially exciting because it is the first approved COVID-19 drug that can be taken as a pill, and also because it reduces the risk of hospitalization and death by 30%. Two recent research papers give us insight into the molecular biology of how molnupiravir works.

In order to reproduce, the virus SARS-CoV-2 needs to synthesize RNA. Usually, the enzyme it uses to do this, RNA-dependent RNA polymerase (RdRp), is an attractive target for makers of antiviral drugs. At present, many antiviral drugs block RdRp by mimicking RNA nucleotides. When such a drug gets incorporated into a new RNA strand, synthesis stops. Unfortunately, this drug strategy is not effective against SARS-CoV-2 because it has proofreading enzymes that allow synthesis to continue.

Two research teams in Germany and Canada recently showed that molnupiravir mimics cytidine and uridine, two RNA nucleotides. Molnupiravir incorporates into new RNA strands, like other antiviral drugs. But interestingly, RdRp continues to synthesize RNA. How, then, does molnupiravir prevent severe COVID-19?

Both teams addressed this question by combining RNA that contained molnupiravir with RdRp in vitro. They found that when RdRp uses this RNA to synthesize new RNA, molnupiravir causes mutations. After several generations, mutations build up to a lethal level and the virus can no longer reproduce.

Molnupiravir’s mechanism of action evades viral proofreading enzymes. Because of this, it may also find use in treating a broad variety of other viruses that also have these enzymes.

 

Kabinger F, Stiller C, Schmitzova J, et al. Mechanism of molnupiravir-induced SARS-CoV-2 mutagenesis. Nature Structural & Molecular Biology. 2021 Sep;28(9):740-746. PMID: 34381216

Gordon CJ, Tchesnokov EP, Schinazi RF, et al. Molnupiravir promotes SARS-CoV-2 mutagenesis via the RNA template. Journal of Biological Chemistry. 2021 Jul;297(1):100770. PMID: 33989635

FDA News Release: FDA authorizes additional oral antiviral for treatment of COVID-19 in certain adults

Fidaxomicin as a New Antibiotic Template

Fidaxomicin is a narrow-spectrum antibiotic that is specific against gram-positive bacteria. Furthermore, it is not well absorbed into the bloodstream, so it remains in the gut. Both these characteristics make it a useful drug to treat Clostridioides difficile infections. It has been in clinical use since 2011.

Fidaxomicin-resistant C. difficile is currently rare, but antibiotic resistance is always a concern. A team of scientists at the University of Zurich, Switzerland wanted to use fidaxomicin as a template to develop new antibiotics before more resistant strains evolve.

They used a rational design approach, starting with the cryo-EM structure of fidaxomicin bound to bacterial RNA polymerase. Fidaxomicin has two carbohydrates attached to it, a noviose and a rhamnose. Based on the cryo-EM structure, the C3″ on the noviose looked like a promising place to add new functional groups. The team made thirty derivatives of fidaxomicin by changing the functional groups on that carbon.

They tested the antibiotic activity of these derivatives by measuring their minimal inhibitory concentration against C. difficile. Many of the derivatives still showed antibiotic activity. Although the derivatives were not any more effective against C. difficile than fidaxomicin, this experiment is an encouraging proof of concept for the rational design of new antibiotics.

 

Dailler D, Dorst A, Schafle D, et al. Novel fidaxomicin antibiotics through site-selective catalysis. Communications Chemistry. 2021. 4:59.  doi.org/10.1038/s42004-021-00501-6.

Protease Inhibitors: Saquinavir and Boceprevir

The COVID-19 pandemic continues to cause death and severe illness around the world. As many countries still experience vaccine shortages and the virus evolves to be more contagious, we need to develop better treatments for this disease.

A Possible Target:

The SARS-CoV2 main protease (Mpro) is an attractive target for drug treatment. The coronavirus needs this protease to process its proteins, an important step in its life cycle. Protease inhibitors are already in clinical use to treat other viral infections, such as HIV and hepatitis C. Repurposed existing drugs can get approval to treat disease faster than new drugs because their safety and pharmacokinetics are already known. Can we repurpose known protease inhibitors to treat SARS-CoV2 infection?

Two recent scientific studies address this question.

Docking and Molecular Dynamics Simulations:

Bello et al. built a computer model of Mpro and twelve promising protease inhibitors: darunavir, indinavir, saquinavir, tipranavir, diosmin, hesperidin, rutin, raltegravir, velpatasvir, ledipasvir, rosuvastatin, and bortezomib. The model predicts that of the twelve, saquinavir should bind to Mpro the best. Interestingly, saquinavir has long been used as part of drug cocktails to treat HIV. Although a computer study is limited, saquinavir is worth following up in vitro.

Enzyme Assays:

Another team of researchers, Ma et al., used an enzyme assay to screen for drugs that might inhibit the activity of Mpro. Out of a library of known inhibitors, they found that boceprevir inhibited Mpro the most. Formerly, boceprevir was used to treat hepatitis C before more effective protease inhibitors were developed. Boceprevir might find new life now as a treatment for COVID-19, and is worth further study.

 

Bello M, Martinez-Muñoz A, Balbuena-Rebolledo I. Identification of saquinavir as a potent inhibitor of dimeric SARS-CoV2 main protease through MM/GBSA. Journal of Molecular Modeling. 2020 Nov 12; 26(12):340. PMID: 33184722

Ma C, Sacco MC, Hurst B, et al. Boceprevir, GC-376, and calpain inhibitors II, XII inhibit SARS-CoV2 viral replication by targeting the viral main protease. Cell Research. 2020 Aug; 30(8):678-692. PMID: 32541865

Remdesivir Synergy Against COVID-19

Currently, remdesivir is the only antiviral drug approved to treat COVID-19. Its effects on the course of disease are moderate. Many viral diseases, such as HIV and hepatitis C, are treated with drug cocktails. Existing antiviral drugs might make remdesivir more effective in combination.

Two research teams recently screened for antiviral drugs that might increase the effectiveness of remdesivir.

Lo et al. screened a library of drugs for its ability to reduce SARS-CoV-2 viral load in kidney epithelial cells. They found that simeprevir reduces viral load in vitro. Simeprevir is a protease inhibitor that is often combined with sofosbuvir to treat hepatitis C. Simeprevir was even more effective in the in vitro experiment when combined with remdesivir.

Nguyenla et al. added remdesivir to cell cultures of kidney epithelial cells and human lung cells and infected these cells with SARS-CoV-2. They used this remdesivir-treated culture to screen a large library of FDA-approved drugs for compounds that reduce a proxy measure of viral load. The team chose the twenty most promising drugs to validate in human lung cell culture, which they tested for viral load.

The drugs velpatasvir and elbasvir reduced viral load. Both velpatasvir and elbasvir are used as parts of drug cocktails to treat hepatitis C. Velpatasvir is used with sofosbuvir and elbasvir is used with grazoprevir. The research team then tested the velpatasvir/sofosbuvir and elbasvir/grazoprevir cocktails with remdesivir in lung cell culture; the three-drug cocktails were even more effective that the pairs.

These results support the idea that COVID-19 could be better treated with cocktails of antiviral drugs.

 

Lo HS, Hui KPY, Lai HM, et al. Simeprevir potently suppresses SARS-CoV-2 replication and synergizes with remdesivir. ACS Central Science. 2021 May 26;7(5): 792-802. doi: 10.1021/acscentsci.0c01186. PMID: 34075346

Nguyenla X, Wehri E, Dis EV, et al. Discovery of SARS-CoV-2 antiviral synergy between remdesivir and approved drugs in human lung cells. BiorXiv. Preprint. 2020 Sept. http://doi.org/10.1101/2020.09.18.302398

Baloxavir Antiviral to Shorten and Prevent Influenza

Baloxavir is an antiviral drug that was FDA approved in 2018 for the treatment of influenza. It works by inhibiting an enzyme that influenza needs to replicate its DNA. When taken early, it can shorten the course of influenza by a day.

But can it also prevent influenza?

Researchers working for Shionogi, the manufacturer of baloxavir, set up a clinical trial in Japan to test this question. During the 2018-2019 flu season, they identified patients with influenza when they went to see their primary care doctor.

The researchers offered the household contacts of these patients either baloxavir or a placebo. Ten days later, the researchers tested the household contacts for influenza RNA (clinical influenza) using RT-PCR.

1.9% of household contacts who took the active treatment had clinical influenza whereas 13.6% of household contacts who took the placebo had clinical influenza. This is a successful demonstration that Baloxavir is effective at preventing influenza and as such was recently FDA approved for this use.

The authors of this study were not able to rule out whether this chemical can contribute to the rise of drug-resistant influenza. Further research is needed on this topic.

 

Baloxavir

Baloxavir Marboxil

 

Ikematsu H, Hayden FG, Kawaguchi K, et al. Baloxavir marboxil for prophylaxis against influenza in household contacts. N Engl J Med. 2020 Jul 23; 383(4):309-320. doi 10.1056/NEJMoa1915341. PMID: 32640124.

 

Lopinavir Antiretroviral Delivery Using NLC

Lopinavir is an antiretroviral drug that is important for the treatment of HIV. Unfortunately, it has a low bioavailability because it dissolves poorly in water.

The drug might be absorbed better if it was encased in a nanostructured lipid carrier (NLC). An NLC is a particle containing a mixture of solid and liquid lipids- which should deliver drugs better than solid-only lipid particles. Recently, researchers in Malaysia sought to do a proof-of-concept of an NLC to deliver lopinavir.

To determine optimal conditions for creating NLCs, they varied homogenization time and amounts of solid lipid, liquid lipid, and surfactant. They picked the most promising sets of conditions for further study.

The researchers tested the NLCs for drug release rate in simulated gastric fluid and in simulated intestinal fluid. The NLCs released drug better than straight lopinavir, which would not dissolve in either fluid. Next, they applied the NLCs to a cell line that is popular for studying intestinal epithelium. NLC lopinavir entered the cells faster than straight lopinavir.

Finally, the researchers fed an NLC lopinavir suspension to rats. The rats reached higher blood lopinavir concentrations than rats fed straight lopinavir.

Lopinavir is an antiretroviral drug with poor bioavailability. Nanostructured lipid carriers show potential for improved drug delivery of lopinavir.

Khan AA, Mudassir J, Akhtar S, et al. Freeze-dried lopinavir-loaded nanostructured lipid carriers for enhanced cellular uptake and bioavailability: statistical optimization, in vitro and in vivo evaluations. Pharmaceutics. 2019; 11(2):97. PMID: 30823545

Promising Mycobacteria Treatment: Bedaquiline

Bedaquiline, a potential treatment for several kinds of mycobacteria, was the first new drug to be approved for the treatment of tuberculosis in forty years back in 2012. This drug is especially important for the treatment of multidrug-resistant tuberculosis when first line treatments fail. It works by preventing the mycobacterium from making ATP, which is a different mechanism from older treatments.

Bedaquiline has attracted interest from public health researchers for the treatment of non-tuberculous mycobacteria. These bacteria infect lungs and wounds, especially in immunocompromised patients. In rich countries, non-tuberculous mycobacterial infections cause a greater health burden than tuberculosis itself does. These infections are difficult to treat because, as with tuberculosis, no effective drugs have been developed recently.

Researchers at the University of Texas Health Science Center have begun investigating the potential for developing a new treatment for this type of infection using bedaquiline. To begin, they first collected isolates of non-tuberculous mycobacteria from lungs and wounds of infected patients and grew them in nutrient broth. The isolates were then tested using broth microdilution antimicrobial susceptibility testing (AST). They calculated the minimum amount of bedaquiline they needed to add to the broth to inhibit bacterial growth, the minimum inhibitory concentration. They found that the required concentrations should be achievable in patients’ blood, so bedaquiline has potential to treat non-tuberculous mycobacterial infections.

In considering bedaquiline for the treatment of mycobacteria, researchers caution that bedaquiline should not be used as a monotherapy, because of the potential for bacteria to develop resistance.

 

Bedaquiline Fumarate

 

Brown-Elliot BA, Wallace RJ. 2018. In vitro susceptibility testing of bedaquiline against mycobacterium absceccus complex. Antimicrobial Agents and Chemotherapy. 29:63(2). doi: 10.1128/AAC.01919-18. PMID: 30509936

 

Now that you’ve read about it, find out how to pronounce it too!

 

Chemicals for Pharmaceutical Research for the Novel Coronavirus, COVID-19

The coronavirus known as COVID-19 first appeared in December, 2019 and spread around the world within a matter of days. As of this writing, it has infected nearly 400,000 people in 169 countries.

Scientists around the world have stopped their normal research to focus on creating a vaccine and treatment for this illness which has killed more than 17,000 people worldwide. Fortunately, more than 100,000 have recovered.

On March 22, 2020, an international team of scientists published a research paper preprint on biorXiv analyzing the interaction between the novel coronavirus and human proteins.* Their analysis predicts 332 protein-protein interactions and 69 existing pharmaceuticals that might perturb these interactions. The researchers propose that these drugs may be candidates for treating COVID-19 infections.

 LKT Laboratories has a number of these proposed chemicals for COVID-19 research in stock that can be shipped within 24 hours:

We also have various other antiviral compounds available:

See complete list of available antiviral compounds here

*A SARS-CoV-2-Human Protein-Protein Interaction Map Reveals Drug Targets and Potential Drug-Repurposing, David E. Gordon et al., bioRxiv 2020.03.22.002386; doi: https://doi.org/10.1101/2020.03.22.002386.

LKT Laboratories is a biochemical supply company focused on the synthesis, purification, and isolation of small molecules for research applications. All laboratory activities, including synthesis, natural product isolation, and full analytical characterization of our products are performed at our headquarters in St. Paul, MN.  Call or email us if you have questions about the chemicals above or have a need for other chemicals not listed.

Recombinant AMPs May Be More Effective Antibacterials

Background:

Antimicrobial peptides (AMPs) are short strings of amino acids, about 12-50 residues long, that show potent antibacterial, antiviral, and antifungal activity. They are found throughout the tree of life as part of the innate immune system. Many AMPs are in clinical use, such as vancomycin.

A class of AMPs called the cecropins were first isolated from the moth Hyalophora cecropia. Magainins were first isolated from the frog Xenopus laevis. An analog of magainin went through clinical trials as a treatment for infected diabetic foot ulcers, but failed.

Research Inspiration:

Researchers from the Jilin Agricultural University in China are interested in developing AMPs for livestock feed as an alternative to antibiotics. Previous research suggested that the fusion of peptides from two AMPs may enhance their antibacterial activity. Zhang et al. decided to test the properties of a magainin II – cecropin B fusion.

The group was also interested in testing whether the fungus Cordyceps militaris would make a suitable expression vehicle for fusion proteins. They constructed a plasmid that coded for the magainin II – cecropin B fusion and transformed cordyceps to express it. Then they extracted protein from the transformed fungus.

New Testing:

They tested the extract using ELISA, PAGE, and Western blotting and found that the cordyceps did express the fusion protein. Then, they swabbed the protein onto plates containing various species of bacteria to test whether it inhibited bacterial growth. Magainin II – cecropin B inhibited bacterial growth better than cecropin B alone.

The researchers also administered magainin II – cecropin B to mice infected with E. coli. The fusion inhibited E. coli growth in the mouse gut, and the mice suffered less intestinal damage. The same effect was observed when they fed the transformed cordyceps straight to the mice.

Zhang et al. conclude that magainin II – cecropin B is an effective antimicrobial. Cordyceps militaris that expresses magainin II – cecropin B could potentially be added to livestock feed.

 

C1609 Cecropin B
M0124 Magainin 1
M0126 Magainin 2

 

Zhang M, Shan Y, Gau H, Wang B, Liu X, Dong Y, Liu X, Yao N, Zhou Y, Li X, Li H. Expression of a recombinant hybrid antimicrobial peptide magainin II-cecropin B in the mycelium of the medicinal fungus Cordyceps militaris and its validation in mice. 2018. Microb Cell Fact. 17:18. PMID: 29402269.

Dietary Phytochemicals Exhibit Multiple Mechanisms of Action Against Pathogenic Bacteria

Isothiocyanates are a family of biologically active phytochemicals found naturally in cruciferous plants. They have been investigated for their antioxidative, anti-inflammatory, and anticancer effects. They have also shown activity against neurodegenerative diseases. Recently, their properties as antibacterial agents were investigated by Nowicki, et al.

Mechanisms for two isothiocyanates, sulforaphane and phenethyl isothiocyanate, were studied in multiple strains of bacteria.  These strains included clinical isolates of E. coli, K. pneumoniae, S. aureus, S. epidermidis, and E. faecalis. In strains where growth inhibition by isothiocyanates is independent of (p)ppGpp production, the inhibition of nucleic acid synthesis and cell viability may be due to a drop in GTP levels. In strains which do not produce (p)ppGpp upon treatment such as B. subtilis, the isothiocyanates compromise the integrity of the cytoplasmic membrane. They concluded that isothiocyanates likely have more than one target in bacterial cells, and that the mechanisms of action may be species-specific. Although the mechanisms change the resulting inhibition of bacterial growth is the same across multiple strains.

LKT Labs offers a wide variety of isothiocyanate molecules for research use.

 

S8044 R,S-Sulforaphane

E6880 Erucin

I0416 Iberin

I74571-Isothiocyanato-6-(methylsulfinyl)-hexane

Full List of ITCs

 

References:

Nowicki D., Maciag-Dorszynska M. et al. Various modes of action of dietary phytochemicals, sulforaphane and phenethyl isothiocyanate, on pathogenic bacteria. Sci Rep. 9(1):13677 (2019). doi: 10.1038/s41598-019-50216-x.