Influenza Virus Strains Research Articles

Preliminary evidence that daily light exposure enhances the antibody response to influenza vaccination in patients with dementia

Enhancing lighting conditions in institutions for individuals with dementia improves their sleep, circadian rhythms and well-being. Here, we report first findings that exposure to brighter light during daytime may support the immune response to the annual influenza vaccination. Eighty older institutionalised patients suffering from dementia (54 women and 26 men) continuously wore an activity tracker for 8 weeks to assess individual light exposure and rest-activity cycles. We analysed the patients’ immune response from two blood samples taken before and 4 weeks after the annual influenza vaccination. Individual antibody concentrations to three influenza virus strains (H3N2, H1N1, IB) were quantified via hemagglutination inhibition assays. By quantifying individual light exposure profiles (including daylight), we classified the patients into a low and a high light exposure group based on a median illuminance of 392.6 lux. The two light exposure groups did not differ in cognitive impairment severity, age or gender distribution. However, patients in the high light exposure group showed a significantly greater circadian rest-activity amplitude (i.e., more daytime activity and less nighttime activity) along with a significantly greater antibody titer increase to the H3N2 vaccine than patients in the low light exposure group, despite similar pre-vaccination concentrations. Sufficient seroprotective responses to all three influenza virus strains were attained for ≥75% of participants. These data provide preliminary evidence for a potentially enhanced immune response in patients with dementia when they received more daily light. Future studies are needed to determine whether regular daily light exposure may have beneficial effects on the human immune system, either directly or via a stabilising circadian sleep-wake rhythms.

Immune response against DNA- and mRNA vaccines encoding artificial influenza virus immunogens

Constant antigenic drift of circulating influenza viruses leads to inefficiency of seasonal influenza vaccines, thus requiring annual re-design of these vaccines. Therefore, the development of a universal influenza vaccine is of particular relevance. A promising line of research in this area is to design the immunogens consisting of conserved protein fragments from different influenza viral strains. The aim of this work was to assess immunogenicity of DNA vaccines and mRNA vaccines encoding artificial antigens consisting of conserved hemagglutinin stem fragments and conserved M2 protein. We have obtained DNA vaccine constructs encoding artificial immunogens AgH1, AgH3, and AgM2, which contained conserved fragments of the hemagglutinin stalk from the two subtypes of influenza A H1N1 and H3N2, and conserved M2 protein. These DNA vaccines were used as templates for the synthesis of mRNA vaccines. To assess immunogenicity of the obtained constructs, BALB/c mice were immunized with DNA and mRNA vaccines by i/m administration. Assessment of the humoral immune response was carried out by ELISA, using influenza viruses A/Aichi/2/68(H3N2), A/California/07/2009 as antigens and the ULTRIX vaccine containing purified antigens of H1N1 and H3N2 influenza viruses. T cell immune response was assessed using two methods: intracellular cytokine staining (ICS) and ELISpot. ICS was performed to determine CD8+ and CD4+T-lymphocytes producing IFN. ELISpot was carried out using the mouse IFN ELISpot kit (BD). A peptide mixture which included composition of the target antigens, was used for cell stimulation. The results showed that the designed DNA vaccine constructs induce virus-specific humoral and cellular responses in immunized BALB/c mice. Intramuscular administration of the naked mRNA vaccine constructs induced a weak humoral immune response, thus suggesting a need for further work to improve the delivery approaches.

Anti-influenza virus activity of the REV-ERBα agonist SR9009 and related analogues

REV-ERBα is a member of the nuclear receptor superfamily of transcription factors that aids in the regulation of many diseases. However, the prospect of using REV-ERBα for anti-influenza virus treatment remains poorly described, and there is an urgent need to develop effective anti-influenza agents due to the emergence of drug-resistant influenza viruses. In this study, eight SR9009 analogues were designed, synthesized, and evaluated for their biological activities against multiple influenza virus strains (H1N1, H3N2, adamantane- and oseltamivir-resistant H1N1 and influenza B virus), using ribavirin as the positive control. SR9009 and its analogues showed low micromolar or submicromolar EC50 values and exhibited modestly improved antiviral potency compared to that of ribavirin. In particular, compound 5a possessed the most potent inhibitory activity (EC50 = 0.471, 0.644, 1.644, 0.712 and 0.661 μM for A/PR/8/34, A/WSN/33, A/Wisconsin/67/2005, B/Yamagata/16/88 and Hebei/SWL1/2006, respectively). Cotransfection assays showed that all synthesized derivatives efficaciously suppressed transcription driven by the Bmal1 promoter. Mechanistic study results indicated that 5a efficiently inhibited IAV replication and interfered with the ealry stage of influenza virus life cycle. In addition, we found that 5a upregulated the key antiviral interferon-stimulated genes MxA, OAS2 and CH25H. Further in-depth transcriptome analysis revealed a series of upregulated genes that may contribute to the antiviral activities of 5a. These findings may provide an important direction for the development of new host-targeted broad-spectrum antiviral agents.

Low prevalence of influenza A strains with resistance markers in Brazil during 2017-2019 seasons.

The influenza A virus (IAV) is of a major public health concern as it causes annual epidemics and has the potential to cause pandemics. At present, the neuraminidase inhibitors (NAIs) are the most widely used anti-influenza drugs, but, more recently, the drug baloxavir marboxil (BXM), a polymerase inhibitor, has also been licensed in some countries. Mutations in the viral genes that encode the antiviral targets can lead to treatment resistance. Worldwide, a low prevalence of antiviral resistant strains has been reported. Despite that, this situation can change rapidly, and resistant strain surveillance is a priority. Thus, the aim of this was to evaluate Brazilian IAVs antiviral resistance from 2017 to 2019 through the identification of viral mutations associated with reduced inhibition of the drugs and by testing the susceptibility of IAV isolates to oseltamivir (OST), the most widely used NAI drug in the country. Initially, we analyzed 282 influenza A(H1N1)pdm09 and 455 A(H3N2) genetic sequences available on GISAID. The amino acid substitution (AAS) NA:S247N was detected in one A(H1N1)pdm09 strain. We also identified NA:I222V (n = 6) and NA:N329K (n = 1) in A(H3N2) strains. In addition, we performed a molecular screening for NA:H275Y in 437 A(H1N1)pdm09 samples, by pyrosequencing, which revealed a single virus harboring this mutation. Furthermore, the determination of OST IC50 values for 222 A(H1N1)pdm09 and 83 A(H3N2) isolates revealed that all isolates presented a normal susceptibility profile to the drug. Interestingly, we detected one A(H3N2) virus presenting with PA:E119D AAS. Moreover, the majority of the IAV sequences had the M2:S31N adamantanes resistant marker. In conclusion, we show a low prevalence of Brazilian IAV strains with NAI resistance markers, in accordance with what is reported worldwide, indicating that NAIs still remain an option for the treatment of influenza infections in Brazil. However, surveillance of influenza resistance should be strengthened in the country for improving the representativeness of investigated viruses and the robustness of the analysis.

Pro-Inflammatory Cytokines and Interferon-Stimulated Gene Responses Induced by Seasonal Influenza A Virus with Varying Growth Capabilities in Human Lung Epithelial Cell Lines.

In a previous study, we described the diverse growth capabilities of circulating seasonal influenza A viruses (IAVs) with low to high viral copy numbers in vitro. In this study, we analyzed the cause of differences in growth capability by evaluating pro-inflammatory cytokines (TNF-α, IL-6, IFN-β) and antiviral interferon-stimulated genes (ISG-15, IFIM1, and TRIM22). A549 cells (3.0 × 105 cells) were inoculated with circulating seasonal IAV strains and incubated for 6 and 24 h. In cells inoculated for 6 h, IAV production was assessed using IAV-RNA copies in the culture supernatant and cell pellets to evaluate gene expression. At 24 h post-infection, cells were collected for IFN-β and ISG-15 protein expression. A549 cells inoculated with seasonal IAV strains with a high growth capability expressed lower levels of IFN-β and ISGs than strains with low growth capabilities. Moreover, suppression of the JAK/STAT pathway enhanced the viral copies of seasonal IAV strains with a low growth capability. Our results suggest that the expression of ISG-15, IFIM1, and TRIM22 in seasonal IAV-inoculated A549 cells could influence the regulation of viral replication, indicating the existence of strains with high and low growth capability. Our results may contribute to the development of new and effective therapeutic strategies to reduce the risk of severe influenza infections.

Epigallocatechin Gallate Stabilized by Cyclodextrin Inactivates Influenza Virus and Human Coronavirus 229E.

Natural products are attractive antiviral agents because they are environment-friendly and mostly harmless. Epigallocatechin gallate (EGCg), a type of catechin, is a well-known natural antiviral agent that can inhibit various viruses. However, EGCg easily oxidizes and loses its physiological activity. Although this problem can be overcome by combining EGCg with cyclodextrin (CD-EGCg), which makes it stable in water at high concentrations, the antiviral effect of this compound remains unclear. Here, we show that in Madin–Darby canine kidney (MDCK) and MRC-5 cells, CD-EGCg is cytotoxic for 50% of cells at 85.61 and 65.34 ppm, respectively. Furthermore, CD-EGCg mainly shows its antiviral effect during the adsorption step for all four influenza virus strains (median effect concentration (EC50) was 0.93 to 2.78 ppm). Its antiviral effect post-adsorption is less intense, and no inhibitory effect is observed on influenza viruses pre-adsorption. Moreover, human coronavirus 229E (HCoV-229E) was inhibited at the adsorption step in short contact (EC50 = 2.5 ppm) and long contact conditions (EC50 = 0.5 ppm) by mixing CD-EGCg with HCoV-229E. These results suggest that CD-EGCg effectively inhibits various viruses that require an adsorption step, and is an effective tool for preventing infection.

The evolution of humoral immune responses to past and novel influenza virus strains gives evidence for antigenic seniority.

The high genetic and antigenic variability of influenza virus and the repeated exposures of individuals to the virus over time account for the human immune responses toward this pathogen to continuously evolve during the lifespan of an individual. Influenza-specific immune memory to past strains has been shown to affect the immune responses to subsequent influenza strains and in turn to be changed itself through the new virus encounter. However, exactly how and to what extent this happens remains unclear. Here we studied pre-existing immunity against influenza A virus (IAV) by assessing IAV binding (IgG), neutralizing, and neuraminidase-specific antibodies to 5 different IAV strains in 180 subjects from 3 different age cohorts, adolescents, adults, and elderly, over a 5-year time span. In each age cohort, the highest neutralizing antibody titers were seen for a virus strain that circulated early in their life but the highest increase in titer was found for the most recent virus strains. In contrast, the highest IgG titers were seen against recent virus strains but the biggest increase in titer occurred against older strains. Significant increases in neutralizing antibody titers against a newly encountered virus strain were observed in all age cohorts demonstrating that pre-existing immunity did not hamper antibody induction. Our results indicate that the evolution of influenza-specific humoral immunity differs for rather cross-reactive virus-binding antibodies and more strain-specific neutralizing antibodies. Nevertheless, in general, our observations lend support to the antigenic seniority theory according to which the antibody response to influenza is broadened with each virus encounter, with the earliest encountered strain taking in the most senior and thus dominant position.

Vaccination decreases the risk of influenza A virus reassortment but not genetic variation in pigs.

Although vaccination is broadly used in North American swine breeding herds, managing swine influenza is challenging primarily due to the continuous evolution of influenza A virus (IAV) and the ability of the virus to transmit among vaccinated pigs. Studies that have simultaneously assessed the impact of vaccination on the emergence of IAV reassortment and genetic variation in pigs are limited. Here, we directly sequenced 28 bronchoalveolar lavage fluid (BALF) samples collected from vaccinated and unvaccinated pigs co-infected with H1N1 and H3N2 IAV strains, and characterized 202 individual viral plaques recovered from 13 BALF samples. We identified 54 reassortant viruses that were grouped in 17 single and 16 mixed genotypes. Notably, we found that prime-boost vaccinated pigs had less reassortant viruses than nonvaccinated pigs, likely due to a reduction in the number of days pigs were co-infected with both challenge viruses. However, direct sequencing from BALF samples revealed limited impact of vaccination on viral variant frequency, evolutionary rates, and nucleotide diversity in any IAV coding regions. Overall, our results highlight the value of IAV vaccination not only at limiting virus replication in pigs but also at protecting public health by restricting the generation of novel reassortants with zoonotic and/or pandemic potential.

TLR agonists induce sustained IgG to hemagglutinin stem and modulate T cells following newborn vaccination

The newborn immune system is characterized by diminished immune responses that leave infants vulnerable to virus-mediated disease and make vaccination more challenging. Optimal vaccination strategies for influenza A virus (IAV) in newborns should result in robust levels of protective antibodies, including those with broad reactivity to combat the variability in IAV strains across seasons. The stem region of the hemagglutinin (HA) molecule is a target of such antibodies. Using a nonhuman primate model, we investigate the capacity of newborns to generate and maintain antibodies to the conserved stem region following vaccination. We find adjuvanting an inactivated vaccine with the TLR7/8 agonist R848 is effective in promoting sustained HA stem-specific IgG. Unexpectedly, HA stem-specific antibodies were generated with a distinct kinetic pattern compared to the overall response. Administration of R848 was associated with increased influenza-specific T follicular helper cells as well as Tregs with a less suppressive phenotype, suggesting adjuvant impacts multiple cell types that have the potential to contribute to the HA-stem response.

Bioassay-Guided Fractionation of Erythrostemon yucatanensis (Greenm.) Gagnon & GP Lewis Components with Anti-hemagglutinin Binding Activity against Influenza A/H1N1 Virus.

Erythrostemon yucatanensis (Greenm.) Gagnon & GP Lewis is a legume tree native to and widely distributed in southeast Mexico, where its branches are used in traditional medicine. An in vitro evaluation of the antiviral activity of extracts and fractions from the leaves, stem bark and roots against two strains of the AH1N1 influenza virus was performed, leading to the identification of bioactive compounds in this medicinal plant. In a cytopathic effect reduction assay, the fractions from the leaves and stem bark were the active elements at the co-treatment level. These were further fractionated based on their hemagglutination inhibition activity. The analysis of spectroscopy data identified a combination of phytosterols (β-sitosterol, stigmasterol and campesterol) in the stem bark active fraction as the main anti-hemagglutinin binding components, while 5-hydroxy-2(2-hydroxy-3,4,5-trimethoxyphenyl)-7-metoxi-4H(chromen-4-ona), which was isolated from the leaf extracts, showed a weak inhibition of viral hemagglutinin. Time of addition experiments demonstrated that the mixture of sterols had a direct effect on viral particle infectivity at the co-treatment level (IC50 = 3.125 µg/mL). This effect was also observed in the virus plaque formation inhibition assay, where the mixture showed 90% inhibition in the first 20 min of co-treatment at the same concentration. Additionally, it was found using qRT-PCR that the NP copy number was reduced by 92.85% after 60 min of co-treatment. These results are the first report of components with anti-hemagglutinin binding activity in the genus Erythrostemon sp.

The influenza A virus genome packaging network - complex, flexible and yet unsolved.

The genome of influenza A virus (IAV) consists of eight unique viral RNA segments. This genome organization allows genetic reassortment between co-infecting IAV strains, whereby new IAVs with altered genome segment compositions emerge. While it is known that reassortment events can create pandemic IAVs, it remains impossible to anticipate reassortment outcomes with pandemic prospects. Recent research indicates that reassortment is promoted by a viral genome packaging mechanism that delivers the eight genome segments as a supramolecular complex into the virus particle. This finding holds promise of predicting pandemic IAVs by understanding the intermolecular interactions governing this genome packaging mechanism. Here, we critically review the prevailing mechanistic model postulating that IAV genome packaging is orchestrated by a network of intersegmental RNA–RNA interactions. Although we find supporting evidence, including segment-specific packaging signals and experimentally proposed RNA–RNA interaction networks, this mechanistic model remains debatable due to a current shortage of functionally validated intersegmental RNA–RNA interactions. We speculate that identifying such functional intersegmental RNA–RNA contacts might be hampered by limitations of the utilized probing techniques and the inherent complexity of the genome packaging mechanism. Nevertheless, we anticipate that improved probing strategies combined with a mutagenesis-based validation could facilitate their discovery.

Evidence for flock transmission of individual subtypes and strains of avian influenza viruses: A monitoring study of wild birds in Kazakhstan

An active surveillance study of avian influenza viruses (AIVs) in wild birds was carried out in Kazakhstan in 2018–2019. In total, 866 samples were collected from wild birds and analyzed for influenza viruses using molecular and virological tests. Genome segments of Asian, European, and Australian lineages were detected in 25 (4.6%) out of 541 waterfowl samples positive for subtype H3N8, and in two (0.6%) out of 325 H3N8 positive samples from terrestrial birds. No highly pathogenic avian influenza virus (AIV) was detected.The results indicated transmission of closely related strains or identical subtypes of AIVs by a flock-unit of migratory birds or annual cyclical pattern of subtype dominance. The simultaneous circulation of genome segments of the Asian, European and Australian genetic lineages of H3N8 AIVs in wild birds in Kazakhstan indicated the important role of Central Asia as a transmission hub of AI viruses linking the East Asian migratory flyways with European flyways and vice versa.

Membrane Chromatography-Based Downstream Processing for Cell-Culture Produced Influenza Vaccines.

New influenza strains are constantly emerging, causing seasonal epidemics and raising concerns to the risk of a new global pandemic. Since vaccination is an effective method to prevent the spread of the disease and reduce its severity, the development of robust bioprocesses for producing pandemic influenza vaccines is exceptionally important. Herein, a membrane chromatography-based downstream processing platform with a demonstrated industrial application potential was established. Cell culture-derived influenza virus H1N1/A/PR/8/34 was harvested from benchtop bioreactor cultures. For the clarification of the cell culture broth, a depth filtration was selected as an alternative to centrifugation. After inactivation, an anion exchange chromatography membrane was used for viral capture and further processing. Additionally, two pandemic influenza virus strains, the H7N9 subtype of the A/Anhui/1/2013 and H3N2/A/Hong Kong/8/64, were successfully processed through similar downstream process steps establishing optimized process parameters. Overall, 41.3–62.5% viral recovery was achieved, with the removal of 86.3–96.5% host cell DNA and 95.5–99.7% of proteins. The proposed membrane chromatography purification is a scalable and generic method for the processing of different influenza strains and is a promising alternative to the current industrial purification of influenza vaccines based on ultracentrifugation methodologies.

Knockdown of FLT4, Nup98, and Nup205 Cellular Genes Effectively Suppresses the Reproduction of Influenza Virus Strain A/WSN/1933 (H1N1) In vitro.

Influenza is one of the most common infectious diseases, which affects the lower respiratory tract, and can lead to serious complications, including death. It is known that currently available therapeutic agents and vaccines do not provide 100% protection against influenza viruses. The development of drugs based on the RNA interference mechanism in the context of this problem is a promising area. This paper aims to assess the effect of FLT4, Nup98, and Nup205 cellular gene knockdown on the reproduction of the influenza A virus in human lung cell culture. Influenza virus strain A/WSN/1933 (St. Jude's Children's Research Hospital, USA) was used in this work as well as A549 cell culture (human lung adenocarcinoma, ATCC® CCL- 185, USA) and MDCK cell culture (dog kidney cells, Institut Pasteur, France). Small interfering RNAs (siRNAs) (Syntol, Russia) were synthesized for targeting the FLT4, Nup98, and Nup205 genes. Lipofectamin 2000 (Invitrogen, USA) was used for transfection. After 4 hours, the transfected cells were infected with the influenza virus at MOI = 0.1. Virus-containing fluid was collected within three days from the moment of transfection, and the intensity of viral reproduction was assessed by CPE titration and hemagglutination reactions. Viral RNA concentration was determined by RT-PCR. Mann- Whitney U test was used for statistical analysis. In cells treated with siRNA for FLT4, Nup98, and Nup205 genes, there was a significant decrease in the expression of target genes and indicators of viral reproduction (virus titer, hemagglutinating activity, viral RNA concentration) at MOI = 0.1, although the cell survival rate did not decrease significantly. On the first day, the viral titer in cells treated with declared siRNA was lower, on average, by 1 Lg, and on the second and third days, by 2.2-2.3 Lg, compared to cells treated with nonspecific siRNA. During RT-PCR, a significant decrease in the concentration of viral RNA with Nup98.1 and Nup205 siRNA was detected: up to 190 times and 30 times on the first day, 26 and 29 times on the second day, and 6 and 30 times on the third day, respectively. For FLT4.2 siRNA, the number of viral RNA copies has been decreased by 23, 18, and 16 times on the first, second, and third days. Similar results were obtained while determining the hemagglutinating activity of the virus. The hemagglutinating activity decreased mostly (by 16 times) in cells treated with Nup205 and FLT4.2 siRNAs on the third day. In cells treated with FLT4.1, Nup98.1, and Nup98.2 siRNAs, the hemagglutinating activity decreased by 8 times. We identified a number of genes, such as FLT4, Nup98, and Nup205, whose expression can efficiently suppress viral reproduction when their expression is decreased. The original siRNA sequences were also obtained. These results are important for the creation of therapeutic and prophylactic agents, whose action is based on the RNA interference mechanism.

PEtOxylated Interferon-α2a Bioconjugates Addressing H1N1 Influenza A Virus Infection.

Influenza A viruses (IAV), including the pandemic 2009 (pdm09) H1N1 or avian influenza H5N1 virus, may advance into more pathogenic, potentially antiviral drug-resistant strains (including loss of susceptibility against oseltamivir). Such IAV strains fuel the risk of future global outbreaks, to which this study responds by re-engineering Interferon-α2a (IFN-α2a) bioconjugates into influenza therapeutics. Type-I interferons such as IFN-α2a play an essential role in influenza infection and may prevent serious disease courses. We site-specifically conjugated a genetically engineered IFN-α2a mutant to poly(2-ethyl-2-oxazoline)s (PEtOx) of different molecular weights by strain-promoted azide-alkyne cyclo-addition. The promising pharmacokinetic profile of the 25 kDa PEtOx bioconjugate in mice echoed an efficacy in IAV-infected ferrets. One intraperitoneal administration of this bioconjugate, but not the marketed IFN-α2a bioconjugate, changed the disease course similar to oseltamivir, given orally twice every study day. PEtOxylated IFN-α2a bioconjugates may expand our therapeutic arsenal against future influenza pandemics, particularly in light of rising first-line antiviral drug resistance to IAV.

Few Amino Acid Mutations in H6 Influenza A Virus From South American Lineage Increase Viral Replication Efficiency in Poultry.

In chickens, infections due to influenza A virus (IAV) can be mild to severe and lethal. The study of IAV infections in poultry has been mostly limited to strains from the North American and Eurasian lineages, whereas limited information exists on similar studies with strains from the South American lineage (SAm). To better evaluate the risk of introduction of a prototypical SAm IAV strain into poultry, chickens were infected with a wild-type SAm origin strain (WT557/H6N2). The resulting virus progeny was serially passaged in chickens 20 times, and the immunopathological effects of the last passage virus, 20Ch557/H6N2, in chickens were compared to those of the parental strain. A comparison of complete viral genome sequences indicated that the 20Ch557/H6N2 strain contained 13 amino acid differences compared to the wild-type strain. Five of these mutations are in functionally relevant regions of the viral surface glycoproteins hemagglutinin (HA) and neuraminidase (NA). However, despite higher and more prolonged virus shedding in chickens inoculated with the 20Ch557/H6N2 strain compared to those that received the WT557/H6N2 strain, transmission to naïve chickens was not observed for either group. Analyses by flow cytometry of mononuclear cells and lymphocyte subpopulations from the lamina propria and intraepithelial lymphocytic cells (IELs) from the ileum revealed a significant increase in the percentages of CD3+TCRγδ+ IELs in chickens inoculated with the 20Ch557/H6N2 strain compared to those inoculated with the WT557/H6N2 strain.

Live attenuated influenza A virus vaccines with modified NS1 proteins for veterinary use.

Influenza A viruses (IAV) spread rapidly and can infect a broad range of avian or mammalian species, having a tremendous impact in human and animal health and the global economy. IAV have evolved to develop efficient mechanisms to counteract innate immune responses, the first host mechanism that restricts IAV infection and replication. One key player in this fight against host-induced innate immune responses is the IAV non-structural 1 (NS1) protein that modulates antiviral responses and virus pathogenicity during infection. In the last decades, the implementation of reverse genetics approaches has allowed to modify the viral genome to design recombinant IAV, providing researchers a powerful platform to develop effective vaccine strategies. Among them, different levels of truncation or deletion of the NS1 protein of multiple IAV strains has resulted in attenuated viruses able to induce robust innate and adaptive immune responses, and high levels of protection against wild-type (WT) forms of IAV in multiple animal species and humans. Moreover, this strategy allows the development of novel assays to distinguish between vaccinated and/or infected animals, also known as Differentiating Infected from Vaccinated Animals (DIVA) strategy. In this review, we briefly discuss the potential of NS1 deficient or truncated IAV as safe, immunogenic and protective live-attenuated influenza vaccines (LAIV) to prevent disease caused by this important animal and human pathogen.

Debulking different Corona (SARS-CoV-2 delta, omicron, OC43) and Influenza (H1N1, H3N2) virus strains by plant viral trap proteins in chewing gums to decrease infection and transmission

Because oral transmission of SARS-CoV-2 is 3–5 orders of magnitude higher than nasal transmission, we investigated debulking of oral viruses using viral trap proteins (CTB-ACE2, FRIL) expressed in plant cells, delivered through the chewing gum. In omicron nasopharyngeal (NP) samples, the microbubble count (based on N-antigen) was significantly reduced by 20 μg of FRIL (p < 0.0001) and 0.925 μg of CTB-ACE2 (p = 0.0001). Among 20 delta or omicron NP samples, 17 had virus load reduced below the detection level of spike protein in the RAPID assay, after incubation with the CTB-ACE2 gum powder. A dose-dependent 50% plaque reduction with 50–100 ng FRIL or 600–800 μg FRIL gum against Influenza strains H1N1, H3N2, and Coronavirus HCoV-OC43 was observed with both purified FRIL, lablab bean powder or gum. In electron micrographs, large/densely packed clumps of overlapping influenza particles and FRIL protein were observed. Chewing simulator studies revealed that CTB-ACE2 release was time/dose-dependent and release was linear up to 20 min chewing. Phase I/II placebo-controlled, double-blinded clinical trial (IND 154897) is in progress to evaluate viral load in saliva before or after chewing CTB-ACE2/placebo gum. Collectively, this study advances the concept of chewing gum to deliver proteins to debulk oral viruses and decrease infection/transmission.

MicroRNA let-7 Suppresses Influenza A Virus Infection by Targeting RPS16 and Enhancing Type I Interferon Response.

Given the frequent emergence of drug-resistant influenza virus strains and new highly pathogenic influenza virus strains, there is an urgent need to identify new antiviral drugs and targets. We found that influenza A virus (IAV) infection caused a significant decrease of microRNA let-7 expression in host cells; that overexpression of let-7 increased interferon expression and effectively inhibit IAV infection; and that let-7 targets the 3’-untranslated region (UTR) of the ribosomal protein 16 (RPS16) gene, decreasing its expression. Knocking down the expression of RPS16 increased the expression of type I interferon and inhibited viral replication. The present study uncovered the regulatory effect of let-7b and let-7f on influenza A infection, which is a potential biomarker of IAV infection. In addition, let-7 may be a promising therapeutic agent against influenza A.

Parasite-induced shifts in host movement may explain the transient coexistence of high- and low-pathogenic disease strains.

Many parasites induce decreased host movement, known as lethargy, which can impact disease spread and the evolution of virulence. Mathematical models have investigated virulence evolution when parasites cause host death, but disease-induced decreased host movement has received relatively less attention. Here, we consider a model where, due to the within-host parasite replication rate, an infected host can become lethargic and shift from a moving to a resting state, where it can die. We find that when the lethargy and disease-induced mortality costs to the parasites are not high, then evolutionary bistability can arise, and either moderate or high virulence can evolve depending on the initial virulence and the magnitude of mutation. These results suggest, firstly, the coexistence of strains with different virulence, which may explain the transient coexistence of low- and high-pathogenic strains of avian influenza viruses, and secondly, that medical interventions to treat the symptoms of lethargy or prevent disease-induced host deaths can result in a large jump in virulence and the rapid evolution of high virulence. In complement to existing results that show bistability when hosts are heterogeneous at the population level, we show that evolutionary bistability may arise due to transmission heterogeneity at the individual host level.