ETIDIOH - NEW

Abstract On November 2, 2018, a person-to-person transmission outbreak of Andes virus (Orthohantavirus andesense) began in the small town of Epuyén, Argentina . The strain demonstrated a high capacity for sustained transmission among the human population requiring the implementation of quarantine measures , rigorous contact tracing , isolation of close contacts, and active clinical monitoring to prevent further spread. In this study, we report the isolation of this strain, which we name the ARG-Epuyén strain , directly from a clinical sample after just three passages in cell culture. Complete sequencing revealed only a single amino acid change post-isolation , suggesting that this strain can be considered a non-adapted wild-type Andes virus , marking a critical step toward the development of medical countermeasures against this emerging pathogen. The pathogenicity and transmissibility potential of ARG-Epuyén were evaluated in hamsters , the only animal model for Hantavirus Pulmonary Sy...

ABSTRACT A cocktail of human monoclonal antibodies 1C3 and 1C11 previously protected macaques from a lethal exposure to either Ebola virus (EBOV) or Sudan virus (SUDV). 1C3 is of particular interest because its paratope strongly binds with unique stoichiometry to the glycoprotein head of several orthoebolaviruses , resulting in neutralization of EBOV and SUDV . Therefore, we evaluated the protective activity of 1C3 as a standalone therapeutic in macaques exposed to either EBOV or SUDV. Two doses of 1C3 monotherapy, administered 4 and 7 days post-exposure, did not protect SUDV-exposed macaques and partially protected EBOV-exposed macaques . Notably, in a macaque that succumbed to EBOV infection, we identified two mutually exclusive escape mutations that emerged immediately after the first dose and resulted in two amino acid changes at the 1C3 binding site . We also detected a subconsensus treatment-emergent mutation likely affecting the 1C3 binding site in all three deceased SUDV-expose...

Abstract Since 2021, the novel H10N3 has caused four cases of human infection in China, the most recent of which occurred in December 2024 , posing a potential threat to public health. Our previous studies indicated that several avian H10N3 strains are highly pathogenic in mice and can be transmitted between mammals via respiratory droplets without prior adaptation. By analyzing the genome sequence , we found that these H10N3 viruses carry the PB2-E627V mutation , which is becoming increasingly common in several subtypes of avian influenza viruses (AIV); however, its mechanism in mammalian adaptation remains unclear. Using a reverse genetics system , we investigated the role of PB2-E627V in the adaptation of H10N3 to mammals and poultry. Our findings demonstrate that the PB2-E627V mutation is critical for the high pathogenicity of novel H10N3 in mice and its ability to be transmitted through the air among mammals . Additionally, we found that the role of PB2-627 V in promoting AIV adap...

Abstract Seasonal influenza viruses continue to pose a significant threat, causing substantial morbidity and mortality in the US and worldwide despite the availability of vaccines and antivirals. These challenges may be addressed by improving vaccine immunogenicity through the inclusion of adjuvants that enhance immune responses against key antigens including influenza hemagglutinin (HA). BECC (Bacterial Enzymatic Combinatorial Chemistry) adjuvants are novel Toll-like Receptor 4 (TLR4) ligands created by modifying enzymes from lipid A synthesis pathways in Gram-negative bacteria. This study compares the ability of the biological and synthetic versions of these adjuvants to enhance the efficacy of recombinant HA (rHA) antigens in mouse influenza virus challenge . Mice immunized with rHA adjuvanted with BECCs stimulate the humoral and cell-mediated arms of the immune system without exhibiting cytotoxicity/pyrogenicity. A robust HA-specific immunoglobulin subtype, especially IgG2a, respon...

Abstract The highly pathogenic avian influenza virus (HPAIV) H5N1 clade 2.3.4.4b has rapidly disseminated globally , with mammalian infections reported in multiple species. Recent evidence of mammal-to-mammal transmission has heightened concerns about the virus’s potential adaptation to mammals . The polymerase basic 2 (PB2) protein E627K mutation appears to be of key importance for mammalian adaptation. We isolated an HPAI H5N1 clade 2.3.4.4b virus from wild birds in Korea with 96% E and 4% K at amino acid position 627 of PB2 . To investigate the genomic characteristics of this clade regarding mammalian adaptation, we studied the replication and transmission of the H5N1 virus in mice. Two experiments with different challenge-to-contact ratios were conducted to assess transmission dynamics and mutation development . In experiment 1, a 4:1 challenge-to-contact ratio resulted in 100% transmission among direct-contact mice , with all mice succumbing to the infection. In experiment 2, a 1:...

Abstract Since multiple and unpredicted influenza viruses cause seasonal epidemics and even high-risk pandemics , developing a universal influenza vaccine is essential to provide broad protection against various influenza subtypes. Combined with the mRNA lipid nanoparticle-encapsulated (mRNA-LNP) vaccine platform and chimeric immunogen strategy , we developed a novel cocktail mRNA vaccine encoding chimeric HAs (cH5/1-BV, cH7/3) and intact M2 (termed Fluaxe), which confers broad protection against major circulating IAVs and IBVs , as well as highly pathogenic avian influenza . Two-dose intramuscular immunization of Fluaxe in mice elicited cross-reactive neutralizing antibodies , T cell responses, and long-lived immunity, resulting in robust protection against multiple lethal influenza virus infections and severe acute lung injuries . In particular, intramuscular administration stimulated systemic immunity together with a prominent lung tropism of memory cells . Moreover, Fluaxe immuniza...

Significance In 2021, antimicrobial-resistant bacteria were responsible for 1.14 million deaths and associated with 4.71 million deaths globally. Patients who experience sepsis often face a higher risk of reinfections and hospital readmissions . To combat this crisis, bacteriophages —viruses that infect and kill bacteria—are regaining interest as a potential solution. Here, we show that mice infected with extraintestinal pathogenic Escherichia coli and treated with phage HP3 not only recover from the initial infection but also gain protection against a secondary challenge with the same bacterial strain. The protective effect is dependent on the bacteriolytic action of the phage. These findings shift phages from being solely therapeutic antimicrobials to dual-action immunotherapeutics capable of both clearing and preventing bacterial infections. Abstract Bacteriophages, or phages, are viruses that target and infect bacteria. Due to a worldwide rise in antimicrobial resistance (AMR), pha...

ABSTRACT Long-distance migratory ducks play a critical role in the maintenance and dissemination of A(H5N1) viruses . Comparative pathogenicity studies were conducted on blue-winged teal (BWTE; Anas discors) using three distinct genotypes of A(H5N1) clade 2.3.4.4b viruses (A1, B1.3, and B4.1) isolated from wild ducks in Canada . Twenty-four hours post-intranasal infection of BWTE, contact turkeys and chickens were introduced into each of the groups to evaluate viral transmission. The levels of viral shedding in BWTE increased from 3 to 7 days post-infection (dpi) and continued at lower levels until 14 dpi. The A1 genotype virus (MALL/NS/22) was found to be the least pathogenic to BWTE compared to the reassortant genotypes, B4.1 (RBME/BC/22) and B1.3 (BWTE/MB/22). The B1.3 genotype was the most virulent to BWTE and caused 66.7% mortality compared to 12.5% mortality caused by the B4.1 genotype. The extent of transmission from infected BWTE to contact turkeys and chickens showed variation...

Abstract Since the first emergence of highly pathogenic avian influenza (HPAI) H5N1 viruses in dairy cattle , the virus has continued to spread, reaching at least 17 states and at least 950 dairy herds in the United States. Subsequently, spillovers of the virus from dairy cattle to humans have been reported. Pigs are an important reservoir in influenza ecology because they serve as a mixing vessel in which novel reassortant viruses with pandemic potential can be generated. Here, we show that oro-respiratory infection of pigs resulted in productive replication of a bovine-derived HPAI H5N1 B3.13 virus . Infectious virus was mainly identified in the lower respiratory tract of principal infected pigs, and sero-conversion was observed in most of the principal pigs at later time points, suggesting limited replication of the bovine-derived HPAI H5N1 B3.13 virus in pigs. In one animal, we detected the emergence of a mutation in hemagglutinin (HA) previously associated with increased affinity ...

ABSTRACT Influenza infection and vaccination impart strain-specific immunity that protects against neither seasonal antigenic variants nor the next pandemic . However, antibodies directed to conserved sites can confer broad protection. Here, we identify and characterize a class of human antibodies that engage a previously undescribed, conserved epitope on the influenza hemagglutinin (HA) protein. Prototype antibody S8V1-157 binds at the normally occluded interface between the HA head and stem. Antibodies to this HA head–stem interface epitope are non-neutralizing in vitro but protect against lethal influenza infection in mice. These antibodies bind to most influenza A subtypes and seasonal human variants, and are present at low frequencies in the memory B cell populations of multiple human donors. Vaccines designed to elicit these antibodies might contribute to “universal” influenza immunity. IMPORTANCE Antibodies to the influenza virus hemagglutinin (HA) protein confer the strongest p...

Abstract Avian influenza viruses continue to challenge poultry and human health ; therefore, careful surveillance and evaluation of emerging viruses are important for animal disease control and human influenza pandemic preparedness . In this study, we detected a series of H3N3 subtype avian influenza viruses in chickens , pigeons, and ducks during our routine surveillance and diagnosis between September 2022 and May 2023. We performed extensive analyses to fully understand the origins of these viruses and their risk to animals and humans. We found that the viruses were complex reassortants ; the viruses from chickens and pigeons carry genes mainly derived from H3N8 viruses and H10N3 viruses , whereas the two duck viruses were reassortants of duck and wild bird viruses. The chicken and pigeon , but not duck, viruses replicated in multiple organs of chickens and were shed for up to 13 days, but none caused disease or death. Six of the viruses tested all bound to both avian- and human-typ...

Abstract The interspecies transmission of avian influenza viruses remains a significant public health concern. H6 viruses have gained attention following the first human infection by a chicken-origin H6N1 virus (A/Taiwan/02/2013, Hu/13), highlighting their zoonotic potential . To understand the evolutionary trajectory and mammalian adaptation of this Taiwan lineage , we compared two avian isolates (A/Chicken/Taiwan/CF19/2009, Ck/09; A/Chicken/Taiwan/2267/2012, Ck/12) and Hu/13 in vitro and in vivo. Hu/13 exhibited enhanced replication in MDCK cells , producing larger plaques and higher viral titers than Ck/09 and Ck/12. In BALB/c mice , Hu/13 demonstrated the highest pathogenicity and mortality , followed by Ck/12, while Ck/09 induced minimal morbidity. Hu/13 and Ck/12 replicated efficiently in respiratory tissues , eliciting robust cytokine responses and severe pulmonary lesions . In ferrets , Hu/13 showed relatively efficient transmission , infecting all direct physical-contact and t...

Abstract Nipah virus, a zoonotic pathogen, can cause debilitating disease and death in humans. Currently, countermeasures are limited , with several in various stages of testing but none yet FDA-approved for human use. Evaluation of countermeasure candidates requires safety testing in humans, as well as efficacy testing against lethal challenge in animal models . Herein, we describe the characterization and comparison of the intraperitoneal and intranasal Syrian golden hamster models for Nipah virus strains Malaysia and Bangladesh . Overall, the intraperitoneal route of exposure resulted in a more consistent lethal outcome, regardless of virus strain. Therefore, the IP model was subsequently used to evaluate the use of Favipiravir as a potential positive control for future studies investigating NiV countermeasures. In contrast to prior reported results regarding Favipiravir in Nipah virus-infected hamsters, Favipiravir was only fifty percent effective at preventing death following leth...

ABSTRACT Sporadic human infections of avian influenza virus (AIV) raise significant public health concerns . A critical factor limiting the transmission of AIVs is the shift in receptor-binding preference from Siaα2,3 to Siaα2,6. To reveal the adaptive selection dynamics during the host adaptation process of AIVs, this study generated a viral library with random mutations in the HA gene of the H9N2 strain . Upon passaging the viral library in chickens and mice , the predominantly selected variants exhibited a preference for Siaα2,3 receptors . Notably, the wild-type strain remained dominant in both inoculated and direct-contact chickens, while variants with the ΔL226/R229I substitutions were preferentially selected in mice. Ferrets have a predominance of Siaα2,6 in their respiratory tract. As expected, the variant harboring the N289D mutation, which prefers Siaα2,6 binding, was enriched during in vivo passaging in ferrets . The mice-adapted variant with the ΔL226/R229I mutations causes...

Abstract The GreVac vaccine technology was created as a fast and flexible plug-and-play vaccine platform based on a 4th generation architecture of fully deleted (fd) helper virus independent (hi) adenoviral (Ad) vectors. For the initial proof-of-principle studies , we at Greffex had engineered an avian influenza vaccine , which delivered a transgene expression cassette for an avian influenza virus H5 hemagglutinin and N1 neuraminidase genes in a capsid of the common human Ad serotype 5 (Ad5). This vaccine proved highly immunogenic and protective in mice . These studies revealed that intramuscular (i.m.) delivery proved more efficient than subcutaneous (s.c.) or intranasal (i.n.) routes. In the human population, pre-exposure to the Ad5 virus is common. To minimize interference by pre-existing anti-Ad5 immunities, we created a new GreVac-based avian influenza vaccine, in which the fd Ad genome was packaged into a capsid of the rare human Ad serotype 6 (Ad6). We now report that at very lo...

Abstract The Sudan virus (SUDV) outbreaks in Uganda in 2022 and 2025 created public health concerns in-country and the entire East African region. There are currently no licensed countermeasures against SUDV . We developed a SUDV vaccine candidate based on a nanocarrier (LIONTM) complexed with an alphavirus-based replicon RNA . Here, we compare the protective efficacy of the LION-SUDV vaccine either encoding the SUDV glycoprotein (GP) alone or in combination with the Ebola virus (EBOV) GP (LION-Combination). A LION-EBOV vaccine which is protective against EBOV was also included to determine the potential for cross-protection against SUDV infection . Single-dose vaccinations were conducted three weeks before challenge with a lethal dose of guinea pig-adapted SUDV using a female guinea pig disease model. We demonstrate 100% survival and protection with the LION-SUDV and the LION-Combination vaccines, while the LION-EBOV vaccine achieved 50% protection. Antigen-specific humoral responses ...

Highlights •  Reconstituted human airway epithelia (HAE) are more effective than cell lines or mouse models for generating and predicting resistance-conferring mutations. •  The resistance barrier of oseltamivir is superior to baloxavir or HA targeting compounds in HAE or mouse model. •  HA-targeting therapeutics quickly led to resistant HA mutations without compromising viral fitness. •  A baloxavir-resistant virus with PA mutations E23G and C241Y was isolated in HAE. •  Combined therapy using clinical antiviral compounsd and HA-targeting compounds did not prevent the emergence of HA mutations. Abstract Influenza viruses pose a significant threat due to annual epidemics and pandemic potential . Resistance to current antivirals underscores the need for new drugs and strategies to prevent its emergence. We previously developed two novel HA-targeting compounds (CD-6’SLN and CD-SA) with demonstrated efficacy against influenza A and B strains . Here, we compared the...

Abstract The global spread, frequent antigenic changes, and pandemic potential of clade 2.3.4.4b highly pathogenic avian influenza H5N1 underscore the urgent need for robust cross-protective vaccines . Here, we developed a clade 2.3.4.4b H5N1 whole inactivated virus (WIV) vaccine strain with improved structural stability, productivity, and safety. By analyzing the evolutionary trends of clade 2.3.4.4b H5N1 viruses, we identified a key mutation (R90K) that increases heat stability while preserving antigenicity. Additionally, the PB2 gene of PR8 was replaced with a prototypical avian PB2 gene to increase replication efficiency in embryonated chicken eggs and reduce replication efficiency in mammalian cells, thereby improving productivity and biosafety. We found that our optimized clade 2.3.4.4b H5N1 vaccine strain (22W_KY), inactivated with binary ethylenimine (BEI), had superior antigen internalization into respiratory epithelial cells compared to those inactivated with formaldehyde or ...

Abstract Influenza A(H5N1) viruses have been detected in US dairy cow herds since 2024 . We assessed the pathogenesis, transmission, and airborne release of A/Michigan/90/2024, an H5N1 isolate from a dairy farm worker in Michigan , in the ferret model. Results show this virus caused airborne transmission with moderate pathogenicity , including limited extrapulmonary spread , without lethality. Highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b viruses have displayed unprecedented global spread among wild birds leading to numerous spillover infections in mammalian species. Of note, outbreaks in dairy cattle and gallinaceous birds have resulted in human infections in the United States during 2024–2025 (1). Increased frequency of H5N1 viruses crossing species barriers has caused concern that the avian influenza viruses are adapting to mammals . A critical component of influenza pandemic preparedness is early identification of emerging novel influenza viruses that cause disease and t...

Abstract The ongoing panzootic of H5N1 high pathogenicity avian influenza virus (HPAIV) has caused the deaths of over half a billion wild birds and poultry , and has led to spillover events in both wild and domestic mammals , alongside sporadic human infections . A key driver of this panzootic is the apparent high viral fitness across diverse avian species, which facilitates an increased interface between wild and domestic species. Columbiformes (pigeons and doves) are commonly found on poultry premises and are highly connected to humans in urban settlements, yet relatively little is known about their potential role in contemporary HPAIV disease ecology. Here we investigated the epidemiological role of pigeons (Columba livia) by determining their susceptibility using decreasing doses of clade 2.3.4.4b H5N1 HPAIV (genotype AB). We investigated infection outcomes and transmission potential between pigeons and to chickens for each dose. Following direct inoculation, pigeons did not develo...