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Showing posts with the label animal models

Maternal #Influenza A Virus #Infection Induces Antiviral and Immune Dysregulation in the #Placenta and #Fetus Without Vertical Transmission

  Abstract Influenza A virus (IAV) infection during pregnancy is associated with stillbirth and preterm birth , possibly by disrupting placental and fetal immunity . To investigate this, pregnant pigtail macaques were inoculated with IAV [A/California/07/2009 (H1N1)] and examined at necropsy 5 days post-infection (N=11) versus uninfected controls (N=16). Stillbirth occurred in 18% of infected pregnancies but not in controls. While vertical transmission was not observed, low levels of viral RNA were detected in two placentas . Maternal IAV infection was associated with increased placental IL-1β and IFN-β levels and an upregulated type I interferon and integrated stress transcriptional response. Fetuses exposed to IAV had greater frequencies of innate immune cells in lymph nodes and CD4+ T cells in lungs . These results suggest that placental and fetal immune environments undergo immune activation independent of the severity of maternal lung infection. Influenza vaccination during pr...

Protective efficacy of the UniFluVec #influenza #vaccine vector against the highly pathogenic influenza A/Indonesia/5/2005 #H5N1 strain in #ferrets

  Highlights •  UniFluVec, an H1N1pdm vaccine candidate , includes NS1 and NEP modifications to boost attenuation and immunity. •  UniFluVec protects ferrets from H5N1 , enhancing clearance, limiting lung damage, and ensuring 100 % survival after one dose. •  Replication-deficient UniFluVec shows cross-protection , supporting its potential as a pre-pandemic intranasal vaccine. Abstract Background The emergence of new influenza strains with unpredictable antigenic properties poses a significant vaccination challenge. The increasing incidence of human H5 infections underscores the urgent need for effective pre-pandemic vaccines. Methods The UniFluVec and UniFluVec-wtNS1 viruses were designed as H1N1pdm vaccine candidates . Both viruses contained a heterologous A/Singapore/1/57-like (H2N2) NEP gene , which served as an attenuation factor . UniFluVec additionally carried a truncated to 124 amino acids NS1 gene , and an insertion of conserved influenza sequences. UniFluVe...

Repeated #oral #exposure to #H5N1 #influenza virus in pasteurized #milk does not cause adverse responses to subsequent influenza #infection

  Abstract In March 2024, a highly pathogenic avian influenza H5N1 (HPAI) clade 2.3.4.4b virus was identified in US dairy cows , with spillover to cats, poultry, and humans . Up to 30% of commercial pasteurized milk tested contained viral genome copies . The impact of residual viral remnants on host immunity is unknown. Orally ingested proteins can stimulate gut-associated lymphoid tissues , potentially inducing tolerance and altering responses to later infection. We found that milk pasteurization fully inactivated pandemic H1N1 and bovine H5N1 influenza viruses yet preserved hemagglutinin (HA) protein integrity. In mice , repeated oral exposure to inactivated virus did not alter mortality after H5N1 virus challenge. Preliminary data showed that naïve mice exposed to improperly pasteurized milk containing live H5N1 virus developed lethal infection , whereas prior H1N1 infection conferred protection . Mice with preexisting H1N1 immunity remained protected when challenged with bovine...

Dual-Route #H5N1 #Vaccination Induces Systemic and #Mucosal #Immunity in Murine and Bovine Models

  Abstract Since its discovery in U.S. dairy cattle in early 2024, the highly pathogenic H5N1 avian influenza (clade 2.3.4.4b) has spread widely among herds, causing major economic losses. This zoonotic event emphasizes the urgent need for H5 vaccines that elicit strong, durable, cross-reactive immune responses in cattle , especially young calves. To address this, we immunized mice and cattle with a centralized consensus H5 vaccine, designed to localize to the central node of the human H5 phylogenetic tree . The vaccine was delivered using serotype-switched adenoviral vectors in a prime:boost regimen , combined with intramuscular and intranasal coadministration to target systemic and mucosal immunity and elicit strong humoral and cellular immune responses. This approach strategically integrates multiple innovative features: centralized consensus immunogens, mucosal targeting, and vector serotype switching that are aimed at maximizing immune protection against H5N1 viruses . Our res...

Non-neutralizing #antibodies to #influenza A #matrix-protein-2-ectodomain are broadly effective #therapeutics and resistant to viral escape mutations

  Abstract Influenza A viruses remain a global health threat, yet no universal antibody therapy exists . Clinical programs have centered on neutralizing mAbs , only to be thwarted by strain specificity and rapid viral escape . We instead engineered three non-neutralizing IgG2a mAbs that target distinct, overlapping epitopes within the conserved N terminus of the M2 ectodomain (M2e). Combined at low dose, this “triple M2e-mAb” confers robust prophylactic and therapeutic protection in mice challenged with diverse human and zoonotic IAV strains, including highly pathogenic variants. Therapeutic efficacy depends on Fc-mediated effector activity via FcγRI, FcγRIII, and FcγRIV, rather than in vitro neutralization. Serial passaging in triple M2e-mAb–treated immunocompetent and immunodeficient hosts failed to generate viral escape mutants. Our findings redefine the influenza-specific antibody therapeutic design and support Fc-optimized, non-neutralizing M2e-mAbs as a broadly effective, mut...

Identification of #clinical and #virological correlates associated with #influenza A candidate #vaccine virus (#CVV) attenuation in a #ferret model

  ABSTRACT Influenza A viruses continuously circulate among avian and swine species, posing a persistent threat to public health . The development of influenza candidate vaccine viruses (CVVs) plays a pivotal role in the global strategy for influenza pandemic preparedness . Safety-testing of CVVs for attenuation in ferrets represents a critical step that takes place prior to making these viruses available to vaccine manufacturers . Development of pathogenicity standards is needed to establish acceptable thresholds of disease so that CVV safety can be assessed without the need for comparison to the parental virus. To assess the capacity of diverse CVVs to cause pathogenesis in mammalian hosts , clinical and virological parameters were compiled from CVV assessments in ferrets conducted using consistent methods over approximately 20 years to identify disease parameters most reflective of attenuation compared to wild-type strains. These analyses revealed an overall reduction in ferret ...

Effect of Seasonal #Influenza #Vaccines on Avian Influenza #H5N1 Clade 2.3.4.4b Virus #Infection in #Ferrets

  Abstract Highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b viruses have infected >1,000 herds of dairy cattle and hundreds of poultry flocks in the United States since the beginning of 2024. Seventy human cases have been reported during that period, mainly through occupational exposure . Although prior influenza A(H1N1)pdm09 virus infection has been shown to confer protection against influenza A(H5N1) clade 2.3.4.4b virus infection in the ferret model, it remains unclear if influenza vaccines , known to elicit a less potent and narrower cross-reactive immune response, can achieve a similar effect. In this article, we demonstrate that immunization with commercially available human seasonal influenza vaccines also confers partial protection against disease caused by H5N1 clade 2.3.4.4b virus in ferrets , which is partially associated with the presence of cross-reactive antibodies targeting H5N1 virus antigens. Source: US Centers for Disease Control and Prevention,  h...

Effective #treatment of advanced #Oropouche virus, Rift Valley fever virus, and Dabie #bandavirus #infections with 4'-fluorouridine

  ABSTRACT Oropouche virus (OROV), Rift Valley fever virus (RVFV), and Dabie bandavirus (DBV) are significant re-emerging and emerging human pathogens with major public health implications. Notably, the ongoing OROV disease epidemic spanning South America, Central America, and the Caribbean now exceeds 11,000 cases, including several fatalities and reports of neurological disease and congenital abnormalities associated with infection. Rift Valley fever outbreaks continue to plague sub-Saharan Africa , and DBV, the etiologic agent of severe fever with thrombocytopenia syndrome (SFTS), is expanding its reach throughout several Asian countries . No vaccines or approved therapies are available to prevent or treat these viral infections. Here, we report on the antiviral activity and protective efficacy of the ribonucleoside analog , 4′-fluorouridine (4′-FlU), against OROV, RVFV, and DBV in cell culture and murine models of infection and disease. In cell culture, the potency of 4′-FlU wa...

#Ebola virus’ hidden #target: virus #transmission to and infection of #skin

  ABSTRACT Ebola virus (EBOV), the causative agent of Ebola virus disease, remains one of the World Health Organization’s top 10 threats to global health . Infectious EBOV virions can be found on the surface of skin late in infection and may be transmitted to others through skin-to-skin contact . We investigate in vivo EBOV tropism and the kinetics of virus movement to and from the skin. Increasing viral loads were detected over time in the skin of EBOV-infected non-human primates and mice , with antigen detected in dermal stromal and immune cells . Epidermal cells within and surrounding hair follicles also harbored viral antigen , suggesting a novel mechanism of virus egress to the epidermal surface. During late infection, proinflammatory responses were elevated in infected visceral organs but minimal in the skin despite significant viral loads. We observed similar viral trafficking and cell tropism in the skin of mice intraperitoneally infected with a low containment EBOV model v...

Spatial #variation of infectious virus #load in aggregated day 3 post-inoculation respiratory tract #tissues from #influenza A virus-infected #ferrets

  ABSTRACT The ferret model is widely used to study influenza A viruses (IAVs) isolated from multiple avian and mammalian species , as IAVs typically replicate in the respiratory tract of ferrets without the need for prior host adaptation . During standard IAV risk assessments , tissues are routinely collected from ferrets at a fixed time point post-inoculation to assess the capacity for systemic spread. Here, we describe a data set of virus titers in tissues collected from both respiratory tract and extrapulmonary sites 3 days post-inoculation from over 300 ferrets inoculated with more than 100 unique IAVs (inclusive of H1, H2, H3, H5, H7 , and H9 IAV subtypes, both mammalian and zoonotic origin ). All experiments were conducted by a single research group under a uniform experimental protocol , making it the largest well-controlled publicly available data set to date of discrete tissue titers reported on a per-ferret level. Analysis of these tissues revealed spatial variation in i...

#H5N1 #influenza VLPs based on BEVS induce robust functional #antibodies and immune responses

  Highlights •  The H5N1 influenza virus-like particle vaccines are prepared through baculovirus expression vector system. • In vitro assessments have confirmed that this VLP vaccine has the correct conformation and functional activity. • This VLP vaccine induces robust humoral and cellular immune responses in mice , and provides complete protection against infection with the matched strain. Abstract Avian influenza virus infections pose a potential pandemic threat . The currently licensed vaccines have inherent limitations, emphasizing the urgent need for improved influenza vaccines. Here, we developed a novel hemagglutinin (HA) virus-like particle (VLP) vaccine candidate through the baculovirus expression vector system (BEVS). The engineered VLPs incorporate HA from H5N1 and matrix 1 (M1) protein from H1N1 . Comprehensive characterization revealed that purified HA VLPs exhibited morphological fidelity to native influenza virions while maintaining key viral biological propert...

#Molnupiravir inhibits #Bourbon virus #infection and disease-associated #pathology in mice

  ABSTRACT Bourbon virus (BRBV) is an emerging tick-borne virus that can cause severe and fatal disease in humans . BRBV is vectored via the Amblyomma americanum tick , which is widely distributed throughout the central, eastern, and southern United States . Serosurveillance studies in Missouri and North Carolina identified BRBV-neutralizing antibodies in approximately 0.6% of tested individuals . To date, no specific antiviral therapy exists. As part of an initial screen, several nucleoside analogs were tested for their ability to inhibit BRBV replication in cell culture. Among the compounds assessed, molnupiravir , an antiviral drug with oral availability and broad spectrum antiviral activity against RNA viruses, showed antiviral activity against BRBV production in vitro. In vivo, pre-exposure administration of molnupiravir protected susceptible type I interferon receptor knockout (Ifnar1-/-) mice against lethal BRBV infection. The protection by molnupiravir was associated with l...

#Pathogenicity of #SARS-CoV-2 #Omicron #Subvariants #JN.1, #KP.2, and #EG.5.1 in K18-hACE2 Transgenic #Mice

  Abstract The emergence of the SARS-CoV-2 JN.1 lineage in late 2023 marked a major shift in viral evolution . By January 2024, it had displaced XBB variants to become the dominant strain worldwide. JN.1 and its descendants are antigenically distinct from earlier Omicron subvariants , with approximately 30 additional spike mutations compared to XBB-derived viruses. The combination of these features alongside growing evidence of considerable immune evasion prompted the FDA to recommend that vaccine formulations be updated to target JN.1 rather than XBB.1.5. The continued dominance of JN.1-derived variants necessitates the characterization of viral infection in established animal models to inform vaccine efficacy and elucidate host–pathogen interactions driving disease outcomes. In this study, transgenic mice expressing human ACE2 were infected with SARS-CoV-2 subvariants JN.1, KP.2, and EG.5.1 to compare the pathogenicity of JN.1-lineage and XBB-lineage SARS-CoV-2 viruses. Infection...

An emerging #PB2-627 #polymorphism increases the #zoonotic #risk of avian #influenza virus by overcoming ANP32 host restriction in mammalian and avian hosts

  ABSTRACT Alterations in the PB2-627 domain of avian influenza virus (AIV) can potentially increase the risk of cross-host species infections in humans and mammals . Recently, there has been a rise in human cases of AIV infections without the presence of the known mammalian determinant PB2-E627K . Here, we identified a variant, PB2-627V , which has evolved in poultry and has contributed to the increase in human AIV infections . By screening global PB2 sequences , we discovered a new independent cluster of PB2-627V that emerged in the 2010s , prevalent in avian, mammalian, and human AIV isolates , including those of H9N2, H7N9, H3N8, 2.3.4.4b H5N1 , and other subtypes. We functionally assessed its host adaptation , fitness , and transmissibility across three subtypes of AIVs (H9N2, H7N9, and H3N8) in different host models . PB2-627V combines the viral properties of avian-like PB2-627E and human-like PB2-627K , facilitating AIVs to efficiently infect and replicate in chickens and mi...

Single-Cell #Network #Analysis Identifies CLEC4E as a Key Mediator of Proinflammatory mDC Responses in #Influenza #Infection

  Abstract The severity of influenza is often driven by an excessive host immune response rather than the virus itself , yet the key molecular drivers within specific immune cells remain poorly understood. While recent single-cell RNA sequencing studies have successfully identified immune populations involved, they have largely not identified the upstream drivers modulating their pro-inflammatory functions . Here we employed an integrated single-cell co-expression network to address this gap. Our analysis identified myeloid dendritic cells (mDCs) as central to pro-inflammatory response during infection. Through a multi-layered key driver analysis, we pinpointed C-type lectin , CLEC4E as a top candidate modulating this pathological inflammatory response . The role of CLEC4E was confirmed in an independent single-cell dataset from influenza-infected patients and further validated in vivo. Pharmacological inhibition of CLEC4E in a murine influenza model significantly reduced disease s...

The #pathogenicity and multi-organ proteomic profiles of #Mpox virus #infection in SIVmac239-infected rhesus #macaques

  Abstract Mpox poses a heightened risk of severe disease and mortality among individuals with HIV , yet the molecular mechanisms and immunopathology underlying multi-organ damage caused by the mpox virus (MPXV), particularly in the context of HIV co-infection, remain poorly understood. Here, we observe increased MPXV replication, more extensive skin lesions, and impaired humoral and cellular immune responses in SIV-MPXV co-infected rhesus macaques compared to those infected with MPXV alone. Multi-organ proteomic and phosphoproteomic analyses reveals upregulation of proteins involved in immune and inflammatory pathways in skin lesions and across multiple organs, especially in immune-related tissues. Abnormal activation of DNA replication and cell cycle signaling pathways , which may contribute to enhanced viral replication, is evident in both MPXV and SIV-MPXV co-infected groups. CDK4/6 may present a potential therapeutic target to suppress MPXV replication. These comprehensive pro...

A clade 2.3.4.4b #H5N1 virus #vaccine that elicits cross-protective #antibodies against conserved domains of H5 and N1 glycoproteins

Abstract The continuous evolution and widespread dissemination of highly pathogenic avian influenza (HPAI) H5N1 viruses , particularly clade 2.3.4.4b, pose critical challenges to global pandemic preparedness . In this study, we assessed a low-dose inactivated split virus vaccine derived from clade 2.3.4.4b H5N1, formulated with an Alum/CpG adjuvant , using a preclinical mouse model . This vaccine induced potent humoral and cellular immune responses , generating high titers of cross-reactive antibodies targeting both hemagglutinin (HA) and neuraminidase (NA) glycoproteins across homologous and heterologous H5 clades. The Alum/CpG adjuvant enabled significant antigen dose-sparing while promoting a balanced Th1/Th2 immune profile . Functional analyses demonstrated strong virus neutralization , neuraminidase inhibition, and potent antibody-dependent cellular cytotoxicity activity . Additionally, the vaccine elicited robust antigen-specific CD4+ and CD8+ T cell responses and effectively con...

Intranasal #measles virus– and #mumps virus–based #SARS-CoV-2 #vaccine candidates prevent SARS-CoV-2 infection and #transmission

Significance An intranasal vaccine offers many unique advantages over traditional intramuscular-delivered vaccines . Here, we developed SARS-CoV-2 Omicron XBB.1.5 spike-based monovalent and trivalent vaccines using the live attenuated measles virus (MeV) and mumps viruses (MuV) as vectors . Intranasal immunization of hamsters and mice with monovalent and trivalent vaccines induces robust and broadly neutralizing antibodies , mucosal IgA antibodies , and lung-resident memory T cells , providing complete protection of the lung and nasal turbinate against challenges with SARS-CoV-2 WA1 and Omicron subvariants XBB.1.5, EG.5, and JN.1 . In addition, intranasal immunization efficiently blocks transmission of SARS-CoV-2 WA1 and Omicron XBB.1.5 among the hamsters by direct contact. Therefore, MeV- and MuV-based intranasal vaccines are highly promising next-generation COVID-19 vaccine candidates that can prevent virus infection and transmission. Abstract The emergence of immune-evasive SARS-CoV...

Quantifying viral #pandemic #potential from experimental #transmission studies

  Abstract In an effort to avert future pandemics, surveillance studies aimed at identifying zoonotic viruses at high risk of spilling over into humans act to monitor the "viral chatter" at the animal-human interface. These studies are hampered, however, by the diversity of zoonotic viruses and the limited tools available to assess pandemic risk. Methods currently in use include the characterization of candidate viruses using in vitro laboratory assays and experimental transmission studies in animal models. However, transmission experiments yield relatively low-resolution outputs that are not immediately translatable to projections of viral dynamics at the level of a host population. To address this gap, we present an analytical framework to extend the use of measurements from experimental transmission studies to generate more quantitative risk assessments. Specifically, we use within-host viral titer data from index and contact animals to estimate parameters relevant to tran...

A multivalent #mRNA #vaccine elicits robust immune responses and confers #protection in a murine #model of #monkeypox virus infection

Abstract Monkeypox virus (MPXV) has re-emerged globally since May 2022, posing a significant public health threat . To address this, we develop two multivalent mRNA vaccine candidates —AAL, encoding three MPXV antigens, and AALI, which combines AAL with an immune-enhancing IFN-α protein. Both vaccines are delivered via mannose-modified lipid nanoparticles to target dendritic cells . Here we show that these vaccines elicit strong antibody responses against vaccinia virus and multiple MPXV clades , induce robust memory B-cell and T-cell responses, and promote dendritic cell maturation . In mouse challenge models , both vaccines provide protection against clade IIb MPXV and vaccinia virus , significantly reducing viral loads and preventing lung damage. Immune profiling reveals enhanced B- and T-cell receptor diversity and distinct CDR3 motifs post-vaccination. These findings demonstrate the potential of using mRNA-based multivalent vaccines as an effective strategy for preventing mpox and...