Biology subjects

Escobedo, R. A.

Publications and source records attributed to Escobedo, R. A..

4 recordsLinked to original sources

bioRxiv2025

A Live Attenuated Vaccine Candidate against Emerging Highly Pathogenic Cattle-Origin 2.3.4.4b H5N1 Viruses

Influenza viruses present a significant public health risk, causing substantial illness and death in humans each year. Seasonal flu vaccines must be updated regularly, and their effectiveness often decreases due to mismatches with circulating strains. Furthermore, inactivated vaccines do not provide protection against shifted influenza viruses that have the potential to cause a pandemic. The highly pathogenic avian influenza H5N1 clade 2.3.4.4b is prevalent among wild birds worldwide and is causing a multi-state outbreak affecting poultry and dairy cows in the United States (US) since March 2024. In this study, we have generated a NS1 deficient mutant of a low pathogenic version of the cattle-origin human influenza A/Texas/37/2024 H5N1, namely LPhTXdNS1, and validated its safety, immunogenicity, and protection efficacy in a prime vaccination regimen against wild-type (WT) A/Texas/37/2024 H5N1. The attenuation of LPhTXdNS1 in vitro was confirmed by its reduced replication in cultured cells and inability to control IFN{beta} promoter activation. In C57BL/6J mice, LPhTXdNS1 has reduced viral replication and pathogenicity compared to WT A/Texas/37/2024 H5N1. Notably, LPhTXdNS1 vaccinated mice exhibited high immunogenicity that reach its peak at weeks 3 and 4 post-immunization, leading to robust protection against subsequent lethal challenge with WT A/Texas/37/2024 H5N1. Altogether, we demonstrate that a single dose vaccination with LPhTXdNS1 is safe and able to induce protective immune responses against H5N1. Both safety profile and protection immunity suggest that LPhTXdNS1 holds promise as a potential solution to address the urgent need for an effective vaccine in the event of a pandemic for the treatment of infected animals and humans. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=143 HEIGHT=200 SRC="FIGDIR/small/646033v2_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1ca0d0borg.highwire.dtl.DTLVardef@1e5232org.highwire.dtl.DTLVardef@a6694corg.highwire.dtl.DTLVardef@14b0832_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2025

A Human H5N1 Influenza Virus Expressing Bioluminescence for Evaluating Viral Infection and Identifying Therapeutic Interventions

A multistate outbreak of highly pathogenic avian influenza virus (HPAIV) H5N1 in dairy cows was first reported on March 25, 2024, in the United States (US), marking the first discovery of HPAIV H5N1 in cattle. Soon after, a dairy worker on an affected dairy farm became the first human case linked directly to this outbreak. Studies with influenza A virus (IAV) require secondary methods to detect the virus in infected cells or animal models of infection. We modified the non-structural (NS) genome segment of the human A/Texas/37/2024 (HPhTX) H5N1 virus to create a recombinant virus expressing nanoluciferase (HPhTX NSs-Nluc), enabling the tracking of virus in cultured cells and mice via in vitro, ex vivo, and in vivo imaging systems (IVIS). In vitro, HPhTX NSs-Nluc showed growth and plaque characteristics similar to its wild-type (WT) counterpart. In vivo, HPhTX NSs-Nluc allowed tracking viral infection in the entire animals and in the organs of infected animals using in vivo and ex vivo IVIS, respectively. Importantly, the morbidity, mortality, and replication titers of HPhTX NSs-Nluc were comparable to those of the WT HPhTX. In vitro, HPhTX NSs-Nluc was inhibited by Baloxavir acid (BXA) to levels observed with WT HPhTX. We also demonstrate the feasibility of using HPhTX NSs-Nluc to evaluate the antiviral activity of BXA in vivo. Our findings support that HPhTX NSs-Nluc represents an excellent tool for tracking viral infections, including the identification of prophylactics or therapeutics for the treatment of the HPAIV H5N1 responsible of the outbreak in dairy cows.

microbiology↗

bioRxiv2025

Identification of Amino Acid Residues Responsible for Differential Replication and Pathogenicity of Avian Influenza Virus H5N1 Isolated from Human and Cattle in Texas, US

Highly pathogenic avian influenza viruses (HPAIV) pose a serious public health concern. In March 2024, a first-time outbreak of HPAIV H5N1 in dairy cattle herds was reported in the United States (US). Since then, the virus has continued to spread in cattle herds and spilt over into humans. We recently showed that the first human isolate reported in the US in Texas (HPhTX) from a dairy worker in an affected cattle farm has enhanced replication kinetics and pathogenicity in mice compared to a closely related bovine isolate (HPbTX). However, the molecular determinants of differential pathogenicity have not yet been identified. Herein, we show that HPhTX has enhanced polymerase activity, compared with HPbTX, in human cells and that the polymerase basic 2 (PB2) protein is the main factor responsible for this difference. Through single and combined site-directed mutagenesis and swapping the three amino acids different between HPhTX and HPbTX, we found that PB2 mutation E627K is the major contributor to the enhanced polymerase activity of HPhTX. E362G substitution in HPhTX PB2 affected the polymerase, although to a lesser extent than E627K. Moreover, M631L mutation in HPhTX PB2 enhanced polymerase activity. Rescue of a loss-of-function recombinant HPhTX (rHPhTX) containing mutations at residues 627 and 362, alone or in combination, revealed a contribution of PB2 E362G and K627E in morbidity, mortality, and viral replication as compared to rHPhTX wild-type (WT), and significantly reduced viral pathogenicity to levels comparable to rHPbTX WT. These findings indicate that HPAIV H5N1 of cattle origin isolated from the first human case has post-transmission amino acid changes that increase viral replication in human cells and pathogenicity in mice.

microbiology↗

bioRxiv2024

Replication Kinetics, Pathogenicity and Virus-induced Cellular Responses of Cattle-origin Influenza A(H5N1) Isolates from Texas, United States

The host range of HPAIV H5N1 was recently expanded to include ruminants, particularly dairy cattle in the United States. Shortly after, human H5N1 infection was reported in a dairy worker in Texas following exposure to infected cattle. Herein, we rescued the cattle-origin influenza A/bovine/Texas/24-029328-02/2024(H5N1, rHPbTX) and A/Texas/37/2024(H5N1, rHPhTX) viruses, identified in dairy cattle and human, respectively, and their low pathogenic forms, rLPbTX and rLPhTX, with monobasic HA cleavage sites. Intriguingly, rHPhTX replicated more efficiently than rHPbTX in mammalian and avian cells. Still, variations in the PA and NA proteins didnt affect their antiviral susceptibility to PA and NA inhibitors. Compared to rHPbTX and rLPbTX, the rHPhTX and rLPhTX exhibited higher pathogenicity and efficient replication in infected C57BL/6J mice. The lungs of rHPhTX-infected mice produced higher inflammatory cytokines/chemokines than rHPbTX-infected mice. Our results highlight potential risk of HPAIV H5N1 virus adaptation in human and/or dairy cattle during the current multistate/multispecies outbreak.

microbiology↗