Philippine Carabao Center

H9N2 low-pathogenic avian influenza viruses (LPAIV) represent an ongoing zoonotic threat due to their enzootic circulation in poultry, reassortment capacity, and increasing human transmission events. This study characterized three H9N2 isolates recovered from apparently healthy poultry in a Changchun live poultry market (September-November 2022) that exhibited unprecedented genetic and phenotypic characteristics indicating enhanced zoonotic risk. Phylogenetic analysis showed a complex mosaic genome combining segments from four distinct lineages: HA from the BJ/94-like lineage (human-associated), PB1/NP/NS from the F98-like lineage, NA from the FJ/30-C-like branch, and PB2/M genes from the G1-like lineage. Bayesian molecular clock analysis estimated the most recent common ancestor at February 2022, with HL55 and HL56 diverging by May 2022, indicating rapid local viral evolution. All isolates retained hallmark LPAIV characteristics (monobasic HA cleavage site, zero intravenous pathogenicity index in chickens). However, receptor-binding assays demonstrated a critical divergence among the isolates: while HL45 exhibited exclusive avian α2-3 receptor preference, both HL55 and HL56 retained strong avian receptor binding while additionally showing measurable affinity for human α2-6 receptors-a dual-binding phenotype associated with enhanced zoonotic potential. Most significantly, the HL55 isolate successfully infected BALB/c mice without prior adaptation, causing transient upper respiratory tract replication, moderate weight loss (~9.2%), and mild disease without mortality or systemic dissemination. These findings demonstrate that the direct mammalian infectivity of this specific mosaic H9N2 lineage adds to the growing body of evidence regarding the zoonotic potential of contemporary H9N2 variants. The presence of known mammalian-adaptation markers (PB2 A588V, NA stalk deletion, HA position 226 leucine), combined with demonstrated dual receptor-binding capacity and inherent mammalian infectivity, underscores the accelerated evolutionary trajectory of H9N2 viruses toward increased zoonotic competence. These findings warrant intensified surveillance in live poultry markets, comprehensive antigenic characterization of emerging variants, and enhanced biosecurity measures to mitigate the risk of spillover events and potential pandemic emergence.

Background: Food safety is essential for public health. Food products from animals and farm environments can serve as vehicles for the transmission of antibiotic-resistant bacteria and resistance genes to humans. Aim: This study aimed to identify the phenotypic and genotypic resistance profiles of multidrug-resistant Escherichia coli isolated from dairy buffalo farms. Methods: A total of 103 E. coli isolates were recovered from soil samples from a previous survey of dairy buffalo farms. Phenotypic characterization of these isolates was performed using antibiotic susceptibility test through microbroth dilution, while molecular analysis employed polymerase chain reaction (PCR) and multilocus sequence typing (MLST) Results: Antibiotic sensitivity testing revealed that 19.41% (20/103) of the environmental E. coli isolates exhibited chloramphenicol (CHL), and minocycline (MNO). Of these resistant isolates, four were identified as multidrug-resistant (MDR), with AMC-TIC-PIP-TET-CHL as the most common resistance pattern. Molecular assays also confirmed the presence of resistance determinants, including blaTEM for beta-lactam resistance, and tetA for TET resistance, in these MDR E. coli. These MDR environmental isolates also belong to the same E. coli clones found in humans based on Conclusion: The detection of MDR environmental E. coli in dairy buffalo farms in the country highlights a multifaceted hazard that can spread through livestock production systems, enter the food supply chain, and pose zoonotic disease risks.

Influenza D virus (IDV), an emerging orthomyxovirus with zoonotic potential, infects diverse hosts, causes respiratory disease, and remains poorly characterized in China despite its global expansion. From October 2023 to January 2025, we collected 563 nasal swabs from cattle across 28 farms in Jilin Province, Northeast China, and identified seven IDV-positive samples (1.2%), recovering two viable isolates (JL/YB2024 and JL/CC2024). Full-genome sequencing revealed complete, stable seven-segment genomes with high nucleotide identity (up to 99.9%) to contemporary Chinese D/Yamagata/2019 strains and no evidence of reassortment. Maximum-likelihood and time-resolved Bayesian phylogenies of 231 global hemagglutinin-esterase-fusion (HEF) sequences placed the Jilin isolates within the East Asian D/Yamagata/2019 clade and traced their most recent common ancestor to approximately 2017 (95% highest posterior density: 2016-2018), suggesting a cross-border introduction likely associated with regional cattle movement. No IDV was detected in parallel surveillance of swine, underscoring cattle as the principal reservoir and amplifying host. Bayesian skyline analysis demonstrated a marked decline in global IDV genetic diversity during 2020-2022, coinciding with livestock-movement restrictions imposed during the COVID-19 pandemic. Collectively, these findings indicate that IDV circulation in China is sporadic and geographically localized, dominated by the D/Yamagata/2019 lineage, and shaped by multiple independent incursions rather than a single emergence. Both the incorporation of IDV diagnostics into routine bovine respiratory disease surveillance and cattle-import quarantine programs, and the adoption of a One Health framework to monitor potential human spillover and future viral evolution, were recommend.

Newcastle disease (ND), caused by virulent strains of the Newcastle disease virus (NDV), is a highly contagious disease that poses significant economic burdens on the global poultry industry. The DNA damage response (DDR) is a critical cellular mechanism that detects and repairs genomic damage to maintain cellular integrity. While viral infections are known to modulate DDR pathways to either inhibit or enhance viral replication, the interaction between NDV and host DDR remains largely underexplored. Here, we demonstrate that NDV infection induces significant DNA damage in DF-1 cells and activates DDR signaling, primarily via the ataxia-telangiectasia mutated (ATM) kinase pathway, in a manner dependent on active viral replication. Pharmacological inhibition of ATM kinase, but not ataxia telangiectasia and Rad3-related (ATR) kinase, significantly suppresses NDV replication, alleviates virus-induced G1-phase cell cycle arrest, and modulates the host immune response. Moreover, short interfering RNA (siRNA)-mediated knockdown of Chk2 markedly reduced viral M gene expression and progeny production, indicating that Chk2 is required for efficient NDV replication. These findings suggest that NDV exploits the ATM–Chk2 DDR pathway to establish a replication-favorable environment. Our study provides new insights into NDV pathogenesis and highlights potential targets for antiviral interventions.

This study sought to optimize the urea and molasses concentrations and rice straw preparation to improve the nutritional value and quality of silage for ruminants. It consisted of four (4) parts and was conducted sequentially: 1) screening and characterization, 2) optimization using Response Surface Methodology (RSM), 3) numerical optimization, and 4) experimental validation. Three (3) factors were considered for the optimization protocol: 1) urea concentration ranging from 1% to 6%; 2) molasses concentration from 1% to 8%; and (3) rice straw preparations as un-chopped and chopped. The results indicated that varying molasses concentration from 1% to 8% did not significantly affect dry matter (DM) and crude protein (CP) degradability. Additionally, rice straw preparation showed no significant effect on all responses at a low urea concentration (1%). However, at a high urea concentration (6%), chopped rice straw resulted in significantly higher values for all responses than un-chopped rice straw. The optimized conditions were found to be 4.39% urea concentration for chopped and 3.61% for un-chopped rice straw. Using chopped rice straw at the optimized urea concentration improved DM, CP, and organic matter (OM) degradability compared to un-chopped rice straw. Thus, the utilization of optimized levels of urea combined with molasses ranging from 1% to 8% led to higher-quality rice straw silage.