Skip to main content

Different #genetic #determinants for high #virulence, #transmission and #replication of high pathogenicity #H7N7 avian #influenza virus in #turkeys and #chickens

Abstract

High pathogenicity (HP) avian influenza viruses (AIV) generally evolve from low pathogenicity (LP) precursors after transmission from wild birds to chickens (Gallus gallus domesticus) and turkeys (Meleagris gallopavo), causing severe economic losses worldwide. Turkeys are more susceptible to AIV infection than chickens and are considered potential bridging hosts that facilitate the emergence of HPAIV. Beyond the polybasic cleavage site (pCS) in hemagglutinin (HA), little is known about other virulence determinants of HPAIV in these species. In 2015, HPAIV H7N7 and its LP ancestor were isolated from the same chicken farm, which differed by 16 nonsynonymous mutations across all eight gene segments, in addition to the pCS. Here we identify the genetic determinants, including the pCS, that contributed to the HPAIV H7N7 virulence, transmission, replication, and tissue distribution in chickens and turkeys. Notably, the non-structural (NS1) or matrix (M) proteins’ encoding segments in turkeys, or NS segment in chickens, rendered viruses as virulent and transmissible as the original HPAIV. Endotheliotropism, observed exclusively in chickens, was driven by the pCS and, to a lesser extent, the neuraminidase (NA). In vitro, the M2-V68L mutation influenced NS1 expression and virus morphology in chicken and turkey cells. Additionally, HPAIV NS1 enhanced polymerase activity and effectively suppressed interferon induction, a process further modulated by M2-V68L. These findings underscore the critical role of turkeys as a “hub” in the evolution of HPAIV from LP precursors, offering crucial insights into the genotypic and phenotypic factors that facilitate viral adaptation in different poultry species.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.03.18.643940v1?rss=1

____

Comments

Popular posts from this blog

#USA, APHIS Confirms {Avian #Influenza #H5N1} #D11 #Genotype in Dairy #Cattle in #Nevada

On January 31, 2025, the USDA Animal and Plant Health Inspection Service (APHIS) National Veterinary Services Laboratories (NVSL) confirmed by whole genome sequence the first detection of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b, genotype D1.1 in dairy cattle .  This confirmation was a result of State tracing and investigation, following an initial detection on silo testing under the USDA’s National Milk Testing Strategy (NMTS) in Nevada.  USDA APHIS continues to work with the Nevada Department of Agriculture by conducting additional on-farm investigation, testing, and gathering additional epidemiological information to better understand this detection and limit further disease spread.  This is the first detection of this virus genotype in dairy cattle (all previous detections in dairy cattle have been HPAI H5N1 clade 2.3.4.4b, genotype B3.13 ).  Genotype D1.1 represents the predominant genotype in the North American flyways this past fall an...

#USA, After #Birdflu Detected in Local #Cat, County #Health Officials Say #Pet Owners Should Contact Veterinarian When Their Pets are Sick

Redwood City — State veterinary and health officials have confirmed a case of H5N1 (bird flu) in a domestic stray cat in San Mateo County.  The infection, which is not related to the recent instance of bird flu in a backyard flock , was found in a stray cat in Half Moon Bay that had been taken in by a family .  When it showed symptoms, they took it to Peninsula Humane Society, whose veterinarians examined it and requested testing. Lab results confirmed H5N1.  It is not known how the cat was infected and it was euthanized due to its condition. Cats may be exposed to bird flu by consuming infected bird , being in environments contaminated with the virus and consuming unpasteurized milk from infected cows or raw food. Inside domestic animals, such as cats and dogs, that go outside are also at risk of infection.​​​​​​​ According to the Centers for Disease Control and Prevention, the risk of cats spreading H5N1 to people is extremely low, though it is possible for cats to spre...

#USA, Novel #Influenza A #H5N1 Virus: One Pediatric Case in #California {FluView}

 {Excerpt} One confirmed human infection with influenza A(H5) virus was reported to CDC this week. To date, human-to-human transmission of influenza A(H5) virus has not been identified in the United States. This case was reported by the California Department of Public Health and occurred in a child less than 18 years old with no known contact with influenza A(H5N1) virus-infected animals or humans . The investigation into the source of infection for this case is ongoing , and no human-to-human transmission has been identified. A specimen from the individual was tested at a public health laboratory using the CDC influenza A(H5) assay before being sent to CDC for further testing. The specimen was positive for influenza A(H5) virus using diagnostic RT-PCR at CDC. Additional analysis including genetic sequencing is underway. In response to this detection, additional case investigation and contact monitoring are being conducted by public health officials in California. There have now be...