Burrough, E. | Search bioRxiv

bioRxiv2024

Highly Pathogenic Avian Influenza A (H5N1) clade 2.3.4.4b Virus detected in dairy cattle

The global emergence of highly pathogenic avian influenza (HPAI) A (H5N1) clade 2.3.4.4b viruses poses a significant global public health threat. Until March 2024, no outbreaks of this virus clade had occurred in domestic cattle. We genetically characterize HPAI viruses from dairy cattle showing an abrupt drop in milk production. They share nearly identical genome sequences, forming a new genotype B3.13 within the 2.3.4.4b clade. B3.13 viruses underwent two reassortment events since 2023 and exhibit critical mutations in HA, M1, and NS genes but lack critical mutations in PB2 and PB1 genes, which enhance virulence or adaptation to mammals. The PB2 E627K mutation in a human case underscores the potential for rapid evolution post-infection, highlighting the need for continued surveillance to monitor public health threats.

microbiology↗

bioRxiv2019

Genetic characterization of Streptococcus equi subspecies zooepidemicus associated with high swine mortality in United States

High mortality events due to Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) in swine have not previously been reported in the United States. In September and October 2019, outbreaks with swine mortality up to 50% due to S. zooepidemicus septicemia were reported in Ohio and Tennessee. Genomic epidemiological analysis revealed that the eight outbreak isolates were clustered together with ATCC 36246, a Chinese strain caused outbreaks with high mortality, also closely related to three isolates from human cases from Virginia, but significantly different from an outbreak-unrelated swine isolate from Arizona and most isolates from other animal species. Comparative genomic analysis on two outbreak isolates and another outbreak-unrelated isolate identified several genomic islands and virulence genes specifically in the outbreak isolates only, which are likely associated with the high mortality observed in the swine population. These findings have implications for understanding, tracking, and possibly preventing diseases caused by S. zooepidemicus in swine.

microbiology↗