NEWS SCAN: H3N2 in pigs & humans, H7N3 Mexican strain analysis, valley fever in California prisons

May 2, 2013

Study: H3N2 flu viruses in pigs, humans appear antigenically similar
H3N2 influenza viruses infecting pigs at Ohio fairs in recent years and variant H3N2 (H3N2v) isolates in people were antigenically similar to strains circulating in commercial swine, indicating that exhibition swine can function as a bridge between commercial pigs and people, according to a study in the Journal of Virology yesterday. US and Chinese scientists antigenically analyzed 68 H3N2 isolates from pigs at fairs and compared them with H3 viruses from commercial pigs, wild birds, and dogs, as well as human seasonal H3N2 and H3N2v viruses. Their findings demonstrated that H3N2 isolates from Ohio fairs could be divided into two antigenic groups: (1) 2009 isolates and (2) isolates from 2010 and 2011. They found the same clustering in commercial swine from the same period and in human H3N2v isolates from 2010 and 2011. The researchers also noted that the human population likely has limited immunity to swine-origin H3N2 viruses such as H3N2v.
May 1 J Virol abstract

High pathogenicity of H7N3 avian flu in Mexico elucidated
The high pathogenicity of the H7N3 avian flu strain that infected chickens in Mexico last summer and led to the culling of millions of birds was likely the result of the strain's acquisition of a new extended cleavage site described in a study from Singapore yesterday in Virology Journal. The cleavage site was not present in the closest low-pathogenic precursors and appears to have been acquired naturally through recombination with host 29S ribosomal RNA, the authors found through phylogenetic, sequence, and structural analysis. Previously such an insertion has been observed only in a laboratory setting, with natural acquisition having occurred from the viral genome. The authors state, "Given the abundance of viral and host RNA in infected cells, the acquisition of a pathogenicity-enhancing extended cleavage site through a similar route by other low-pathogenic avian strains in future does not seem unlikely." The new virus can infect humans but lacks critical host-receptor adaptations that would facilitate human-to-human transmission. The authors note, however, that surveillance for future changes that could enhance such transmission is important.
May 1 Virol J abstract
Jul 3, 2012, CIDRAP News item about the strain

Valley fever may cause prisoner relocation in California
The continued persistence of valley fever, which contributed to almost three dozen inmate deaths in San Joaquin Valley prisons between 2006 through 2011 and continues to persist, has spurred a directive from a court-appointed federal overseer to move as many as 3,000 at-risk prisoners to other facilities, according to Reuters. The fungal infection, known medically as coccidioidomycosis, is a special risk for African Americans, those of Filipino heritage, those with compromised immune systems, those over 55 years old, and those with diabetes, the story said. The prisons involved are Pleasant Valley State and Avenal State. The federal receiver, J. Clark Kelso, calls the state's response so far "anemic," and an expert hired by inmates' attorneys said the infection rate at Pleasant Valley was "1,000 times the rate for Californians generally." A Los Angeles Times story yesterday said the Centers for Disease Control and Prevention is investigating. The infection can cause cough, fever, chest pain, and muscle aches.
May 1 Reuters story
May 1 LA Times story

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