Novel H5N9 virus described as hybrid of H5N1, H7N9
Chinese researchers who analyzed influenza viruses from poultry in live-bird markets say they have discovered a novel H5N9 virus that represents a hybrid of the highly pathogenic H5N1 avian flu virus and a human H7N9 virus, along with other elements.
The authors took samples in 2013 from seven chickens, a quail, and a duck at two live-bird markets in Hangzhou, a city in Zhejiang province, where human H7N9 cases had occurred, according to their Jun 17 report in the Journal of Virology. The report does not indicate that any of the birds were sick.
The team isolated 13 viruses from the samples: 1 H5N1, 2 H5N9, 4 H9N2, and 6 H7N9. By sequencing the whole genomes of the two H5N9 isolates, the researchers determined that their hemagglutinin (H) protein matched that of a 2012 H5N1 isolate from Vietnam, while their neuraminidase (N) component derived from a human H7N9 isolate from Hangzhou. They also noted that the structure of the H cleavage site is characteristic of highly pathogenic viruses. The six internal genes resembled those of H5N1, H7N9, and H9N2 viruses.
The pathogenicity of the novel virus in mammals was tested by exposing mice to various doses. Some mice exposed to the highest doses died, but mice that received lower doses didn't get sick, and the authors concluded that the virus causes low mortality in mice. They also found that the virus didn't spread from infected mice to others placed with them.
The team determined that the novel H5N9 virus prefers avian-type cell receptors, known as alpha2,3 sialic acid, rather than the human-type receptor, called alpha2,6. They said this may explain why the virus caused low mortality in mice.
The report says a highly pathogenic H5N9 virus was found in turkeys in Ontario in 1966, and low-pathogenic H5N9 strains have been found in mallards, northern pintails, and occasionally chickens in the past few decades. But the novel virus is "totally different" from those, the authors concluded.
"This newly isolated H5N9 virus is a highly pathogenic reassortant virus originating from H5N1, H7N9, and H9N2 subtypes," they wrote. "Live bird markets represent a potential transmission risk to public health and the poultry industry."
Jun 17 J Virology abstract
China, Israel report H5N1 outbreaks in poultry
China and Israel each reported more outbreaks of H5N1 avian flu, affecting about 15,000 and 17,000 domestic birds, respectively, according to reports posted by the World Organization for Animal Health (OIE).
In China, the virus hit a flock of 2,349 ornamental birds on a farm in Jiangsu province in the east and a 12,554-bird chicken farm in Guizhou province in the south, health ministry officials reported in a Jun 19 OIE report. The small flock had 2,149 cases and 1,858 deaths, while the larger farm reported 4,615 cases and 3,800 deaths.
The remainder of both flocks was culled to prevent disease spread. The outbreaks began on Jun 7 and Jun 9, respectively. Control measures, including control of wildlife reservoirs and disinfection of the sites, have been put in place.
China has now reported 20 H5N1 outbreaks since October 2014.
Jun 19 OIE report on China
The Israeli outbreak involves a 17,200-bird turkey farm in the country's Northern District near the Mediterranean Sea. One hundred and ten 10-week-old turkeys in two separate pens died from the disease, and the rest have been euthanized as a control measure.
The outbreak began May 16 and was resolved on May 18, but not reported to the OIE till Jun 20. Samples tested positive by polymerase chain reaction on May 18.
Quarantine, control of poultry movement, disinfection, and other steps have been carried out to help contain the disease, in addition to the culling. Israel had reported a separate H5N1 outbreak near the same community—Betzet—on May 12. That outbreak began on May 8.
Jun 20 OIE report on Israel