In a related development, a Chinese research team reported finding H7N9 in poultry and environmental samples from all of 12 markets identified in investigations of 10 human H7N9 infections detected in and around Hangzhou in Zhejiang province last April.
Their tests also showed that the environments were heavily contaminated by both H7N9 and H9N2 viruses, with some samples also yielding H5N1.
They used reverse-transcription polymerase chain reaction (RT-PCR) testing and high-throughput next-generation sequencing.
The results provide direct evidence that H9N2 coexisted with the novel H7N9 virus in poultry markets linked to human cases, suggesting that the H9N2 virus made recent and ongoing contribution to H7N9’s evolution, the team wrote.
They also noted that there were no H9N2 detections among the 10 patients.
Earlier genetic studies of H7N9 had found that internal genes of the new virus clustered with at least two H9N2 viruses from China.