Human infection with a novel, highly pathogenic avian influenza A (H5N6) virus: Virological and clinical findings.

Summary Background and objectives Severe infection with avian influenza A (H5N6) virusin humans was identified first in 2014 in China. Before that, it was unknown or unclear if the disease or the pathogen affected people. This study illustrates the virologicaland clinical findings of a fatal H5N6 virusinfection in a human patient. Methods We obtained and analyzed the clinical, epidemiological, and virologicaldata from the patient. Reverse transcription polymerase chain reaction (RT-PCR), viral culture, and sequencing were conducted for determination of the causative pathogen. Results The patient, who presented with fever, severe pneumonia, leucopenia, and lymphopenia, developed septic shock and acute respiratory distresssyndrome (ARDS), and died on day 10 after illness onset. A novel reassortantavian-origin influenza A (H5N6) viruswas isolated from the throat swabor trachea aspirate of the patient. The viruswas reassortedwith the HA gene of clade 2.3.4.4 H5, the internal genes of clade 2.3.2.1 H5, and the NA gene of the H6N6 avian virus. The cleavage site of the HA gene contained multiple basic amino acids, indicating that the novel H5N6 viruswas highly pathogenic in chicken. Conclusions A novel, highly pathogenic avian influenzaH5N6 viruswith a backbone of H5N1 virusacquired from the NA gene from the H6N6 virushas been identified. It caused human infection resulting in severe respiratory disease.