Overview on the Surveillance of Avian-orgin Coronaviruses
Coronaviruses belong to Nidovirales,family Coronaviridae,Orthocoronavirinae,which are divided into four genera:Alphacoronavirus,Betacoronavirus,Gammacoronavirus and Deltacoronavirus,and can infect many animals including humans. Among them,Alphacoronavirus mainly infects humans and pigs,dogs,cats,bats,etc.,Betacoronavirus mainly infects humans,cattle,horses,pigs,mice,bats and other mammals,and Gammacoronavirus mainly infects chickens,turkeys,ducks,geese and other birds,Deltacoronavirus mainly infects wild birds and pigs. The emerging 2019-nCoV causing novel coronavirus pneumonia(NCP)outbreak in China belongs to the Betacoronavirus of Coronaviridae. Coronaviruses that can infect birds are mainly from the Gammacoronavirus and Deltacoronavirus of Coronaviridae.
Coronaviruses isolated from poultry such as avian infectious bronchitis virus(IBV)are all Gammacoronavirus. In the avian coronaviruses,IBV is more harmful to the poultry. In addition,duck coronavirus,goose coronavirus and pigeon coronavirus were also detected. Some wild birds can be infected with Deltacoronavirus(such as thrush coronavirus HKU12,etc.). Since 2013,a total of 5 249 poultry samples from 17 provinces in China have been detected by China Animal Health and Epidemiology Center,a total of 446 avian infectious bronchitis viruses,277 of novel duck coronaviruses and novel pigeon coronaviruses have been detected. The positive rates of avian infectious bronchitis virus,novel duck coronavirus,and novel pigeon coronavirus were 8.50%,2.04% and 3.24%,respectively.
Analysis of the relationship between 2019-nCoV and avian coronavirus found that the nucleotide homology between 2019-nCoV and known avian-orgin coronaviruses was quite lower compared with mammal-origin coronaviruses. Evolutionary analysis based on the conserved region of the coronavirus 1ab gene shows that 2019-nCoV is far from avian coronavirus. According to the above analysis results,the possibility of 2019-nCoV originating from the known avian-origin coronaviruses can be preliminarily ruled out.