New trend of genetic evolution of animal rabies virus in northern China

A few days ago, the special animal pathogen and immunity innovation team of the Special products Research Institute of the Chinese Academy of Agricultural Sciences found that the China-I pedigree virus, which was once prevalent mainly in the south, has begun to spread northward to the northernmost tip of China, where multiple pedigree RABV strains converge and mix. It increases the complexity of the epidemic and the difficulty of control. The relevant research results are published in the world-famous journal infection, Genetics and Evolution (Infection Genetic and Evolution).

In recent years, the number of rabies cases has increased sharply in South Korea, Mongolia and northern provinces of China, and the epidemic situation shows a trend of spread, which has become an important feature of rabies epidemic in the region. The innovation team of the institute carried out cooperative research with relevant units, and collected a number of rabies materials in northern China, including dogs, deer, sika deer, blue fox, prairie fox, camel, cow, razor, etc., and sequenced all or part of the genes of the virus. It was found that the epidemic strains of RABV in northern China included canine and wild animal strains, canine strains included China-I and China- Ⅱ strains, and wild animal strains were mainly Steppe-type and Arctic-like-like strains.

Through the study on the molecular evolution of Arctic-like pedigree viruses in Northeast Asia, it is found that the most recent common ancestor can be traced back to 1757-1904, while the Arctic-like strains prevalent in northern China belong to Arctic-like 1b (AL-1b) subgroup in evolution, and the origin of this group of viruses can be traced back to the 1960s. Evolutionarily, the RABV isolates from northern China are closely related to Russian far East strains, and relatively distant from Korea and Mongolia. Further analysis shows that Arctic-like rabies virus in northern China may be carried from Russia and introduced into China through Khabarovsk (Bali). According to the analysis of N protein and G protein genes of the virus, it was found that the pedigree virus was affected by natural selection, but there was no trace of recombination of these two genes.

In addition, the systematic study of Inner Mongolia deer isolate IMDRV-13 by the innovative team found that the strain had strong pathogenicity in both suckling and adult mice, and the whole genome analysis showed that the strain belonged to the China-I lineage of canine rabies virus. It is worth noting that a mutation I338T of the antigenic site Ⅲ on glycoprotein G of the strain leads to the addition of an N-glycosylation site at this site, which may have a potential effect on the virulence and host adaptability of the virus.