New genetic and evolutionary trends emerge in rabies virus among animals in northern China
Website news Recently, the innovative team for pathogens and immunity of special animals at the Institute of Special Animal and Plant Sciences of the Chinese Academy of Agricultural Sciences, in a latest study of the molecular evolution of animal rabies virus (RABV) in northern China and parts of Northeast Asia, found that the China-I lineage virus, once mainly prevalent in the south, has begun to spread northward to the northernmost tip of China, where RABV strains of multiple lineages converge and circulate together, increasing the complexity of the epidemic and the difficulty of control. The related research results were published in the world-renowned journal Infection, Genetics and Evolution.
In recent years, the number of rabies cases has surged in South Korea, Mongolia and the northern provinces of China, and the epidemic has shown a trend of spread and diffusion, becoming an important feature of the regional epidemic of rabies. The institute's innovative team carried out cooperative research with related units and collected multiple rabies samples in northern China, including from dogs, fallow deer, sika deer, blue foxes, steppe foxes, camels, cattle and raccoon dogs, and sequenced all or part of the genes of the viruses. The study found that the RABV epidemic strains in northern China include two types, dog-derived and wild animal-derived; the dog-derived strains include China-I and China-II lineage strains, while the wild animal-derived strains are mainly the Steppe-type and Arctic-like types.
Through research on the molecular evolution of Arctic-like lineage viruses in Northeast Asia, it was found that their most recent common ancestor can be traced back to the period from 1757-1904, while the Arctic-like strains currently circulating in northern China belong evolutionarily to the Arctic-like 1b (AL-1b) subgroup, and the origin of this group of viruses can be traced back as early as the 1960s. Evolutionarily, the RABV isolates from northern China are most closely related to epidemic strains in the Russian Far East, and relatively more distantly related to isolates from South Korea and Mongolia. Further analysis showed that Arctic-like rabies viruses in northern China may have been carried from Russia by raccoon dogs and introduced into China via Khabarovsk (Boli). Analysis of the viral N protein and G protein genes found that this lineage of virus is currently affected by natural selection, but there are no traces of recombination in these two genes.
In addition, the innovative team's systematic study of the Inner Mongolia fallow deer isolate IMDRV-13 found that this strain has strong pathogenicity in both suckling mice and adult mice, and whole-genome analysis showed that this strain belongs to the dog rabies virus China-I lineage. Notably, a mutation I338T at antigenic site III on the glycoprotein G of this strain led to the addition of an N-glycosylation site at that position, which may have a potential impact on the virulence and host adaptability of the virus.
