The Investigation Of The Prevalence Of Ranavirus In Rana Dybowskii In Heilongjiang Province And Viral Genotype Analysis

Amphibian populations have dramatically declined globally over the past decades, including a number of species extinction. Many factors may cause the declination such as ultraviolet radiation, habitat damage, changes of climate and interactions among these factors. However, the new infectious diseases-lridoviruses are the important and direct causes for some of the local population extinction.In this study, we collected Rana dybowskii in summer and autumn in four areas of Heilongjiang Province. We collected 180 adults in autumn and 120 tadpoles in summer. Iridoviruses were detected in Rana dybowskii by PCR assay and homology comparison of sequences. Meanwhile the prevalence of iridovirus in Rana dybowskii in Heilongjiang Province was reported. Survey results showed that, in Heilongjiang province, ranaviruses existed in the population of Rana dybowskii and the infection rates among different regions and different seasons were obviously different. The positive rate was 5% in autumn, with the positive rate in four areas, respectively:Hebei Forest Bureau 4.4%, Dongfanghong Forest Bureau 5.9%, Heihe Forestry Bureau 8.9% and virus-negative in Acheng city. The positive rate was 42.5% in summer, with the positive rate in four areas, respectively:Hebei Forest Bureau 66.7%, Dongfanghong Forest Bureau 22.3%, Heihe Forestry Bureau 80% and virus-negative in Acheng city. We presumed that these differences were associated with the developmental stage and different habitats.We conducted restriction enzyme analysis for the obtained viruses in the autumn survey. Four kinds of restriction enzyme were chosen:PfIMâ… , Fnu4Hâ… , Hincâ…¡and Accâ… . The digestion results showed that 9 strains of virus were the same and were consistent with the results of FV3, the representative species of Ranavirus. These results suggested that the viruses in the population of Rana dybowskii were identical, and were closely related to FV3.This study is the first survey of Ranavirus in the population of Rana dybowskii, and this is the first survey of virus prevalence in wild amphibian population in China. The results of this survey were significant for assessing the health and conservation status of native amphibian fauna in the face of constantly changing environmental factors. Our results significantly expand our scope of the epidemiology of ranavirus in China and highlight the necessity for the collaboration of local and international scientists to address the risks to the health and survival of native, Chinese wildlife. In addition, the results of viral genotype analysis suggest that it is necessary to strengthen the conservation of amphibian population and amphibian trade regulation.