Outbreak of the disease caused by the rabbit hemorrhagic disease virus 2 in the Russian Federation

Abstract

Relevance . Rabbit haemorrhagic disease virus type 2 (RHDV-2, GI2,) was first detected in 2010 in France and quickly spread across еuropean countries. Unlike strains of the first genogroup, RHDV GI2 also affects rabbits under 2 months old, as well as various types of hares. In addition, RHDV GI2 causes the death of rabbits vaccinated with vaccines based on type 1 hemorrhagic disease viruses. The rabbit hemorrhagic disease virus 2 (RHDV-2) was detected during an outbreak of the disease, characterized by the sudden death of rabbits of different age groups, in the summer of 2019 in a private farm in the Tula region, Russia. The purpose of this study was to detect and obtain the molecular genetic characteristics of the pathogen. Methods. The ELISA was used for the detection of RHDV antigen in samples of pathological material from dead animals. The presence of RHDV RNA was determined by the method of reverse transcription/polymerase chain reaction (RT/PCR) using pair of specific primers for the regions of the VP1 and VP60 genes. The Sanger sequencing reaction was performed and obtained nucleotide sequences were analyzed. Results . Antigen and RNA of the rabbit haemorrhagic disease virus were detected by ELISA and RT-PCR in laboratory studies of the liver of dead animals. Analysis of the nucleotide sequence of a 470 base pair region of the genome, containing the 5 ‘terminal region of the VP1 gene and the 3’ terminal region of the VP60 gene, showed that the detected virus belongs to RHDV-2. Phylogenetic analysis revealed that the closest to it were the sequences of RHDV-2 from the USA, France and Poland isolated in the 2016–2020. The VP60 amino acid sequence of detected virus contained the A46T substitution (alanine for threonine at position 46), which can affect the conformation of the capsid protein and, as a consequence, the antigenic structure of the virus.