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Rabbit haemorrhagic disease (RHD) is an acute fatal disease caused by the Lagovirus rabbit haemorrhagic disease virus (RHDV), which was first reported in 1984 in China. Strains of two different genotypes (GI.1a and GI.1c) have been detected in China to date. In 2010, a new RHDV variant with a unique genetic and antigenic profile was identified in France, designated RHDV2, which rapidly spread throughout continental Europe and nearby islands. Here, we report the first outbreak of RHD induced by RHDV2 (GI.2) in rabbit farms in the Sichuan province of China. We conducted haemagglutination tests and phylogenetic analysis of the new RHDV isolate SC2020/04, which was identified as a non-haemagglutinating strain belonging to the RHDV2 (GI.2) genogroup. Considering the serious risk of RHDV2 to the Chinese rabbit industry, the circulation of RHDV2 in the population should be carefully monitored in China., (© 2020 The Authors Veterinary Medicine and Science Published by John Wiley & Sons Ltd.)

During the past years epizootic outbreaks of mucoid enteropathy syndrome (MES) disease have emerged and spread rapidly in rabbit farms in East China causing great economic losses. To investigate the nature and evolution of the disease, two trials were conducted in an attempt to reproduce the disease and to assess the microbiota cecal profile changes associated with the disease. In the first trial, twenty 6-week-old New Zealand White healthy rabbits were assigned randomly to one of two treatments: 1) Inoculation with 2.0 mL of cecal content (inoculum) from dead rabbits affected with MES; 2) No inoculation or control group. In the second trial, V3 - V4 regions of 16S ribosomal genes from three virulent (MES) and two non-virulent (healthy) cecal samples were amplified and sequenced for microbiota genomic characterization. The mucoid enteropathy syndrome was reproduced using a virulent cecal material (inoculum). The mortality rates for treatments 1 and 2 were 70% and 0%, respectively. Clinical signs and gross lesions of affected rabbits consisted of bloated abdomen, cecal impaction, presence of variable amounts of gelatinous mucus particularly in the colon, mucus excretion and diarrhea of low intensity. The disease that emerged in China is similar to the epizootic rabbit enteropathy (ERE) described in Europe. However, microbiota cecal changes associated with the disease differed from those in ERE. Here, a comprehensive analysis of mucoid enteropathy syndrome disease is presented, which should be carefully monitored., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

During infection host histo-blood group antigens (HBGAs) act as attachment factors that interact with rabbit hemorrhagic disease virus (RHDV) and participate in the infectious process. In the present study, baculovirus expressing recombinant RHDV capsid protein (VP60r) as a vaccine immunogen was used to test its antigenicity and immunogenicity via immunization experiments. Each group of rabbits immunized with VP60r was found to be fully protected against RHDV challenge. The duration of immunity of the vaccine following the inoculation of a single dose was determined to be at least 240 days. RHDV-specific humoral responses in antisera from inoculated rabbits were analyzed using VP60r virus-like particle (VLP)-based ELISA. Anti-VP60-specific antibody was produced by 7 days post-primary immunization. Following this stage, the levels of this antibody increased steadily, peaking at 90 days and maintaining a high level until 240 days. We developed a synthetic carbohydrate assay to detect blockage in attachment of RHDV VLPs to HBGAs by the rabbit antisera. On day 7 post-immunization, serum samples were demonstrated to block the binding of H type 2 to RHDV VLPs, with a blocking rate of almost 60%, a value that then increased steadily over time. From day 60 to day 240 post-immunization, serum samples completely blocked the binding of H type 2 to RHDV VLPs, with a blocking rate of almost 100%. This indicated that VP60-induced antibodies neutralize the interaction of RHDV with HBGAs.