Recombinant Lactobacillus casei Expressing Capsid Protein VP60 can Serve as Vaccine Against Rabbit Hemorrhagic Disease Virus in Rabbits

Wang, Li; Xia, Tian; Guo, Tiantian; Ru, Yi; Jiang, Yanping; Cui, Wen; Zhou, Han; Qiao, Xinyuan; Tang, Lijie; Xu, Yigang; Li, Yijing

Rabbit hemorrhagic disease (RHD), characterized by severe necrotizing hepatitis and disseminated intravascular coagulation in the liver, spleen, kidney and other solid organs, is a highly contagious and lethal infection in rabbits [1, 2] . RHD is peracute and often lethal hepatitis caused by the rabbit caliciviruses Lagovirus europaeus GI.1 (previously called rabbit hemorrhagic disease virus-RHDV) and Lagovirus europaeus GI.2 (previously called RHDV2 or RHDVb) [1, 3, 4] . This disease was first reported in China in 1984, and has, since, spread rapidly around the world in less than 10 years, causing considerable economic losses in the rabbit industry and impacting the ecology of wild rabbit populations [1, 2, 5, 6] . In 1989, OIE designated this illness as a viral hemorrhagic disease and added it to List B of the International Animal Health Code [7] . Subsequently, a novel lagovirus, GI.2, emerged in France in 2010 [4] . GI.2 is now endemic in Europe and Australia, and appears to be replacing GI.1 strains in these regions [8] [9] [10] . RHDV (rabbit hemorrhagic disease virus) is the etiologic factor of RHD. RHDV is a calicivirus in the genus Lagovirus, family Caliciviridae [1] . RHDV is a non-enveloped icosahedral virus possessing a single-stranded positive sense RNA genome that is approximately 7.4 kb in length [2, 11] . The genome comprises a 5 untranslated region (UTR), a 3 UTR, and two overlapping open reading frames (ORFs): ORF1 and ORF2. ORF1 encodes a polyprotein that is cleaved by the viral protease into seven nonstructural proteins (NSP1-7) and a major structural capsid protein VP60 (presently VP1) at its C-terminus. VP10 (presently VP2) is a minor structural protein that is encoded by ORF2 [11] [12] [13] .