Immunology Research Of Mink Enteritis Virus Inactivated Vaccine And Prokaryotic Expression Of VP2Partial Gene

Mink viral enteritis a fulminating infectious disease with high mortality caused acute diarrhea and leucopenia, whose pathogens was mink enteritis virus (MEV). It was one of the most disastrous diseases troubled the mink breeding industry, resulting in great financial losses. Unfortunately, there was still no effective therapy for the disease. Therefore, immunization seemed quite important to guard against the virus. Although the minks were vaccinated regularly, unsuccessful inoculation happened every year for the reason that virus kept mutating and evolving. The average nucleotide (nt) substitution rate of mink enteritis virus (MEV) was7.85×10-5per site per year, which was lower than canine parvovirus (CPV) and higher than feline parvovirus (FPV). Mutation of the virus brought great challenge for prevention and treatment. Updating of the vaccine can’t keep up with the pace of the evolution of the virus, so that unsuccessful immunization existed. A mutated strain named MEV-ZYL-1was isolated from Dalian area in2006when mink viral enteritis disease broke out there, and manufactured to be inactivated aluminum-containing vaccine. Healthy minks of50～60day-old from13different farms in Hebin province were inoculated with1mL inactivated vaccine per mink. Serum of totally58immunized minks were collected30days later to measure the level of anti-MEV antibody. Results showed that the lowest level of antibody was25while the highest was211. The inactivated vaccine showed strong protection and was in a positive sense in prevention against the epidemic mink viral enteritis.VP2protein was the most important component element of capsid proteins which accounted for80%, it was determinant in adsorption onto the cells and induction of neutralizing antibody. Nucleotide sequence determining antigenicity and host range of the virus located at VP2genes, changes of certain nucleotide base will affect the biological characteristics of the virus. Commonly, MEV was considered to evolve from FPV when FPV adapt to the new host. Researches showed that mutations between various feline parvovirus sub-species strains isolated from different host took place in the loopl and loop3section. Most of the mutations resulted in replacement of amino acids from the hydrophilic amino acids to hydropobic amino acid or acidic amino acid, especially in the position of300th amino acid in VP2genes. Nucleotide fragment encoding main antigenic site of MEV VP2protein was amplified by analyzing the antigenic index, hydrophilicity plot and surface probability of VP2protein. Recombination protein was expressed using prokaryotic expression system. SDS-PAGE analysis showed that the recombination protein was about50KD and was expressed in the form of inclusion body. The result of western-blotting revealed that the recombination protein can react well with anti-MEV serum. All results indicated that the recombination protein can be valuable in providing good antigen for the anti-MEV monoclonal antibody preparation and related immunological detection method development.