Immunogenicity of an inactivated Chinese bovine viral diarrhea virus 1a (BVDV 1a) vaccine cross protects from BVDV 1b infection in young calves.

Bovine viral diarrhea virus (BVDV) 1a and 1b strains are the predominant subgenotypes in China. Because of the genetic and antigenic variability among different BVDV strains, a vaccine effective in one region may fail to protect against infections caused by different virus strains in another region. No BVDV vaccine developed with the predominant strains in China are available. In this study, the immunogenicity of an inactivated Chinese BVDV 1a NM01 vaccine strain was evaluated by challenging with a Chinese BVDV 1b JL strain. Ten 2-4-month-old calves were intramuscularly vaccinated with a single dose of the vaccine strain and boosted with same dose three weeks after the first vaccination, with five mock immunized calves serving as a control group. The average titer of neutralization antibody to BVDV 1a and BVDV 1b of immunized calves reached 1:410 and 1:96, respectively, at 21 days post the second vaccination. Twenty-one days post the second vaccination, all calves were challenged with strain JL. The clinical signs, such as the temperature and leukopenia of the immunized calves and viral shedding, were significantly less than the mock immunized calves after challenging with the virulent BVDV 1b strain, indicating that the BVDV 1a vaccine strain elicited efficacious protection against the endemic BVDV 1b strain in China. To the best of our knowledge, this is the first report of an inactivated BVDV vaccine which demonstrated effective cross-protection against BVDV type 1b infection in China.

Genetic characterization of a noncytopathic bovine viral diarrhea virus 2b isolated from cattle in China.

In January 2013, several clinical signs of cattle with diarrhea, cough, nasal discharge, and fever were reported in Jilin province, China. One virus named SD1301 was isolated and identified. Complete genome of the virus is 12258nt in length and contains a 5'UTR, one open reading frame encoding a polyprotein of 3,897 amino acids and a 3'UTR. Phylogenetic analysis of 5'UTR, N(pro), E1 and E2 gene demonstrated the virus belonged to BVDV 2b, and genetically related to the BVDV strain Hokudai-Lab/09 from Japan in 2010. This bovine viral diarrhea virus displays a unique genetic signature with 27-nucleotide deletion in the 5'UTR, which is similar to the bovine viral diarrhea virus C413 (AF002227). This was the first confirmed isolation of ncp BVDV2b circulating in bovine herd of China.

A bovine viral diarrhea virus type 1a strain in China: isolation, identification, and experimental infection in calves.

BACKGROUND: Bovine viral diarrhea virus (BVDV) is one of the most important pathogens in cattle. Previously, BVDV sub-genotypes of 1b, 1c, 1d, and 1 m were detected in China. However, isolation of BVDV type 1a from cattle has not been reported in China. In 2010, twenty nasal swabs and blood samples were collected from the cattle suspected BVDV infection in Henan province, China. A BVDV isolate was isolated using cell culture, and the pathogenesis of the virus isolate was studied. METHODS: Virus isolation was performed on MDBK cells. The virus identification was conducted by RT-PCR, neutralization test and immunofluorescence assay. In order to determine the genotype of the newly isolated virus, the 5' un-translated region (5'UTR) of the virus isolate was cloned, sequenced and phylogenetically analyzed. To evaluate the virulence of the virus isolate, four BVDV sero-negative calves were intranasally inoculated with the virus suspension. Rectal temperatures and clinical signs were recorded daily. Blood samples were analyzed for changes in white blood cell counts, and tissue samples were taken for histopathology analysis. RESULTS: A new isolate of bovine viral diarrhea virus (BVDV), named HN01, was isolated from the nasal swabs using MDBK cell culture. The HN01 strain caused cytopathic effect (CPE) in MDBK cell cultures after two passages. The virus specifically reacted to BVDV1-specific monoclonal antibody in an immunofluorescence assay. A fragment of 288 bp of genome from this isolate was amplified by the RT-PCR. Phylogenetic analysis of 5'UTR indicated that the virus was BVDV 1a. In the pathogenesis study, four calves experimentally infected with the BVDV strain developed depression, cough and other clinical signs. Calves showed high temperature over 40°C, and white blood cell counts dropped more than 40%. CONCLUSIONS: A new subgenotype 1a strain of BVDV was firstly isolated from dairy cattle in China. The experimental infection showed that the virus was moderate pathogenic to cattle and can be used as a BVDV challenge virus to evaluate the efficacy of BVDV vaccines in the target animals.

Detection of mink enteritis virus by loop-mediated isothermal amplification (LAMP).

Loop-mediated isothermal amplification (LAMP) method was discovered in the last decade but only used for the first time in the diagnosis of mink enteritis virus (MEV) infection in this study. The amplification could be completed within 60 min, under isothermal condition at 65°C, by employing a set of four primers targeting the VP2 gene of MEV. The LAMP was more sensitive than the conventional PCR, with a detection limit of 10(-1) median tissue culture infective doses (TCID(50))/ml per reaction, compared with 10 TCID(50)/ml for PCR analysis. No cross reactivity was observed for other related viruses, including canine distemper virus (CDV) and Aleutian mink disease parvovirus (AMDV). Eighty four of 230 clinical samples were found to be positive for MEV, which is higher than that determined by using the conventional PCR method (68). The results indicate the LAMP can be potentially used to determine MEV as a simple, rapid procedure. This assay would be an available alternative to PCR analysis for the diagnosis of MEV infection in mink, particularly in less well-equipped laboratories and in rural settings where resources are limited.

Phylogenetic analysis of the bovine parainfluenza virus type 3 from cattle herds revealing the existence of a genotype A strain in China.

In 2009, a bovine parainfluenza virus (BPIV3), named as NM09, was isolated using MDBK cell culture from the nasal swabs of normal cattle in China. The NM09 isolate was characterized by RT-PCR and nucleotide sequence analysis. Its complete genome was 15,456 nucleotides in length. Similar to other sequenced PIV strains, the NM09 virus consisted of six non-overlapping genes, which were predicted to encode nine proteins with conserved and complementary 3' leader and 5' trailer regions, conserved gene starts, gene stops, and trinucleotide intergenic sequences. Nucleotide phylogenetic analysis of matrix and hemagglutinin-neuraminidase gene demonstrated that this NM09 isolate belonged to BPIV3 genotype A instead of the previously reported BPIV3 genotype C in China. It is implicated that the different genotypes A and C might coexist infection for a long time in China.

Pathogenesis and phylogenetic analyses of canine distemper virus strain ZJ7 isolate from domestic dogs in China.

A new isolate of canine distemper virus (CDV), named ZJ7, was isolated from lung tissues of a dog suspected with CDV infection using MDCK cells. The ZJ7 isolate induced cytopathogenic effects of syncytia in MDCK cell after six passages. In order to evaluate pathogenesis of ZJ7 strain, three CDV sero-negative dogs were intranasally inoculated with its virus suspension. All infected dogs developed clinical signs of severe bloody diarrhea, conjunctivitis, ocular discharge, nasal discharge and coughing, fever and weight loss at 21 dpi, whereas the mock group infected with DMEM were normal. The results demonstrated that CDV-ZJ7 strain isolated by MDCK cell was virulent, and the nucleotide and amino acid sequences of strain ZJ7 had no change after isolation by MDCK cell when compared with the original virus from the fresh tissues. Molecular and phylogenetic analyses for the nucleocapsid (N), phosphoprotein (P) and receptor binding haemagglutinin (H) gene of the ZJ7 isolate clearly showed it is joins to the Asia 1 group cluster of CDV strains, the predominant genotype in China.