ABSTRACT
Thirty-three pestiviruses isolated from bovines on different farms in Chile were characterized at the molecular level. The 5'-untranslated region (5'UTR) of the isolates was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and subsequently digested with restriction enzymes (RE) Bgl I, Xho I and Pst I. Furthermore, the isolates were amplified by differential RT-PCR, which selectively amplified bovine viral diarrhea virus type 2 (BVDV-2) but not bovine viral diarrhea virus type 1 (BVDV-1). Of the 33 isolates, 16 were classified as BVDV-1 and 17 as BVDV-2. Phylogenetic analysis of the PCR-amplified fragments from 14 isolates showed the presence of viruses belonging to the BVDV-1a, BVDV-1b, BVDV-1c, and BVDV-2 types. Antigenicity of some viruses belonging to both genotypes was studied by cross-seroneutralization, revealing great antigenic differences among them. It is concluded that BVDV viruses circulating in Chile are genetically and antigenically heterogeneous, comprising isolates of genogroups 1 and 2.
Subject(s)
Bovine Virus Diarrhea-Mucosal Disease/microbiology , Diarrhea Virus 1, Bovine Viral/classification , Diarrhea Virus 1, Bovine Viral/isolation & purification , Diarrhea Virus 2, Bovine Viral/classification , Diarrhea Virus 2, Bovine Viral/isolation & purification , Phylogeny , Animals , Base Sequence , Bovine Virus Diarrhea-Mucosal Disease/epidemiology , Cattle , Chile/epidemiology , Diarrhea Virus 1, Bovine Viral/genetics , Diarrhea Virus 2, Bovine Viral/genetics , Gene Amplification , Genotype , Molecular Sequence Data , Restriction Mapping , Reverse Transcriptase Polymerase Chain Reaction/veterinary , Sequence Alignment/veterinaryABSTRACT
Our objective in this cross-sectional study was to determine the seroprevalence in 1996 of commercial dairy herds in central Chile positive to bovine viral diarrhea (BVD) virus, by the detection of antibodies in bulk-tank milk samples. Samples were obtained from 501 dairy farms ( approximately 50,000 cows) from the Metropolitan, VI, VII and VIII regions of Chile. An indirect ELISA was used to detect BVD antibodies. An absorbance (A450) > or = 0.55 was considered positive. The apparent proportion of positive herds ranged from 71.2 to 83% by region and did not differ by region. We concluded that exposure to BVD was widely distributed in the central area of Chile in 1996.