Molecular characterization and phylogeny of bovine viral diarrhea virus isolated from persistently infected exotic cattle in Punjab, Pakistan

The study was aimed to determine the status of Bovine viral diarrhea virus (BVDV) in persistently infected (PI) cattle along-with molecular characterization and phylogenetic analysis of viral isolates in Punjab, Pakistan. A total of 600 blood samples (20 from each farm) were taken from local (n=200), crossbred (n=200) and exotic breeds (n=200) of 30 cattle dairies with the history of reproductive problems. Employing Antibody captured ELISA, overall, 41.6% sero-positivity of BVDV evidenced higher sero-positivity (p <0.05) in local breeds (51%) as compared to exotic (41.5%) and cross bred (32.5%) cattle. For the detection of PI animals, only sero-negative samples (n=350) were categorized into 2 groups (A >= 3 years and B <= 3 years) based on age of animals Antigen capture ELISA test was applied on paired samples. During the first round of testing, 4.41% (6/136) samples of group A and 3.27% (7/214) of group B were found positive whereas only 0.46% (1/214, exotic) of group B were declared positive based on 2nd round test result consequently accepted as PI. The results of antigen capture ELISA were also validated by PCR. Sequence analysis of PCR product targeting 5'UTR region of BVDV revealed genotype la in exotic dairy cattle of Punjab having homology with UK and Southern Brazil strains (KF023365, KM007108 and KM007116). The current study results emphasized the need to devise some strategies for implementation of BVDV control measures to increase the productive potential of animals and to curtail its spread to local dairy animals.