ISOLATION, IDENTIFICATION, MOLECULAR CHARACTERIZATION AND TISSUE CULTURE ADAPTATION OF BOVINE VIRAL DIARRHEA (RELATED VIRUS) RECENTLY ISOLATED IN EGYPT

SALEH, AMANI A.; M.I., ABD EL HAMID; M., IBRAHIM, S.

doi:10.21608/avmj.2024.306010.1319

ISOLATION, IDENTIFICATION, MOLECULAR CHARACTERIZATION AND TISSUE CULTURE ADAPTATION OF BOVINE VIRAL DIARRHEA (RELATED VIRUS) RECENTLY ISOLATED IN EGYPT

Document Type : Research article

Authors

¹ Veterinary Serum and Vaccine Research Institute (VSVRI), Agricultural Research Center (ARC), Cairo, 11381, Egypt.

² Genetic Engineering Research Department, Veterinary Serum and Vaccine Research Institute (VSVRI), Agricultural Research Center (ARC). Cairo, 11381, Egypt.

10.21608/avmj.2024.306010.1319

Abstract

This study reports a wave of abortions, diarrhea and a sharp drop in milk production at a dairy farm. The farm was routinely vaccinated with an imported vaccine against BVDV, containing the typical strains of Pestiviruses (BVDV-1 and BVDV-2). A total of 13 serum samples, 5 vaginal discharge samples, and 5 fecal samples were collected from aborted cows and from cows showing persistent diarrhea. All the samples were screened for potential microbial causes of abortion (viral or bacterial) using PCR. Out of 23 samples tested, only one vaginal discharge sample yielded a positive PCR result at the expected size of 288 bp. The primers used were designed with high sensitivity to 5’-UTR–based-RTPCR assays for the detection of Pestiviruses. The PCR product was sent for sequence analysis, and results were submitted to GenBank Accession Number #OR425033, and designed as GERD/VSVRI/pesti-Giraffe/2022. The virus was then successfully isolated and propagated in MDBK cells through three successive blind passages. A distinct cytopathic effect (CPE) was observed 2–3 days after an incubation period post-virus inoculation, characterized by vacuolation, cell rounding, and cluster formation 72 hours after infection. PCR was carried out on each passage and gave a specific band at the expected size. Further analysis through sequence alignment and phylogenetic analysis revealed that the isolate is closely related to the Pestivirus giraffe, especially Pestivirus PG-2. This marks the first record of detection, isolation, and characterization of this strain in Egypt. Therefore, this epidemic was caused by a newly introduced strain recorded in Egypt. So, the imported vaccines would not provide protection, and the local vaccine need to be updated to include this Pestivirus strains.

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