Investigation of viral copy number of bovine viral diarrhea virus in serum of persistently infected calves with colostral antibodies
2019
Miyane, K. (Hokkaido Kamikawa Livestock Hygiene Service Center, Asahikawa (Japan)) | Matsuda, K. | Hiraki, R. | Fujimoto, A. | Kanno, T.
This study aimed to determine whether serum is suitable for reverse transcription polymerase chain reaction (RT-PCR) detection of persistent infection (PI) of bovine viral diarrhea virus (BVDV) in calves that have maternal colostral antibodies. In addition, evaluation of availability of pooled serum for use as a screening method for the detection of cows with PI was also examined. To investigate these aims, we developed a quantitative, real-time RT-PCR for the detection of BVDV. Quantitative studies showed that the minimum value in PI calves that have colostral antibodies was 2.17 × 10E4 copies, which was higher than the detection limit for RT-PCR (approximately 6.25 ×10E3 copies) ; however, the copy number in the serum was significantly low and the antibody titer was high. This suggests a transient decrease in the copy number due to colostral antibodies. The RT-PCR of pseudo-pooled serum using PI sera and fetal bovine serum showed obscure detection of the specific target band in diluted samples from low-copied PI serum. Our study indicated that calf serum with colostral antibodies would be a useful diagnostic material for the RT-PCR detection of PI with BVDV ; however, pooled serum might be affected by a transient decrease in BVDV copy numbers due to colostral antibodies.
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