Colostrum-Derived Immunity Reduces Detection of Calves Persistently Infected (PI) with Bovine Viral Diarrhea Virus (BVDV) by Common Diagnostic Tests

Abstract

Diagnosis, detection, and elimination of persistently infected (PI) cattle with bovine viral diarrhea virus (BVDV) is the cornerstone of control programs for BVDV. This study investigated the most reliable tests, sample types, and timing for detecting BVDV in PI calves after colostral consumption. Thirteen pregnant heifers were infected with BVDV1b to produce PI calves. Ten PI calves were born clinically normal. Two age-matched calves were used as a control group. Serum samples, nasal swabs, and ear notches were collected from before colostrum intake to 28 days after birth. Antigen-capture ELISA, RT-qPCR, virus isolation, and the IDEXX SNAP test were performed. Colostrum-derived BVDV1b antibodies suppressed BVDV detection in all sample types during the first week of age, causing false negatives. After 7 days of age, detection of BVDV using ear notch samples with RT-qPCR, ACE, or IDEXX SNAP was highly reliable, while serum-based and virus isolation methods were the least effective.