Immunohistochemical (IHC) testing of skin biopsies (ear notch samples) is a method to identify cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV). Skin biopsies were taken from 90 calves upon arrival (day 0) at a feedlot, and on days 14, 28 and 42 following arrival. Calves were vaccinated with modified live virus (MLV) BVDV vaccine on days 1 and 14 following arrival. Additional samples were taken from 50 of the calves between days 1 and 10 when they were treated for bovine respiratory disease. Immunohistochemical testing for BVDV antigen was performed on all samples. One calf was positive for BVDV antigen by IHC techniques on 5 skin biopsies. This calf was also positive by virus isolation (VI) on the buffy coat of a blood sample taken on day 42 following arrival. All samples from the remaining calves were negative when tested with the IHC method. Other tests, VI and polymerase chain reaction (PCR), used to identify PI cattle may give positive results in cattle recently vaccinated with MLV BVDV vaccine. This study suggests that IHC testing of skin biopsies may be advantageous over other tests to identify PI cattle recently vaccinated with MLV BVDV. Further studies are needed to better define the utility of this testing method for cattle that are PI with BVDV.
DuBois WR, Cooper VL, Duffy JC, et al: Bov Pract 34(2):98-100, 2000