Sl. Lathrop et al., Antibody titers against bovine coronavirus and shedding of the virus via the respiratory tract in feedlot cattle, AM J VET RE, 61(9), 2000, pp. 1057-1061
Objective-To describe patterns of seroconversion to bovine coronavirus (BCV
) and shedding of BCV from the respiratory tract in feedlot cattle.
Animals-1,074 calves in feedlots in Ohio, Texas, and Nebraska.
Procedure-Nasal swab specimens were obtained at time of arrival (day 0) and
at various times during the initial 28 days after arrival at feedlots. Spe
cimens were tested for BCV, using an antigen-capture ELISA. Serum samples w
ere obtained at time of arrival and again 28 days after arrival; sera were
analyzed for antibodies to BCV, using an antibody-detection ELISA.
Results-Samples from 12 groups of cattle entering 7 feedlots during a 3-yea
r period revealed that 78 of 1,074 (7.3%) cattle were shedding BCV (range,
0 to 35.9% within specific groups). At time of arrival, 508 of 814 (62.4%)
cattle had low (< 50) or undetectable BCV antibody titers. Seroconversion t
o BCV during the initial 28 days after arrival was detected in 473 of 814 (
58%) cattle tested (range, 20.3 to 84.1% within specific groups). In cattle
shedding BCV from the nasal passages, 49 of 68 (72.1%) seroconverted, and
472 of 746 (63.3%) cattle that were not shedding the virus seroconverted.
Conclusions and Clinical Relevance-Bovine coronavirus can be detected in po
pulations of feedlot cattle in the form of viral shedding as well as seroco
nversion to the virus. Although only a few cattle were shedding the virus a
t the time of arrival at a feedlot, most of the cattle seroconverted to BCV
by 28 days after arrival.