Control and eradication methods for bovine viral diarrhea virus.

摘要

The objectives of this research were (1) determine the efficacy of an antigen-capture (AC)-ELISA and micro-titer virus isolation (MTVI)-ELISA in identifying persistently infected (PI) animals from pooled samples; (2) evaluate the economic benefit of pooling samples for PI animal identification; (3) examine the merit of a diagnostic assay able to identify PI animals in utero; and (4) develop an indirect capture ELISA capable of identifying PI animals in utero.; To reduce the cost of whole herd screening, the sensitivity and specificity of an AC-ELISA and MTVI-ELISA using saline from ear notch samples or pooled serum was determined. The sensitivity of pooled ear notch or serum samples using MTVI-ELISA or serum samples using AC-ELISA was too low for use in whole herd screening. Pooling saline from ear notch samples from two animals using AC-ELISA could provide a less expensive method for whole herd screening. A simulation model was used to determine the cost per cow for whole herd screening and time to BVDV eradication using pooled samples. Simulation results indicate the time to eradication could increase by one year when using pools of 2 or 3.; Detection of PI animals in utero could greatly benefit cattle producers. To evaluate the impact of PI animal identification in utero a BVDV transmission model was modified to examine the efficacy of a diagnostic test able to identify PI animals in utero. Simulation results indicate identification of PI animals in utero does not decrease the number of years required to test for PI animals in order to eliminate BVDV from a herd, nor does earlier detection decrease the median number of PI animals born.; An indirect capture ELISA to detect anti-BVDV IgA in the nasal secretions of cows was developed to identify BVDV PI fetuses in utero. To determine if IgA levels in the nasal secretions of cows carrying BVDV PI fetuses were greater than those of cows not carrying PI fetuses, the concentration of anti-BVDV IgA present in nasal secretions was obtained. Nineteen cows had IgA concentrations 2-fold greater than the positive control. Included in those 19, was a cow carrying a PI fetus.