Field Application of the Combination of Neutralizing Test and Virus Isolation, Socalled Spot Test, to Detect Herds Including Cattle Persistently Infected with Bovine Viral Diarrhea Virus

Abstract

ABSTRACT. To detect herds including cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV), application of the combination of neutralizing antibody detection and virus isolation, so-called spot test, were performed on sera of 3 calves selected from each of 26 farms. Nine farms were judged as positive because 64 or more antibody titers were detected from 2 or more calves or BVDV was isolated from one or more calves. PI cattle were detected from 8 of the 9 farms. The positive judgment on one farm was obtained only when the indicator virus used on the neutralizing test was genotypically identical with the isolate from the farm. These results suggest that the spot test can be effective in detecting herds with PI cattle and that the accuracy may be influenced by the genotypes of the indicator viruses. KEY WORDS: bovine viral diarrhea virus, persistently infected cattle, spot test.

Specificity and sensitivity of an indirect fluorescent antibody test to detect antibodies against bovine viral diarrhea virus

“…21,27 However, accurate VN titers may not be obtained owing to the antigenic variation among BVDV strains if the genotype or subgenotype of the challenge viruses used in the VN test differ from the BVDVs that have recently invaded or are circulating in the target cattle herds; in this situation, false-negative results may occur. 21,28 Therefore, correctly selecting the challenge viruses used in the VN tests is critical. In one study, 28 using several genotypes was recommended, including those mainly circulating within the country where the test is being performed, as challenge viruses in the VN test to avoid herd misclassification resulting from antibody titer levels.…”

“…21,28 Therefore, correctly selecting the challenge viruses used in the VN tests is critical. In one study, 28 using several genotypes was recommended, including those mainly circulating within the country where the test is being performed, as challenge viruses in the VN test to avoid herd misclassification resulting from antibody titer levels. It is usually not easy to define the genotypes and subgenotypes to which cattle herds were exposed before examination.…”

“…7,21,27 However, the selection of the challenge virus used in the VN test is critical because of the antigenic variation between BVDV1 and BVDV2 or among different subgenotypes. 21,28 Therefore, if the antigenicity of the challenge virus used in the VN test is fundamentally different from the virus circulating in the herd under test, false-negative results may be obtained. 21,28 We re-evaluated whether the IFA test, which we modified from earlier studies, 8,12,13,15,23 is a suitable serologic test to detect BVDV antibodies, and then compared our test with the VN test and an ELISA.…”

“…7,21,27 However, the selection of the challenge virus used in the VN test is critical because of the antigenic variation between BVDV1 and BVDV2 or among different subgenotypes. 21,28 Therefore, if the antigenicity of the challenge virus used in the VN test is fundamentally different from the virus circulating in the herd under test, false-negative results may be obtained. 21,28…”

Application of Restriction Fragment Length Polymorphism Analysis to Simple and Rapid Genotyping of Bovine Viral Diarrhea Virus Strains Isolated in Japan

“…The test is most exactly performed when the used indicator virus is antigenically similar to the strain prevalent in the population to be evaluated [17,20]. And the antigenicities are closely related to the genotypes [8,16].…”