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  • Author or Editor: Prem S. Paul x
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SUMMARY

Cellular and humoral immune responses of pigs inoculated with Mycoplasma hyopneumoniae were investigated at postinoculation weeks (piw) 2, 4, and 6. The response of blood lymphocytes (bl) and bronchial lymph node lymphocytes (lnl) to stimulation by M hyopneumoniae antigens was evaluated by a lymphocyte-stimulation test. Specific antibodies in serum and lung washing samples were assayed by elisa. Immunoglobulin-positive cells in lungs and bronchial lymph nodes were identified by indirect fluorescent antibody test, using isotype-specific monoclonal antibodies.

At piw 0 to 6, bl from control and M hyopneumoniae-inoculated pigs were stimulated by M hyopneumoniae cells; however, bl from inoculated pigs generally had higher stimulation indices, especially at piw 6. The response of lnl was influenced by previous exposure to M hyopneumoniae, as indicated by higher stimulation indices (P < 0.01) of lnl from inoculated pigs killed at piw 2 and 6. Specific elisa antibodies to M hyopneumoniae in lung washings from inoculated pigs consisted mainly of IgG and IgA isotypes.

Examination of lung sections by indirect immunofluorescence revealed that cells producing IgM and IgA were in controls as well as M hyopneumoniae-inoculated pigs, but IgG-positive cells were only in lungs of inoculated pigs. Resolution of pneumonia appeared to correlate with development of increased sensitization of bl, as well as development of marked increases in immunoglobulins, particularly IgG in lung washings at piw 6.

Free access
in American Journal of Veterinary Research

The following article, “Virus-induced maternal reproductive failure of swine,” was prepared by Dr. Mengeling and his colleagues in response to our request that he provide a concise overview of some of what is presently known about this subject, especially in regard to events of the past 10 years. A lot has happened during this interval. For example, about a decade ago, the JAVMA published a report titled, “Farm studies of porcine parvovirus injection” (JAVMA, Mar15, 1983, pp 592–594). On the basis of this and other information available at the time, it was clear that porcine parvovirus (ppv) was an important reproductive pathogen for swine; however, the development of a vaccine for ppv-induced reproductive failure just a few years before suggested that the clinical impact of ppv soon would be minimized. It appears that this expectation has been realized, at least in part. What was not, and could not be, predicted, however, was that a new virus with devastating effects on swine reproduction would suddenly appear to counterbalance some of the gains made in the control of ppv. The new virus, now called porcine reproductive and respiratory syndrome virus, is currently prevalent throughout the major swine-producing areas of this country. In their article, Drs. Mengeling, Paul, and Lager focus mainly on the viruses, including porcine reproductive and respiratory syndrome virus, that are most often associated with maternal reproductive failure in swine in the United States, with special emphasis on information regarding control and diagnosis that would be of value to veterinarians in clinical practice.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Hybridomas secreting monoclonal antibodies (mab) to transmissible gastroenteritis virus (tgev) were produced by fusion of SP2/0 myeloma cells and splenic lymphocytes of BALB/c mice immunized with the virulent cell-passaged Miller strain of tgev. The mab secreted by these hybridomas were partially characterized; 4 of them (MA4, MA5, MH11, MB2) had high-neutralization titer for tgev. The remaining 7 (MC6, MD9, ME5, MG5, MF2, ME9, MG7) did not neutralize tgev at 1:25 dilution. All 4 neutralizing and 2 of the nonneutralizing mab reacted with the E2 protein of tgev in a radioimmunoprecipitation assay. The remaining 5 mab reacted with the E1 protein of tgev. Reactivity of the mab was tested in an indirect immunofluorescent assay with 3 cell culture-adapted strains of tgev (Miller, Purdue, and Illinois) and 13 wild-type isolates of tgev. Neutralizing mab reacted with all 13 wild-type isolates and the 3 cell culture-adapted strains of tgev. In contrast, nonneutralizing mab that reacted with the Miller strain of TGEV varied in their reactivity with the wild-type tgev isolates. Reactivity of neutralizing mab was also tested, using plaque-reduction neutralization assays with Miller, Purdue, and Illinois strains and 5 wild-type isolates. All 4 neutralizing mab neutralized the 8 virus isolates, but the neutralization titer was higher with the homologous virus than with the heterologous virus isolates. However, neutralization titers of the 4 neutralizing mab were 4 to 16 times higher for the homologous Miller strain of tgev than for the heterologous Illinois and Purdue strains, and were 4 to 1,000 times higher than for the wild-type isolates. Extensive antigenic heterogeneity was observed among tgev isolates on epitopes recognized by the nonneutralizing mab directed against either E1 or E2 protein.

Free access
in American Journal of Veterinary Research

Summary

Viral rna oligonucleotide fingerprinting was used to discriminate 3 cytopathic vaccine bovine viral diarrhea viruses (bvdv) grown in medium supplemented with serum contaminated with noncytopathic bvdv from the same 3 viruses grown in cell culture free of bvdv. Oligonucleotide fingerprinting also effectively discriminated between reference Singer bvdv, nadl bvdv, and New York-1 bvdv grown in bvdv-free noncontaminated or bvdv-contaminated cell cultures. Oligonucleotide fingerprint mapping of viral rna maybe used to determine the purity of virus stocks, as well as that of bvdv vaccines.

Free access
in American Journal of Veterinary Research

SUMMARY

Viral rna oligonucleotide fingerprinting was used to compare genetic relationships among pestiviruses originating from ovine or bovine host species. Ovine pestiviruses, including reference border disease virus and 2 border disease isolates originating from natural pestivirus infections of sheep, appeared to have a more distant genetic relationship among themselves than with certain bovine pestiviruses. A closer genetic relatedness was evident between border disease virus and 3 noncytopathic bovine pestiviruses, including Draper bovine viral diarrhea virus (bvdv), a bvdv isolate that originated from aborted bovine fetuses, and a virus that was isolated from the serum of a calf that had a chronic bvdv infection. Four noncytopathic bovine viruses, including Draper bvdv and 3 field isolates, were closely related. Reference Oregon C24V bvdv, a cytopathic virus, was closely related to only 1 of the 7 noncytopathic viruses in this study.

Free access
in American Journal of Veterinary Research