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  • Author or Editor: Daral J. Jackwood x
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Abstract

Objective

Baculovirus-expressed transmissible gastroenteritis virus (TGEV) spike (S) glycoprotein vaccines were inoculated parenterally in swine to determine whether such vaccines could induce serum and whey virus-neutralizing (VN) antibodies and protective lactogenic immunity for TGEV-challenge-exposed pigs.

Animals and Procedures

3 recombinant baculoviruses that expressed full or partial length TGEV Miller strain S glycoproteins were inoculated SC in 17 conventionally raised 11-day-old TGEV-seronegative pigs to determine whether the recombinant S glycoproteins would elicit serum VN antibodies. Eleven TGEV-seronegative pregnant sows were inoculated SC or intramammarily with subunit vaccines (R2-2 or R3-5) or control proteins. Pigs born to 9 of the 11 sows were challenge exposed at 4 to 5 days of age with the virulent Miller strain, and passive immunity was assessed. Serum and whey antibody responses to TGEV were analyzed by VN and ELISA testing.

Results

Recombinant S glycoproteins (R2-2 or R3-5) containing the 4 major antigenic sites induced similar VN antibody titers to TGEV in serum and colostrum, but low (some sows) or no VN antibody titer was detected in milk. Subcutaneous inoculation of sows with R2-2 or R3-5 elicited IgG, but not IgA antibodies to TGEV in colostrum. Morbidity was 100%, and mortality ranged from 20 to 80% in TGEV challenge-exposed pigs nursing sows inoculated SC or intramammarily with TGEV S glycoprotein vaccines.

Conclusions and Clinical Relevance

Parenterally administered TGEV S glycoprotein vaccines elicit VN antibodies to TGEV in serum and colostrum that do not fully provide active or passive immunity in swine. (Am J Vet Res 1997;58:242–250)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To compare recombinant transmissible gastroenteritis virus (TGEV) spike protein, (SP) R2-2, with attenuated live virus (ALV) vaccine in sows during late pregnancy.

Animals

13 TGEV-seronegative sows and their pigs.

Procedure

At prepartum weeks (PPW) 6 and 4, sows of groups 1 and 2 received ALV via the oral/intranasal (O/IN) route. At PPW 2, group-1 sows received ALV IM and group-2 sows received SPR2-2 IM. Group-3 sows received SPR2-2 IM at PPW 4 and ALV O/IN at PPW 2. Sows of group 4 (negative controls) were inoculated O/IN with mock-infected ST cell fluids at PPW 6 and 4 and IM with Sf9 cell lysates at PPW2 (n = 2), or IM with Sf9 cell lysates at PPW4 and O/IN with mock-infected ST cell fluids at PPW2 (2). Serum, colostrum, and milk samples were tested for antibody to TGEV, and a lymphoproliferative (LP) assay was done on blood mononuclear cells. Suckling pigs were challenge exposed with virulent TGEV.

Results

Sows of groups 1 and 2 had higher IgG and significantly higher antibody titers in colostrum; their pigs had significantly higher serum antibody titer. At challenge exposure of their pigs, LP responses of group-2 sows were significantly higher than those of sows in the other 3 groups. Mean pig mortality ranged from 43 (group 2) to 92% (group 4). Significant negative correlations were observed among litter mortality and sow LP response, colostral titer, and pig serum titer at time of challenge exposure.

Conclusions

In sows vaccinated twice with attenuated live TGEV, the recombinant SPR2-2 administered IM may be comparable to ALV administered IM as a booster. Vaccination failed to provide complete protection to suckling pigs after challenge exposure. (Am J Vet Res 1998;59:1002–1008)

Free access
in American Journal of Veterinary Research

Summary

In vitro transferability of pemcillm. strepiomycin, tetracycline, and erythromycin resistance from coagulase-negative staphylococci to Staphylococcus aureus and among the former species of bovine mammary gland origin was examined by bacterial mating on filters and by mixed-culture matings in broth and in skim milk. One hundred twenty-six (42 each on filter, in broth, and in skim milk) matings were performed among 37 isolates of different Staphylococcus species. Transfer of resistance to penicillin, tetracycline, or erythromycin was not detected. Of 51 matings performed to determine streptomycin-resistance transfer, 9 (3 each on filters, in broth, and skim milk) were successful. Nine strains representing 3 species of coagulase-negative staphylococci were tested as prospective donors of streptomycin resistance. Of these, 2 strains could transfer streptomycin resistance. A double-resistant donor, Shominis, not only transferred its streptomycin resistance to an S chromogenes strain lacking resistance, but also to an S aureus strain already carrying penicillin and tetracycline resistance. The transfer of streptomycin resistance from the donor S hominis, harboring 2 plasmids, to a plasmidless S chromogenes recipient strain was associated with apparent acquisition of the smaller plasmid of the donor by the recipient. The single-resistant donor, S epidermidis 681A, transferred streptomycin resistance to a tetracycline-resistant. S aureus recipient. This strain however failed to transfer its streptomycin resistance to another S aureus, 2 S hyicus, and 1 S xylosus recipient. Frequency of transfer of streptomycin resistance ranged from 1.1 × 10−5 to 1 × 10−4. When transfer of resistance was successful, attempts were made to characterize the transfer process. Conjugation appeared to be the mode of streptomycin-resistance transfer. Transfer of resistance between staphylococci of bovine mammary gland origin appears to be fairly uncommon. However, in view of the limitations of the procedures used, additional in vitro and in vivo work is needed to further assess the role of coagulase-negative staphylococci in dissemination of antibiotic resistance.

Free access
in American Journal of Veterinary Research