• 대한수의학회지
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• 제56권3호
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• pp.167-176
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• 2016

We investigated whether maternal antibodies (mAbs) elicited by dams immunized with recombinant vaccine candidates against avian pathogenic Escherichia coli (APEC) can passively confer protective immunity to chicks. In the present study, pBP244 plasmids carrying selected antigens of APEC were transformed into Salmonella Typhimurium JOL912, which was used as a vaccine candidate against APEC. The hens were immunized with the vaccine candidates using prime or booster doses. The levels of IgG and sIgA specific to the selected antigens increased significantly following prime immunization. To evaluate the persistence of passively transferred mAbs, the levels of IgY and IgA were determined in egg yolks and whites, respectively. The eggs from the immunized group showed consistently increased levels of IgY and IgA until week 16 post-laying (PL) and week 8 PL, respectively, relative to the control group. The presence of mAbs was observed in chicks that hatched from the hens, and titers of plasma IgY were consistently raised in those from the immunized hens by day 14 post-hatching. Further, chicks from the immunized hens were protected from challenge with a virulent APEC strain, whereas those from non-immunized hens showed acute mortality.

• 대한수의학회지
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• 제53권3호
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• pp.163-167
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• 2013

Avian pathogenic Escherichia coli (APEC) are known to cause extraintestinal disease in poultry, leading to substantial losses in the industry. IutA, iron-regulated aerobactin receptor is firmly associated with APEC. To assess the potential of IutA to induce protective immune responses, attenuated Salmonella Typhimurium strain expressing IutA was constructed and administered orally to BALB/c mice. The IutA-specific immune responses were measured with sera, vaginal and fecal samples by an enzyme-linked immunosorbent assay. We found that the Salmonella-IutA vaccine induced significantly higher immune responses as compared to the control inoculated with the attenuated S. Typhimurium containing the plasmid only. The IutA-specific immune responses were increased by second immunization at third week after initial immunization, whereas triple immunization induced lower immune responses than those induced by the double immunization. The Salmonella-IutA vaccine induced a nature of immunity biased to the Th1-type, as judged by the ratio of IutA-specific IgG isotypes (IgG2a/IgG1). Overall, these results suggest that the Salmonella-IutA vaccine appear to be suitable candidate for a vaccine against APEC.

• 대한수의학회지
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• 제53권4호
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• pp.199-205
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• 2013

Avian pathogenic Escherichia coli (APEC) is a causative agent for a number of extra intestinal diseases and account for significant losses to the poultry industry. Since protective immunity against APEC is largely directed to virulence antigens, we have individually expressed four different viulence antigens, papA, papG, IutA, and CS31A, using an attenuated Salmonella Typhimurium and a plasmid pBB244. Following oral immunization of mice with combination of two or four of these strains, serum IgG and mucosal IgA responses were elicited against each antigen represented in the mixture. The antigen-specific mucosal IgA responses were significantly higher in the group of mice immunized with the heat-labile Escherichia coli enterotoxin B subunit (LTB) strain than those in the group of mice immunized without the LTB strain. While, there was no significant difference between these two groups in antigen-specific serum IgG responses. The results showed that LTB could act as mucosal immune adjuvant. To assess the nature of immunity, the distribution of antigen-specific IgG isotypes was analyzed. All groups promoted Th1-type immunity as determined by the IgG2a/IgG1 ratio. Thus, our findings provided evidence that immunization with a combination of several vaccine strains is one of the strategies of developing effective vaccines against APEC.

• 한국임상수의학회지
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• 제28권3호
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• pp.297-302
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• 2011

조류병원성 대장균 (APEC)은 가금에서 많은 장관외 질병을 야기한다. 병원성 인자 중 하나인 P-fimbriae 또한 질병과 밀접하게 관련되어 있다. 이번 연구에서 마우스에 P-fimbriae의 subunit 들인 PapA와 PapG를 발현하는 재조합 약독화 Salmonella Typhimurium 백신균주 접종 후 APEC 방어에 필요한 면역반응 유도 여부를 알아보기 위한 실험을 수행하였다. 각 백신 균주로 경구 접종 후 각 항원에 대한 serum IgG 항체 역가는 접종 후 4주째부터 대조군에 비해 항체 역가가 높게 유도되기 시작하여 실험이 끝날 때까지 높은 항체 역가가 계속 유지 되었다. 한번 접종 된 경우보다 추가 접종 된 군에서 보다 높은 항체 역가가 관찰되었다. 더불어 각 항원에 대한 mucosal IgA 역가 또한 높게 유도되었다. 두 균주를 혼합하여 접종 하였을 경우에는 각 백신 균주를 접종하였을 경우보다 높은 serum IgG와 mucosal IgA의 역가가 관찰되었다. 이 결과는 이들 백신 균주가 면역원성이 있음을 확인하는 결과였다. 또한 helper T cells type을 알아보기 위해 IgG1과 IgG2a의 항체 역가를 측정하여 본 결과 각 백신 균주를 접종하였을 경우에는 IgG2a의 항체 역가가 IgG1의 항체 역가 보다 월등히 높은 이들 백신 균주를 접종 하였을 경우에는 Th1-type의 면역 반응이 유도되지만 두 백신 균주를 혼합 접종하였을 경우에는 Th1-과 Th2-type 모두를 유도하는 것으로 관찰되었다. 이 결과를 통해서 이들 두 백신 균주를 혼합 접종 하였을 경우에는 세포성 면역뿐만 아니라 체액성 면역 모두를 유도할 수 있음을 확인할 수 있었다.