Enhancement of protective immune responses by oral vaccination with Saccharomyces cerevisiae expressing recombinant Actinobacillus pleuropneumoniae ApxIA or ApxIIA in mice.
We previously induced protective immune response by oral immunization with yeast expressing the ApxIIA antigen. The ApxI antigen is also an important factor in the protection against Actinobacillus pleuropneumoniae serotype 5 infection; therefore, the protective immunity in mice following oral immunization with Saccharomyces cerevisiae expressing either ApxIA (group C) or ApxIIA (group D) alone or both (group E) was compared with that in two control groups (group A and B). The immunogenicity of the rApxIA antigen derived from the yeast was confirmed by a high survival rate and an ApxIA-specific IgG antibody response (p < 0.01). The highest systemic (IgG) and local (IgA) humoral immune responses to ApxIA and ApxIIA were detected in group E after the third immunization (p < 0.05). The levels of IL-1beta and IL-6 after challenge with an A. pleuropneumoniae field isolate did not change significantly in the vaccinated groups. The level of TNF-alpha increased in a time-dependent manner in group E but was not significantly different after the challenge. After the challenge, the mice in group E had a significantly lower infectious burden and a higher level of protection than the mice in the other groups (p < 0.05). The survival rate in each group was closely correlated to the immune response and histopathological observations in the lung following the challenge. These results suggested that immunity to the ApxIA antigen is required for optimal protection.
Shin
Sung Jae
SJ
Department of Infectious Diseases, College of Veterinary Medicine, BK21 for Veterinary Science and KRF Zoonotic Disease Priority Research Institute, Seoul National University, Seoul 151-742, Korea.
Shin
Seung Won
SW
Kang
Mi Lan
ML
Lee
Deog Yong
DY
Yang
Moon-Sik
MS
Jang
Yong-Suk
YS
Yoo
Han Sang
HS
D000189:Actinobacillus Infections / Q000517:prevention & control; D016977:Actinobacillus pleuropneumoniae / Q000235:genetics / Q000276:immunology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001426:Bacterial Proteins / Q000032:analysis / Q000276:immunology*; D016207:Cytokines / Q000032:analysis / Q000097:blood; D004195:Disease Models, Animal; D005260:Female; D006460:Hemolysin Proteins / Q000032:analysis / Q000276:immunology*; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology; D007422:Intestines / Q000276:immunology; D008168:Lung / Q000166:cytology / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D011994:Recombinant Proteins / Q000276:immunology*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000276:immunology; D016019:Survival Analysis; D013997:Time Factors; D014611:Vaccination; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology*
D000907:Antibodies, Bacterial; C085361:ApxII toxin, bacteria; D001426:Bacterial Proteins; D016207:Cytokines; D006460:Hemolysin Proteins; D007070:Immunoglobulin A; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; C087744:ApxI toxin, Bacteria