Autogenous Streptococcus suis serotype 1 bacterin: immunogenicities of sow and gilt vaccination protocols.

BACKGROUND

Diseases caused by () infection have a major impact on return on investment, use of antibiotics and animal welfare in piglet rearing worldwide. bacterins are commonly used as autogenous vaccines in different countries but experimental studies indicate limitations of bacterins in protective efficacy. In this study we read out levels of IgG, IgM and IgA binding to a serotype () 1 outbreak strain and bactericidal immunity after application of a homologous bacterin to sows and gilts. In the first trial we recorded immunogenicities after preparturient sow vaccination. In the second trial we compared an intranasal versus an intramuscular second boost application in gilts, and in the third trial the impact of the second boost application prior farrowing of gilts was specifically investigated.

RESULTS

Preparturient intramuscular application of a 1 (, , ) autogenous bacterin elicited significantly increased levels of serum IgG but not IgM binding to the surface of the homologous strain. Accordingly, specific serum IgG levels were significantly increased in the second and fourth week of life in piglets of these sows. Increased IgG levels were associated with decreased proliferation of 1 in blood of 2-week-old piglets reared by vaccinated sows. The increase of IgM binding to 1 between the fourth and sixth week of life was comparable between piglets farrowed by vaccinated and non-vaccinated sows. Levels of serum IgA binding to 1 were not different between piglets fostered by vaccinated and non-vaccinated sows. Between the fourth and sixth week of life we recorded a significant increase in specific serum IgA levels. Intramuscular prime boost vaccination of gilts during quarantine elicited significantly increased specific serum IgG but not IgA levels. Levels of IgG in colostrum binding to 1 were significantly increased only in gilts boostered intramuscularly 3 weeks pre farrowing and not in gilts boostered intranasally. Neither intramuscular nor intranasal boostering was associated with increased levels of specific IgA in colostrum. The significant influence of the second intramuscular boost vaccination pre farrowing in gilts on IgG levels in colostrum and in blood of 2-week-old-piglets was confirmed in the last trial.

CONCLUSIONS

Intramuscular prime-boost vaccination of sows and gilts with an autogenous 1 bacterin is associated with significantly increased levels of specific IgG in their colostrum and serum of 2- and 4-week-old piglets based on the investigations in one herd that had experienced a severe 1 outbreak. After prime-boost vaccination during quarantine gilts should be boostered again pre-farrowing to ensure increased IgG levels in their piglets. A way to elicit increased specific IgA levels in colostrum, milk or serum through intramuscular or intranasal bacterin application was not identified.