Active and passive immunity in swine vaccinated against leptospirosis. Use of an experimental subunit vaccine and two commercial whole culture bacterins
It was evaluated the performance of a subunit and whole culture bacterin vaccines against leptospirosis in sows by the analysis of agglutinating and neutralizing antibodies level. The intensity and duration of passive immunity in the offspring and active immunity in sows were investigated with microscopic agglutination test (MAT) and leptospira growth inhibition (LGI) in groups of animals treated with experimental subunit vaccine and whole bacterin produced with the same serotype and with two commercial bacterin vaccines. The experiment was performed in two phases. First, 33 sows were divided into three groups of eleven animals each: group 1 was the control and group 2 received two doses with 30 days interval of anti-leptospirosis lipopolysaccharid (LPS) subunit vaccine serovar Canicola and group 3 received two doses with 30 days interval of whole leptospira bacterin. On a second phase 24 sows were divided into three groups of eight animals each: group A received two doses with 30 days interval of the commercial leptospira bacterin A. Group B received two doses with 30 days interval of a commercial leptospira bacterin B and group C was the control. Either in the first phase as in the second one, MAT and LGI were performed in the sows and its piglets in order to evaluate titers of agglutinins and neutralizing antibodies obtained with active and passive immunities respectively. The comparison of agglutinating titers of groups 2 and 3 at the first phase showed differences on days 32 and 68 post vaccination. There was no difference in relation to neutralizing antibodies. Agglutinating antibodies were not detected on thirty days old piglets, born from sows vaccinated with LPS, and for neutralizing antibodies, mean titers were 0.832 on group 2 and 0.930 on group 3. Agglutinating antibodies titers of groups A and B, on the second phase, presented differences between the commercial vaccines serovars at 60, 90 and 120 post vaccination days. At 60 days, there were differences for serovars Copenhageni and Icterohaemorrhagiae. There was persistency of low titers of neutralizing antibodies to serovar Hardjo in the sows, for the seven measurements performed with the two commercial bacterins. It was observed colostral immunity transfer to piglets with three and eight days old only for commercial vaccine B, with detectable agglutinating antibodies. LPS bacteria vaccine presented perspectives to prevent swine leptospirosis. There was difference and low immunological response for commercial vaccines A and B, especially for serovars Canicola, Grippotyphosa, Icterohaemorrhagiae and Pomona; and for serovar Copenhageni only for commercial vaccine B. The passive immunity conferred by commercial vaccines A and B and measured by agglutinating antibodies had low duration.
Advisor:Silvio Arruda Vasconcellos; Raul José da Silva Girio; Fumio Honma Ito; Hélio Langoni; Sonia Regina Pinheiro; Silvio Arruda Vasconcellos
School:Universidade de São Paulo
Source Type:Master's Thesis
Keywords:active immunity animal leptospirosis passive swine vaccines
Date of Publication:12/18/2006