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The assessment of efficacy of porcine reproductive respiratory syndrome virus inactivated vaccine based on the viral quantity and inactivation methods.

Kim H, Kim HK, Jung JH, Choi YJ, Kim J, Um CG, Hyun SB, Shin S, Lee B, Jang G, Kang BK, Moon HJ, Song DS - Virol. J. (2011)

Bottom Line: While viremia did not reduce in the vaccinated groups, the IDEXX-ELISA-specific immunoglobulin G increased more rapidly and to significantly greater levels 7 days after the challenge in all the vaccinated groups compared to the non-vaccinated groups (p < 0.05).The inactivated vaccine failed to show the humoral immunity, but it showed different immune response after the challenge compared to mock group.Although the 106 PFU/mL-vaccinated and BEI-inactivated groups showed significantly greater VN titers 22 days after challenge, all the groups were already negative for viremia.

View Article: PubMed Central - HTML - PubMed

Affiliation: Optifarm Solution Inc., 48 Songnam-ri, Seonggeo-eup, Cheonan, Korea.

ABSTRACT

Background: There have been many efforts to develop efficient vaccines for the control of porcine reproductive and respiratory syndrome virus (PRRSV). Although inactivated PRRSV vaccines are preferred for their safety, they are weak at inducing humoral immune responses and controlling field PRRSV infection, especially when heterologous viruses are involved.

Results: In all groups, the sample to positive (S/P) ratio of IDEXX ELISA and the virus neutralization (VN) titer remained negative until challenge. While viremia did not reduce in the vaccinated groups, the IDEXX-ELISA-specific immunoglobulin G increased more rapidly and to significantly greater levels 7 days after the challenge in all the vaccinated groups compared to the non-vaccinated groups (p < 0.05). VN titer was significantly different in the 106 PFU/mL PRRSV vaccine-inoculated and binary ethylenimine (BEI)-inactivated groups 22 days after challenge (p < 0.05). Consequently, the inactivated vaccines tested in this study provided weak memory responses with sequential challenge without any obvious active immune responses in the vaccinated pigs.

Conclusions: The inactivated vaccine failed to show the humoral immunity, but it showed different immune response after the challenge compared to mock group. Although the 106 PFU/mL-vaccinated and BEI-inactivated groups showed significantly greater VN titers 22 days after challenge, all the groups were already negative for viremia.

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PRRSV-specific antibody titer (ELISA S/P ratio) after challenge. The 4 groups were challenged at day 70 post-primary vaccination. The values shown correspond to the average S/P ratio at each time point.a Mock group was significantly different from other groups (p < 0.05).
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Figure 2: PRRSV-specific antibody titer (ELISA S/P ratio) after challenge. The 4 groups were challenged at day 70 post-primary vaccination. The values shown correspond to the average S/P ratio at each time point.a Mock group was significantly different from other groups (p < 0.05).

Mentions: PRRSV-specific antibodies were found to be absent by ELISA in all the experimental groups before challenge (Figure 1). Until day 4 after challenge, all the groups were serologically negative as determined by IDEXX ELISA (Figure 2). At day 7 after the challenge, all the vaccinated groups became serologically positive. The average S/P ratios of the 104, 105, and 106 PFU/mL PRRSV-vaccinated groups at 7 days were 0.82, 0.72, and 0.67, respectively. The average S/P ratios of the 104 and 105 PFU/mL vaccine-inoculated groups were not significantly different from the 106 PFU/mL vaccine-inoculated groups (p > 0.05). However, all vaccine groups showed significantly different results from the control group only on the seventh day after challenge (p < 0.01). This result indicates that, all vaccinated groups showed faster antibody production than the non-vaccinated group.


The assessment of efficacy of porcine reproductive respiratory syndrome virus inactivated vaccine based on the viral quantity and inactivation methods.

Kim H, Kim HK, Jung JH, Choi YJ, Kim J, Um CG, Hyun SB, Shin S, Lee B, Jang G, Kang BK, Moon HJ, Song DS - Virol. J. (2011)

PRRSV-specific antibody titer (ELISA S/P ratio) after challenge. The 4 groups were challenged at day 70 post-primary vaccination. The values shown correspond to the average S/P ratio at each time point.a Mock group was significantly different from other groups (p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3141684&req=5

Figure 2: PRRSV-specific antibody titer (ELISA S/P ratio) after challenge. The 4 groups were challenged at day 70 post-primary vaccination. The values shown correspond to the average S/P ratio at each time point.a Mock group was significantly different from other groups (p < 0.05).
Mentions: PRRSV-specific antibodies were found to be absent by ELISA in all the experimental groups before challenge (Figure 1). Until day 4 after challenge, all the groups were serologically negative as determined by IDEXX ELISA (Figure 2). At day 7 after the challenge, all the vaccinated groups became serologically positive. The average S/P ratios of the 104, 105, and 106 PFU/mL PRRSV-vaccinated groups at 7 days were 0.82, 0.72, and 0.67, respectively. The average S/P ratios of the 104 and 105 PFU/mL vaccine-inoculated groups were not significantly different from the 106 PFU/mL vaccine-inoculated groups (p > 0.05). However, all vaccine groups showed significantly different results from the control group only on the seventh day after challenge (p < 0.01). This result indicates that, all vaccinated groups showed faster antibody production than the non-vaccinated group.

Bottom Line: While viremia did not reduce in the vaccinated groups, the IDEXX-ELISA-specific immunoglobulin G increased more rapidly and to significantly greater levels 7 days after the challenge in all the vaccinated groups compared to the non-vaccinated groups (p < 0.05).The inactivated vaccine failed to show the humoral immunity, but it showed different immune response after the challenge compared to mock group.Although the 106 PFU/mL-vaccinated and BEI-inactivated groups showed significantly greater VN titers 22 days after challenge, all the groups were already negative for viremia.

View Article: PubMed Central - HTML - PubMed

Affiliation: Optifarm Solution Inc., 48 Songnam-ri, Seonggeo-eup, Cheonan, Korea.

ABSTRACT

Background: There have been many efforts to develop efficient vaccines for the control of porcine reproductive and respiratory syndrome virus (PRRSV). Although inactivated PRRSV vaccines are preferred for their safety, they are weak at inducing humoral immune responses and controlling field PRRSV infection, especially when heterologous viruses are involved.

Results: In all groups, the sample to positive (S/P) ratio of IDEXX ELISA and the virus neutralization (VN) titer remained negative until challenge. While viremia did not reduce in the vaccinated groups, the IDEXX-ELISA-specific immunoglobulin G increased more rapidly and to significantly greater levels 7 days after the challenge in all the vaccinated groups compared to the non-vaccinated groups (p < 0.05). VN titer was significantly different in the 106 PFU/mL PRRSV vaccine-inoculated and binary ethylenimine (BEI)-inactivated groups 22 days after challenge (p < 0.05). Consequently, the inactivated vaccines tested in this study provided weak memory responses with sequential challenge without any obvious active immune responses in the vaccinated pigs.

Conclusions: The inactivated vaccine failed to show the humoral immunity, but it showed different immune response after the challenge compared to mock group. Although the 106 PFU/mL-vaccinated and BEI-inactivated groups showed significantly greater VN titers 22 days after challenge, all the groups were already negative for viremia.

Show MeSH
Related in: MedlinePlus