Porcilis PRRS efficacy against European isolates

Two experiments to show that the vaccination with Porcilis PRRS against an heterologous strain does not entirely prevent infection but offers significant protection against PRRSV challenge.

Experiment A

Method

Pigs vaccinated with Porclis PRRS and unvaccinated pigs (control groups) were challenged with:

• The homologous Lelystad virus strain (98% nucleotide identity in ORF5 with the vaccine strain) OR
• An Italian isolate (84% nucleotide identity in ORF5 with the vaccine strain).

The degree of the reduction of the virus quantities was assessed both in bronco-alveolar lavage (BAL) fluids and in sera (Labarque et al. 2004).

Results

Protection was complete against the challenge with a wild-type strain from the same Lelystad cluster: no infection was registered in the vaccinated pigs.

Graphs 1 and 2. Course of mean PRRSV titres in BAL fluids and sera after challenge with the Lelystad strain in both vaccinated and controls pigs.

Graph 1: Virus titre in BAL fluid (log₁₀)

Graph 2: Virus titre in sera (log₁₀)

The mean virus quantity in the BAL fluids and sera of vaccinated pigs were significantly different from those of non-vaccinated controls.

Graphs 3 and 4. Course of mean PRRSV titres in BAL fluids and sera after challenge with the Italian-like isolate in both vaccinated and controls pigs.

Graph 3: Virus titre in BAL fluid (log₁₀)

Graph 3: Virus titre in sera (log₁₀)

Mean cumulative virus titres in BAL fluids

Mean cumulative virus titres in serum

Conclusion

This experiment demonstrates that the vaccination with Porcilis PRRS against an heterologous strain does not entirely prevent infection but offers significant protection against PRRSV challenge.

Experiment B

Pigs were divided into three groups as follows:

• Group 1: Intramuscular Porcilis PRRS vaccination
• Group 2: Intradermal Porcilis PRRS vaccination
• Group 3: Control group, not vaccinated.

All three groups were challenged with a 2003 isolate of an Italian-like PRRSV strain (78% nucleotide identity in ORF5 with the vaccine strain). The reduction of the viraemia was assessed in sera samples (Cordioli et al. 2004).

Results

Mean challenge virus titres in serum samples

Conclusion

This experiment demonstrates that the vaccination with Porcilis PRRS against an heterologous strain does not entirely prevent infection but offers significant protection against PRRSV challenge.

Top of page