Introduction

In modern swine production sows are vaccinated against several diseases, either to protect the sows or to protect the sows’ progeny (or both). This leads to the fact that sow vaccination schemes can become very extended and very complex. To be able to work more practical and to reduce the number of injections for the sows, farmers are eager to look for options to combine vaccines without compromising on the efficacy.

Porcilis AR-T DF (1) and Porcilis Porcoli DF (2) are two vaccines that are given to pregnant sows to pass on passive immunity through MDA to their offspring to protect them against atrophic rhinitis and neonatal E. coli diarrhoea, respectively. Porcilis AR-T DF contains a sub-unit of the P. multocida toxin (PMT) in combination with B. bronchiseptica (Bb) cells and Porcilis Porcoli DF contains purified fimbrial adhesins (F4ab, F4ac, F5 and F6) and the E. coli heat labile toxin (LT). Since both vaccines require the same vaccination schedule (basic vaccination eight-six weeks and booster/re-vaccination four-two weeks before farrowing) and both vaccine use Diluvac Forte (d,l-α-tocopheryl acetate) as the adjuvant, it was tested in the present study if injection of the vaccines after mixing would influence the antibody responses against the individual vaccine antigens.

Materials and Methods

Three groups of 10 pigs of eight months of age with no or low antibody titres against the vaccine antigens were injected twice intramuscularly with a four-week interval with Porcilis AR-T DF (2ml), Porcilis Porcoli DF (2ml) or both products after mixing (4ml). Two weeks after the second vaccination, serum samples were taken. Antibody titres were determined in a toxin-neutralisation assay (PMT), a micro-agglutination test (Bb) or by ELISA (E. coli antigens).

Results and Discussion

The serological responses after vaccination with the two vaccines given individually or mixed are presented in Table 1.

For each antigen, groups with different superscripts are significantly different (p<0.05, two-sample t-test).

For nearly all antigens, there was no significant difference between the antibody titre induced by the single vaccines or by the mixed products.

However, for the F5 and LT antigens, the antibody levels induced after mixing of the two vaccines were significantly lower than those induced by Porcilis Porcoli DF alone. In both the single and the combined group, uniform titre values were reached after vaccination, which allowed for detecting significant difference between for the F5 and the LT titre values, however the serum antibody levels against these two antigens after mixed vaccination were still above the level that can be considered to provide protection via the colostrum (2).

References

1. Riising, H-J, P. van Empel & M. Witvliet (2002) Vet. Rec. 150, 569-571
2. Riising, H-J, M. Murmans & M. Witvliet (2005) J. Vet. Med. B 52, 296-300

This paper was presented at the 21st International Pig Veterinary Society (IPVS) Congress 2010 on 19-21 July 2010 in Vancouver, Canada.
For more information about the Congress, click here.

Further Reading

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Find out more information on the diseases mentioned in this article by clicking here.

July 2010