The decrease in PCV2a and PCV2b genotypes over time and the increase in PCV2d in 2012 may be due more to other, unknown, factors than to immunological selection resulting from PCV2a-based vaccination.
Porcine circovirus (PCV2)
PCV2 vaccination is nearly universal. Has viral presence decreased after 6 years of vaccination? Could vaccination policies be changed?
All available vaccines in the European and North-American market are based on PCV2a genotype, while the most prevalent ones are PCV2b and PCV2d ones. Although significant level of cross-protection among these three genotypes has been demonstrated, it would be interesting to assess if vaccine efficiency would be equivalent in front of all these different genotypes.
This article deals with the factors to be considered for deciding the optimal time of vaccination against PCV2 and shows the results of a study that evaluates the efficacy of different vaccination programs in PCV2 subclinically infected piglets.
Recently, PCV2 has been suggested as a pathogen able to induce diarrhoea in pigs, and PCV2-enteric disease (PCV2-ED) as a separate entity within porcine circovirus diseases (PCVDs) has been proposed.
The loss associated with decreased ADWG was of 13.1 € and 7.5 €/pig at 21 weeks of age for pigs with high and medium serum PCV2 load under the scenario studied.
Distinct PCV2 variants are circulating in commercial pig farms. How the vaccine induced immunity may affect PCV2 evolution?