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Bulletin No. 16 - Fall 2003
Fourth International Symposium on Emerging and Re-emerging Pig diseasesSwine Influenza
CANDOTTI P, FONI E, LEOTTI G, JOISEL F, LONGO S, ROTA NODARI S
Serological prevalence for swine influenza virus in pigs between 3 and 15 weeks of age in Italian farms: evaluation of a maternal antibody decay curve.
Proceedings of the 4th International Symposium on Emerging and Re-emerging Pig Diseases, 2003, 272-273
In order to avoid any interference due to maternally derived antibodies, it is necessary to determine the most appropriate time for Flu vaccination. To this end, a maternal antibody decay curve was evaluated for influenza virus subtypes H1N1, H3N2 and H1N2 in 1000 piglets from 21 farrow-to-weaning or farrow-to-finish Italian herds, from 3 weeks to 15 weeks of life. Due to the low prevalence of the H1N2 subtype, a curve was difficult to evaluate. As far as H1N1 and H3N2 are concerned, the obtained curves showed a linear decline. The hemagglutination inhibition (HI) antibody titers under 1:40, i.e. the minimum to obtain protection after challenge with the virulent H1N1 subtype, were extrapolated from the curves and corrisponded to 15 and 23 weeks respectively for H1N1 and H3N2 subtypes. The groups of 3 and 6 weeks of age showed a significantly higher seroprevalence for subtypes H1N1 and H3N2 in relation to the other age groups, indicating that most piglets over 6 weeks of age do not have maternal antibodies anymore.
