Retrospective serological survey of influenza viruses in backyard pigs from Mexico City.

BACKGROUND: In the present study, we analyzed the presence of antibodies to four different influenza viruses (pH1N1, hH1N1, swH1N1, and swH3N2) in the sera of 2094 backyard pigs from Mexico City. The sera were obtained between 2000 and 2009. OBJECTIVES: The aim of this study was to perform a retrospective analysis of the 2000-2009 period to determine the seroprevalence of antibodies against pH1N1, hH1N1, swH1N1, and swH3N2 viruses in sera obtained from backyard pigs in Mexico City. METHODS: Antibody detection was conducted with hemagglutination inhibition assay (HI) using four influenza viruses. We used linear regression to analyze the tendency of antibody serum titers throughout the aforementioned span. RESULTS: We observed that the antibody titers for the pH1N1, swH1N1, and swH3N2 viruses tended to diminish over the study period, whereas the antibodies to hH1N1 remained at low prevalence for the duration of the years analyzed in this study. A non-significant correlation (P > 0.05) between antibody titers for pH1N1 and swH1N1 viruses was observed (0.04). It contrasts with the significance of the correlation (0.43) observed between the swH1N1 and swH3N2 viruses (P < 0.01). CONCLUSIONS: Our findings showed no cross-antigenicity in the antibody response against the same subtype. Antibodies against pH1N1 virus were observed throughout the 10-year study span, implying that annual strains shared some common features with the pH1N1 virus since 2000, which would then be capable of supporting the ongoing presence of these antibodies.

Muestreo serológico a nivel de rastro para detectar anticuerpos contra el virus de influenza porcina / Detection of antibodies against swine influenza virus in samples of slaughther pigs

Se realizó un muestreo en el rastro de Ferrería ubicado al poniente de la zona metropolitana. A ese lugar llegan animales con un peso de 100 a 105 kilogramos que proceden de los estados de Jalisco, Michoacán, Sonora y Guanajuato, con el fin de que se les explore en busca de anticuerpos contra el virus de la influenza porcina (IP). Se acudió al rastro una vez a la semana, durante dos meses, y se colectó un total de 948 sueros; estos últimos se trabajaron con la técnica de microtitulación de la inhibición de la hemaglutinación (IHA). Se consideró positivos los sueros cuyos títulos fueran mayor o igual a 1:80. Los resultados obtenidos se expresaron en porcentajes de animales positivos y negativos, encontrándose anticuerpos en 601 cerdos (63.40 por ciento) con títulos mayores de 1:10, el resto (347) no presentó anticuerpos. De esta manera 20.25 por ciento presentaron títulos mayores de 1:80 (positivos) contra 70.75 por ciento de títulos menores (negativo)