Maternally-Derived Antibodies do not Prevent Transmission of Swine Influenza A Virus Between Pigs

Aug 25, 2016

A transmission experiment involving 5-week-old specific-pathogen-free (SPF) piglets, with (MDA(+)) or without maternally-derived antibodies (MDA(-)), was carried out to evaluate the impact of passive immunity on the transmission of a swine influenza A virus (swIAV). In each group (MDA(+)/MDA(-)), 2 seeders were placed with 4 piglets in direct contact and 5 in indirect contact (3 replicates per group). Serological kinetics (ELISA) and individual viral shedding (RT-PCR) were monitored for 28 days after infection. MDA waning was estimated using a nonlinear mixed-effects model and survival analysis. Differential transmission rates were estimated depending on the piglets' initial serological status and contact structure (direct contact with pen-mates or indirect airborne contact). The time to MDA waning was 71.3 [52.8-92.1] days on average. The airborne transmission rate was 1.41 [0.64-2.63] per day. The compared shedding pattern between groups showed that MDA(+) piglets had mainly a reduced susceptibility to infection compared to MDA(-) piglets. The resulting reproduction number estimated in MDA(+) piglets (5.8 [1.4-18.9]), although 3 times lower than in MDA(-) piglets (14.8 [6.4-27.1]), was significantly higher than 1. Such an efficient and extended spread of swIAV at the population scale in the presence of MDAs could contribute to swIAV persistence on farms, given the fact that the period when transmission is expected to be impacted by the presence of MDAs can last up to 10 weeks.

Source: AASV

Video: CEOs of the Industry: John McIntire, Partner at Pike Pig Systems

CEOs of the Industry, Jim sits down with John McIntire, Partner at Pike Pig Systems, one of the most quietly impressive 26,000-sow operations in the U.S. John shares how he grew from operator to partner, how Pike built a people-first culture with long-tenured managers, and why they’re committed to weaning bigger, stronger pigs at 25+ days.

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If you want a look inside a people-driven, purpose-driven, quietly elite pork system, this is an episode you won’t want to miss.