Tumor necrosis factor alpha (TNF-α) plays an important role in the immune system. In this study, TNF-α expression was analyzed in 11 tissues of 8 piglets resistant to enterotoxigenic Escherichia coli (ETEC) F18 and 8 ETEC F18-susceptible piglets from the Large White breed. The expression levels of TNF-α were high in immune organs (spleen, lung, thymus, and lymph nodes). The levels were higher in ETEC F18-resistant piglets than in ETEC F18-susceptible piglets, with significant differences in spleen, kidney, thymus, lymph node, and duodenum (P < 0.05). The mutation TNF-α −791(C→T) and 3 genotypes (CC, CT, and TT) were identified. The TNF-α expression levels in the spleen, kidney, lymph nodes, and duodenum were significantly higher in the TT pigs than in the CC pigs (P < 0.05). Thus, TNF-α −791(C→T) has significant effects on mRNA expression and may regulate ETEC F18 resistance of weaning piglets. Therefore, the −791(C→T) mutation of the TNF-α gene could be considered an important potential genetic marker of ETEC F18 resistance.

Porcine reproductive and respiratory syndrome virus (PRRSV) can be devastating to commercial breeding operations. The objective of this study was to evaluate a novel European PRRSV vaccinal strain for safety and efficacy in bred gilts. In 2 experiments, 110 gilts were vaccinated intramuscularly and the vaccine was evaluated for safety and efficacy. Gilts in Experiment 1 were evaluated for local and systemic reactions and gilts in both experiments were observed for clinical signs of disease through farrow. In both experiments, piglet clinical observations, piglet average daily weight gain (ADWG), gilt serology [determined by enzyme-linked immunosorbent assay (ELISA)], gilt and piglet viremia [determined by quantitative real-time polymerase chain reaction (qPCR)], as well as piglet lung lesion scores and PRRS virus in lung tissue (qPCR) were determined. The vaccine was shown to be safe as there were no significant differences among groups in either experiment. Efficacy was established in Experiment 2 as both vaccinated groups were associated with desirable significant differences in percentage of gilts with abnormal clinical findings; gilt viral load post-challenge [day 125, day of farrowing (DOF), and DOF + 13]; percentages of alive, healthy live, weak live, and mummified piglets per litter at farrowing and weaning; percentage of piglets per gilt that were positive for viremia; percentage of piglets per gilt with clinical disease; and piglet viral load on DOF. It was concluded that a vaccine formulated from the PRRSV modified live virus (MLV) strain 94881 is a safe and effective method of protection against the detrimental effects of virulent PRRSV infection in breeding female pigs.

The objective of this study was to compare the efficacy of 2 different commercial Mycoplasma hyopneumoniae vaccines and porcine reproductive and respiratory syndrome virus (PRRSV) vaccines in regard to growth performance, microbiological and immunological analyses, and pathological observation from wean to finish (175 d of age). Pigs were administered M. hyopneumoniae and PRRSV vaccines at 7 and 21 d of age, respectively, or both at 21 d old and then challenged with both M. hyopneumoniae and PRRSV at 49 d old. Significant (P < 0.05) differences were observed between the 2 vaccinated challenged groups in average daily weight gain, nasal shedding of M. hyopneumoniae, M. hyopneumoniae-specific interferon-γ secreting cells, and macroscopic and microscopic lung lesions. Induction of interleukin-10 following PRRSV vaccination does not interfere with the immune responses induced by M. hyopneumoniae vaccine. The present study demonstrated that the single-dose vaccination regimen for M. hyopneumoniae and PRRSV vaccine is efficacious for controlling coinfection with M. hyopneumoniae and PRRSV based on clinical, microbiological, immunological, and pathological evaluation.