Gene expression profile suggests that pigs (Sus scrofa) are susceptible to Anaplasma phagocytophilum but control infection

BACKGROUND Anaplasma phagocytophilum infects a wide variety of hosts and causes granulocytic anaplasmosis in humans, horses and dogs and tick-borne fever in ruminants. Infection with A. phagocytophilum results in the modification of host gene expression and immune response. The objective of this research was to characterize gene expression in pigs (Sus scrofa) naturally and experimentally infected with A. phagocytophilum trying to identify mechanisms that help to explain low infection prevalence in this species. RESULTS For gene expression analysis in naturally infected pigs, microarray hybridization was used. The expression of differentially expressed immune response genes was analyzed by real-time RT-PCR in naturally and experimentally infected pigs. Results suggested that A. phagocytophilum infection affected cytoskeleton rearrangement and increased both innate and adaptive immune responses by up regulation of interleukin 1 receptor accessory protein-like 1 (IL1RAPL1), T-cell receptor alpha chain (TCR-alpha), thrombospondin 4 (TSP-4) and Gap junction protein alpha 1 (GJA1) genes. Higher serum levels of IL-1 beta, IL-8 and TNF-alpha in infected pigs when compared to controls supported data obtained at the mRNA level. CONCLUSIONS These results suggested that pigs are susceptible to A. phagocytophilum but control infection, particularly through activation of innate immune responses, phagocytosis and autophagy. This fact may account for the low infection prevalence detected in pigs in some regions and thus their low or no impact as a reservoir host for this pathogen. These results advanced our understanding of the molecular mechanisms at the host-pathogen interface and suggested a role for newly reported genes in the protection of pigs against A. phagocytophilum.

Effect of cattle on Salmonella carriage, diversity and antimicrobial resistance in free-ranging wild boar (Sus scrofa) in northeastern Spain

Salmonella is distributed worldwide and is a pathogen of economic and public health importance. As a multi-host pathogen with a long environmental persistence, it is a suitable model for the study of wildlife-livestock interactions. In this work, we aim to explore the spill-over of Salmonella between free-ranging wild boar and livestock in a protected natural area in NE Spain and the presence of antimicrobial resistance. Salmonella prevalence, serotypes and diversity were compared between wild boars, sympatric cattle and wild boars from cattle-free areas. The effect of age, sex, cattle presence and cattle herd size on Salmonella probability of infection in wild boars was explored by means of Generalized Linear Models and a model selection based on the Akaike's Information Criterion. Prevalence was higher in wild boars co-habiting with cattle (35.67%, CI 95% 28.19-43.70) than in wild boar from cattle-free areas (17.54%, CI 95% 8.74-29.91). Probability of a wild boar being a Salmonella carrier increased with cattle herd size but decreased with the host age. Serotypes Meleagridis, Anatum and Othmarschen were isolated concurrently from cattle and sympatric wild boars. Apart from serotypes shared with cattle, wild boars appear to have their own serotypes, which are also found in wild boars from cattle-free areas (Enteritidis, Mikawasima, 4:b:- and 35:r:z35). Serotype richness (diversity) was higher in wild boars co-habiting with cattle, but evenness was not altered by the introduction of serotypes from cattle. The finding of a S. Mbandaka strain resistant to sulfamethoxazole, streptomycin and chloramphenicol and a S. Enteritidis strain resistant to ciprofloxacin and nalidixic acid in wild boars is cause for public health concern.

Tonsils of the soft palate do not mediate the response of pigs to oral vaccination with heat-inactivated Mycobacterium bovis

Mycobacterium bovis causes animal tuberculosis (TB) in cattle, humans, and other mammalian species, including pigs. The goal of this study was to experimentally assess the responses of pigs with and without a history of tonsillectomy to oral vaccination with heat-inactivated M. bovis and challenge with a virulent M. bovis field strain, to compare pig and wild boar responses using the same vaccination model as previously used in the Eurasian wild boar (Sus scrofa), to evaluate the use of several enzyme-linked immunosorbent assays (ELISAs) and lateral flow tests for in vivo TB diagnosis in pigs, and to verify if these tests are influenced by oral vaccination with inactivated M. bovis. At necropsy, the lesion and culture scores were 20% to 43% higher in the controls than those in the vaccinated pigs. Massive M. bovis growth from thoracic tissue samples was observed in 4 out of 9 controls but in none of the 10 vaccinated pigs. No effect of the presence or absence of tonsils was observed on these scores, suggesting that tonsils are not involved in the protective response to this vaccine in pigs. The serum antibody levels increased significantly only after challenge. At necropsy, the estimated sensitivities of the ELISAs and dual path platform (DPP) assays ranged from 89% to 94%. In the oral mucosa, no differences in gene expression were observed in the control group between the pigs with and without tonsils. In the vaccinated group, the mRNA levels for chemokine (C-C motif) receptor 7 (CCR7), interferon beta (IFN-β), and methylmalonyl coenzyme A mutase (MUT) were higher in pigs with tonsils. Complement component 3 mRNA levels in peripheral blood mononuclear cells (PBMC) increased with vaccination and decreased after M. bovis challenge. This information is relevant for pig production in regions that are endemic for M. bovis and for TB vaccine research.