Genes differentially expressed in oropharyngeal tonsils and mandibular lymph nodes of tuberculous and nontuberculous European wild boars naturally exposed toMycobacterium bovis

Abstract

Bovine tuberculosis, caused by Mycobacterium bovis (Mycobacterium tuberculosis complex), is a zoonotic disease that affects cattle worldwide. The bacterium infects other animal species, both domesticated and wild, and this range of hosts complicates attempts to control or eradicate the disease. Despite advances in the characterization of the mechanisms involved in host-pathogen interactions and host cell responses to M. tuberculosis complex in human, bovine and mouse cells, differentially expressed genes in tissue biopsies of naturally occurring tuberculous and nontuberculous exposed individuals have been poorly characterized. In this study, differential gene expression was analysed using suppression-subtractive hybridization in oropharyngeal tonsils and mandibular lymph nodes of field-collected tuberculous and nontuberculous European wild boars from a tuberculosis-endemic area of Spain. Real-time PCR and semiquantitative reverse-transcriptase PCR of selected genes confirmed the results of the suppression-subtractive hybridization analysis. Protein expression of selected differentially expressed genes was analysed by radial immunodiffusion or immunohistochemistry. Differential gene expression varied among tuberculous and non-tuberculous groups and between tonsils and lymph nodes. Single and multiple cellular mechanisms were affected, including signal transduction, immune response, inflammation, stress, apoptosis/antiapoptosis, cell structure, adhesion and transport, protein and DNA/RNA metabolism and enzymatic processes. These results demonstrate the modulation of gene expression by mycobacterial infection in tonsils and mandibular lymph nodes of European wild boars naturally exposed to M. bovis, and provide a basis for defining host-pathogen interactions and the mechanism of protective immunity.

Animal-side serologic assay for rapid detection of Mycobacterium bovis infection in multiple species of free-ranging wildlife

“…Suboptimal RT sensitivities found in this study for badgers and possums (51% and 45%, respectively) are in line with previous attempts to detect antibodies to M. bovis in these animals (Buddle et al, 1995;Chambers et al, 2002Chambers et al, , 2008Greenwald et al, 2003). The strong IgG responses in wild boar appear in agreement with the reported observation that Ig heavy and light chains were up-regulated during M. bovis infection (Naranjo et al, 2006). This finding offers the possibility of using serology for large-scale testing of wildlife in epidemiological surveys.…”

Expression of immunoregulatory genes in peripheral blood mononuclear cells of European wild boar immunized with BCG

“…Immuoregulatory genes (Table 1) were selected based on their putative role during mycobacterial infection and/or for their association with resistance to bTB in European wild boar (Naranjo et al, 2006). The genes analyzed herein included Interferon gamma …”

“…The study of gene expression profiles in tissues from infected wild boar may be crucial for the understanding of the regulation of anti-mycobacterial immunity in this wildlife reservoir species. Recently, we demonstrated differential gene expression in tonsils and mandibular lymph nodes of infected and uninfected European wild boar exposed to natural M. bovis infection and identified possible correlates of resistance to 20 bTB in this species (Naranjo et al, 2006;Naranjo et al, 2007a;Naranjo et al, 2007b).…”

“…In all cases, the mean of the duplicate values was used and data for vaccinated/control samples were compared using the Student`s t-test (P=0.05). The work with wildlife species is difficult but allows the analysis of gene expression in naturally infected individuals (Naranjo et al, 2006). One disadvantage of working with wild boar is that fresh blood is not always available in hunted animals.…”

Tonsils of the Soft Palate Do Not Mediate the Response of Pigs to Oral Vaccination with Heat-Inactivated Mycobacterium bovis

“…Previous studies in wild boar analyzed the tonsils as a target organ for mycobacteria, demonstrating that (i) gene expression differs among tuberculous and nontuberculous animals and between tonsils and lymph nodes after natural exposure to M. bovis but also between vaccinated and nonvaccinated animals under experimental conditions, and (ii) differentially regulated molecules of the mandibular lymph nodes and the tonsils are involved in stress/inflammatory responses to mycobacterial infection and may be used as markers for diagnosing TB in wild boar (16)(17)(18)(19)(20).…”