Exposure toMycobacterium aviuminduces low-level protection fromMycobacterium bovisinfection but compromises diagnosis of disease in cattle

Abstract

SummaryWe assessed the effect of exposure to Mycobacterium avium on the development of immune responses and the pathogenesis of disease observed following Mycobacterium bovis challenge. A degree of protection against M. bovis was observed in calves which were pre-exposed to M. avium as assessed by the extent of lesions and bacterial load compared to the M. bovis alone group. The immune response following M. bovis challenge in cattle previously inoculated with M. avium was biased towards antigens (PPD) present in M. avium , whereas the response following M. bovis alone was biased towards antigens present in M. bovis , indicating an imprinting of memory to avian antigens on T lymphocytes. A consequence of the memory to M. avium antigens was failure to diagnose M. bovis infection by the skin test or the IFNg g g g assay in some of the animals which had lesions of tuberculosis at necropsy. The use of M. bovis specific antigens ESAT-6 and CFP-10 increased IFNg g g g test specificity in animals previously exposed to M. avium but the responses to these antigens were lower than those observed in animals exposed to M. bovis alone. The implication is that responses to M. avium , although providing some immunity, may mask diagnosis of M. bovis infection, even when specific antigens are employed, potentially contributing to disease transmission in the field.

Identification of proteins from tuberculin purified protein derivative (PPD) by LC-MS/MS

“…bovis are also of great interest, as their use could result in a test able to differentiate infected from vaccinated animals 41 . We detected four such antigens in bovine PPD but all of them (MPT64, CFP21, CFP10 and ESAT-6) have previously been investigated as antigens for development of diagnostic tests 13,16,42 capable of differentiating BCG-vaccinated animals from those infected with bovine tuberculosis [13][14][15][16] .…”

Is Mycobacterium bovis in the environment important for the persistence of bovine tuberculosis?

“…Apart from being potentially infectious to cattle, either by ingestion or more likely by creation of an aerosol during olfactory investigation, there is a possibility that the presence of environmental M. bovis could compromise test-andslaughter programmes for bTB control and help explain bTB persistence. Sensitization of cattle to other species of environmental mycobacteria can compromise cattle immune responses to subsequent vaccination with BCG (Buddle et al 2002), and can cause cattle to remain skin-test negative even though they are potentially infectious (Hope et al 2005).…”

Differential Effects of Viral Vectors on Migratory Afferent Lymph Dendritic CellsIn VitroPredict Enhanced ImmunogenicityIn Vivo

“…For detection of IFN-␥ expression by enzyme-linked immunosorbent spot (ELISpot) assay, the cells were transferred to a nitrocellulose-backed 96-well MultiScreen hemagglutinin (HA) plate (Millipore, Bedford, MA), which had been coated with 100 l of 8 g/ml anti-bovine IFN-␥ MAb CC330. The cells were incubated for 24 h at 37°C, and the assay continued as previously described (26). Secretion of IFN-␥ and interleukin-10 (IL-10) was detected by enzyme-linked immunosorbent assay (ELISA) as previously described (10,25,34).…”