Specific Antibody and Interferon-Gamma Responses Associated with Immunopathological Forms of Bovine Paratuberculosis in Slaughtered Friesian Cattle

Abstract

Mycobacterium avium subsp. paratuberculosis (MAP) infection causes a chronic granulomatous inflammatory regional enteritis in ruminants. Cell-mediated immune responses are assumed to be protective and therefore, to be associated with its more delimited lesion types, while humoral responses are mainly associated with diffuse histopathological lesions. However, this duality of immune responses has been recently questioned. The aim of this study was to assess the relationship between both types of immunological responses and the type and extension of intestinal lesions and the presence of MAP in bovine tissues. Standard histopathological examinations, two microbiological procedures (culture and real time PCR (rtPCR)), as well as MAP specific antibody and interferon gamma (IFN-γ) release assays (IGRA) were performed on tissues and blood of 333 slaughtered Holstein-Friesian animals. Paratuberculous lesions were observed in 176 (52.9%) of the animals and overall MAP detection rates were estimated at 13.5% and 28.5% for tissue culture and rtPCR, respectively. Unlike the relatively constant non-specific IFN-γ release, both the antibody levels and the specific IFN-γ release significantly increased with tissue damage. Delimited immunopathological forms, which accounted for 93.2% of all forms, were mostly related to positive testing in the IGRA (38.4%) whereas diffuse ones (6.8%) were associated with antibody seropositivity (91.7%). However, since the frequency of positive immune responses in both tests increased as the lesions severity increased, polarization of Th1/Th2 responses was less prominent than expected. MAP was detected in the majority of ELISA-positive animals (culture+: 90%, rtPCR+: 85%) but the bacteria was only confirmed in the 36.1% of IGRA-positive animals by any of the two microbiological tests. In terms of diagnosis, the antibody test was a good indicator of advanced tissue damage (diffuse forms), but the IGRA did not associate well with more delimited forms or with MAP detection.

Latent infections are the most frequent form of paratuberculosis in slaughtered Friesian cattle

“…Despite this, there was good agreement between ELISA testing and histology for patent PTB. In this study, 69.7% of all patent cases and more specifically, 92.9% of cases with diffuse enteritis were detected by ELISA, confirming that this immunological test is a useful indicator of severe tissue damage (Vazquez et al, 2013). However, sensitivity and agreement sharply decreased for the latent PTB cases.…”

“…If PTB compatible lesions were identified, Ziehl-Neelsen (ZN) staining was applied to an additional section in order to identify acid-fast bacilli (AFB). Histopathological lesions were classified as focal, multifocal, diffuse lymphoplasmacytic, diffuse intermediate and diffuse histiocytic, according to the classification of PTB immunopathological types proposed for cattle by González et al (2005) and modified by Vazquez et al (2013). Briefly, focal lesions were small well-delimited granulomas containing mostly macrophages, some lymphocytes and Langhan's giant cells.…”

“…For cattle, immunopathological types were summarized into f ive types: focal, multifocal, diffuse lymphocytic or lymphoplasmacytic, diffuse intermediate and diffuse multibacillary or histiocytic, based on an exhaustive histological characterization of lesions (González et al, 2005) and its nomenclature revision (Vazquez et al, 2013). This classification acknowledges the existence of one type, the focal type, that would represent an infectious state similar to that of latency that is considered the most frequent in human tuberculosis (Flynn & Chan, 2001;Corbett et al, 2003), but that has not been well def ined in cattle mycobacteriosis (Cassidy, 2006;Van Rhijn et al, 2008).…”

Development and Evaluation of a Novel Multicopy-Element-Targeting Triplex PCR for Detection of Mycobacterium avium subsp. paratuberculosis in Feces

“…The ileocecal lymph node, ileocecal valve, and jejunum were cultured separately for tissue culture. (v) For histopathological findings (20), the numbers used were 2 for patent forms (PF), encompassing diffuse multibacillary, diffuse intermediate, diffuse paucibacillary lesions, and multifocal lesions (21), 1 for latent forms (LF) or focal lesions, and 0 for apparently free (AF) of PTB (i.e., when no PTB-compatible lesions were observed).…”

Sensitive and Specific Enzyme-Linked Immunosorbent Assay for Detecting Serum Antibodies against Mycobacterium avium subsp. paratuberculosis in Fallow Deer

“…Large numbers of AFB were detected in the diffuse multibacillary lesions, and a granulomatous infiltrate consisting of epithelioid cells, lymphocytes, macrophages, and numerous Langhans giant cells was observed. The four types of histopathological lesions were further grouped into one of two categories using epidemiological criteria outlined previously, latent forms (focal lesions) and patent forms (multifocal and diffuse lesions) (21).…”