Browsing by Author "Olea-Popelka, Francisco"

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    Cytokine gene expression assay as a diagnostic tool for detection of Mycobacterium bovis infection in warthogs (Phacochoerus africanus)
    (Nature Research (part of Springer Nature), 2019) Roos, Eduard O .; Scott, Leere A.; Ndou, Sedzani; Olea-Popelka, Francisco; Buss, Peter E.; De Klerk-Lorist, Lin-Mari; Warren, Robin M.; Van Helden, Paul D.; Sylvester, Tashnica T .; Miller, Michele A.; Parsons, Sven D. C.
    ENGLISH ABSTRACT: Mycobacterium bovis infection has been described in many wildlife species across Africa. However, diagnostic tests are lacking for many of these, including warthogs (Phacochoerus africanus). Most literature on suids has focused on using serological tools, with few studies investigating the use of cell-mediated immune response (CMI) assays. A recent study showed that warthogs develop measurable CMI responses, which suggests that cytokine gene expression assays (GEAs) may be valuable for detecting M. bovis-infection, as shown in numerous African wildlife species. Therefore, the aim of the study was to develop GEAs capable of distinguishing between M. bovis-infected and uninfected warthogs. Whole blood was stimulated using the QuantiFERON-TB Gold (In-Tube) system, using ESAT-6 and CFP-10 peptides, before determining the relative gene expression of five reference (B2M, H3F3A, LDHA, PPIA and YWHAZ) and five target (CXCL9, CXCL10, CXCL11, IFNG and TNFA) genes through qPCR. The reference gene H3F3A was the most stably expressed, while all target genes were significantly upregulated in M. bovis-infected warthogs with the greatest upregulation observed for CXCL10. Consequently, the CXCL10 GEA shows promise as an ante-mortem diagnostic tool for the detection of M. bovis-infected warthogs.
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    Measuring antigen-specific responses in Mycobacterium bovis-infected warthogs (Phacochoerus africanus) using the intradermal tuberculin test
    (BMC (part of Springer Nature), 2018) Roos, Eduard O.; Olea-Popelka, Francisco; Buss, Peter E.; Hausler, Guy; Warren, Robin M.; Van Helden, Paul D.; Parsons, Sven D. C.; De Klerk-Lorist, Lin-Mari; Miller, Michele Ann
    Background: Bovine tuberculosis (bTB) caused by Mycobacterium bovis has previously been diagnosed in warthogs and infection can be highly prevalent (> 30%) in endemic areas. Thus, warthogs could potentially be an important species to consider as sentinels for disease surveillance. However, disease surveillance is dependent on availability of accurate diagnostic assays and only a few diagnostic tests have been investigated for warthogs. Furthermore, the tests that have been used in this species require laboratory equipment and trained personnel to obtain results. Therefore, this study investigated the use of the intradermal tuberculin test (ITT) to screen warthogs for bTB, which can be done with minimal equipment and under field conditions by most veterinarians and other qualified professionals. Changes in skin fold thickness measurements at the bovine purified protein derivative (PPD) administration site, between 0 and 72 h, were compared with differential changes between the bovine and avian PPD sites, for 34 warthogs, to evaluate the performance when different interpretation criteria for the ITT was used. Results: Using an increase of 1.8 mm or more at the bovine PPD site as a cut-off for positive responders, 69% of 16 M. bovis culture-positive warthogs had a positive test result, with 100% of the 18 culture-negative warthogs considered as test negative. When a differential of 1.2 mm or more in skin fold thickness at the bovine PPD compared to the avian PPD site was used as a cut-off for the comparative ITT, 81% of culture-positive warthogs were considered as test positive, with 100% of culture-negative warthogs considered as test negative. Conclusion: The findings in this study suggest that the ITT is a promising tool to use when screening warthogs for M. bovis infection.