BACKGROUND: Mycobacterium avium subspecies paratuberculosis is the cause of a common disease in dairy herds. Early diagnosis of paratuberculosis infection can improve Johne’s disease control programs.OBJECTIVES: This study aimed to compare the sensitivity, and specificity to methods; blood serum ELISA and stool Nested-PCR for the detection of Mycobacterium avium subspecies paratuberculosis infection in dairy cattle.METHODS: A commercial ELISA kit was used to perform the absorbed ELISA test, which was conducted after exposing serum samples to Mycobacterium phlei antigens to limit cross-reactions. Nested-PCR test was performed using nucleotide sequences related to specific MAP gene fragments, i.e. IS900.RESULTS: As a result of the ELISA antibodies kit, out of the total 2203 serum samples, 112 samples were positive (5.08 %) and 2091 samples were negative (94.92 %). The results of Nested-PCR tests of rectal feces showed that out of 59 cows with the positive results in serum ELISA, 47 (79.66 %) samples were positive and 12 (20.34 %) samples were negative. Moreover, out of 31 cattle with a negative result on the ELISA test, 15 (48.38%) and 16 cattle (51.62 %) had positive and negative results, respectively, on the nested PCR tests of the feces samples.CONCLUSIONS: Due to the low sensitivity of PCR compared to ELISA, the positive and negative predictive values, and the accuracy of ELISA test, as well as the high cost and time-consuming nature of PCR and the need for more and more complex facilities than ELISA, the authors concluded that ELISA is a more suitable method for screening and epidemiological studies than PCR.

Bovine herpesvirus 6 (BoHV6) belongs to the Herpesviridae family, Gammaherpesvirinae subfamily and Macavirus genus. It is common in cattle, but was also detected in American bison (Bison bison) and water buffalo (Bubalus bubalis). The aim of the experiment was to develop an ELISA for serological examination of cattle sera for the presence of anti-BoHV6 specific antibodies.

Infection with Coxiella burnetii causes significant economic impact and poses zoonotic risk to people exposed to livestock, yet few studies in South Africa have assessed seroprevalence of C. burnetii infection and no information is available for goats. Very little information is available regarding risk factors and outcomes of C. burnetii infection in peri-urban farming areas where widespread mixing of ruminants occurs. This study estimated the seroprevalence of C. burnetii infection among communally farmed goats in an area adjacent to the densely populated Gauteng province. Sera were collected from 216 goats in 39 herds, and questionnaires were completed to establish management practices as potential risk factors. C. burnetii antibody testing was done by ELISA. Thirty two out of 216 goats tested positive for C. burnetii antibodies and the overall seroprevalence, adjusted for sampling weights and clustering, was 18.4% (95% confidence interval [CI]: 12.2% - 23.5%). The intraclass correlation coefficient was 0.06, indicating low-to-moderate clustering. Multiple logistic regression showed age was significantly associated with seropositivity, with higher seroprevalence in animals ≥ 19 months old (26%) than animals ≤ 6 months old (6%) (odds ratio [OR]: 6.6; p = 0.010). We concluded C. burnetii infection is common in goats in Moretele and a potential cause of abortion in goats and poses the potential zoonotic disease risk. CONTRIBUTION: Despite the threats posed on animal health and productivity, scant information is published on C. burnetii in South Africa. This research established preliminary estimates of C. burnetii seroprevalence. The research is original from a South African perspective, relevant to Africa and focused on infectious disease in livestock.

Cowdria polymorphic gene 1 (cpg1, Erum2510, ERUM_RS01380) has been shown to induce 30% and 100% protection in sheep immunised by deoxyribonucleic acid (DNA) prime combined with DNA boost and DNA prime combined with protein boost, respectively, against heartwater infection via needle challenge. To localise its antigenic regions for inclusion in a multi-epitope DNA vaccine against heartwater, Erum2510 was cleaved into five overlapping subfragments. These subfragments were expressed individually in an Escherichia coli host expression system and evaluated for their ability to induce proliferative responses, Th1 and Th2 cytokines (interferon gamma [IFN-γ] and interleukin 4 [IL-4]) via enzyme-linked immunospot (ELISpot), quantitative real time polymerase chain reaction (qRT-PCR) and flow cytometry. Recombinant (r)proteins 3 and 4 were shown to induce immunodominant Th1 and Th2 immune responses characterised by the secretion of effector cytokines IFN-γ and IL-4 in addition to differential messenger ribonucleic acid (mRNA) expression of tumour necrosis factor (TNF), IL-2, IL-1, IL-18, IL-10, transforming growth factor (TGF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and inducible nitric oxide synthase (iNOS). Thirty-seven overlapping synthetic peptides (16 mer) spanning the lengths of these immunodominant rproteins were synthesised and assayed. A peptide pool comprising p9 and p10 derived from rprotein 3 induced a Th1-biased immune response. A peptide pool comprising p28 and p29 derived from rprotein 4 induced a mixed Th1 and Th2 immune response characterised by secretion of IFN-γ and differential mRNA expression of IL-1, IL-2, IL-10, IL-12, iNOS, TGF, TNF and GM-CSF. Only one of the peptides (p29) induced secretion of IL-4. Phenotypic analysis showed significant activation of cluster of differentiation 8+ (CD8+), cluster of differentiation 4+ (CD4+) and B+ lymphocyte populations. Findings suggest that Erum2510 rproteins and synthetic peptides can induce both cellular and humoral immune responses, thereby implicating their importance in protection against heartwater. CONTRIBUTION: This study will facilitate the design of an effective multi-epitope DNA vaccine against heartwater that will contribute to control this economically important disease in sub-Saharan Africa and beyond.

Cats are the only definitive host of Toxoplasma gondii (T. gondii) that shed millions of un-sporulated oocysts. The current study aimed at evaluating the serological and histopathological potential ratio of T. gondii oocysts shedding and re-shedding kittens. Blood and fecal samples collected from fifty-seven un-weaned kittens from various districts of Cairo Governorate, Egypt. All kittens serologically screened for T. gondii using the Latex agglutination test (LAT), and fecal materials inspected daily for oocysts. Only proven seronegative un-shedding kittens employed in the three experimental re-shedding studies using the three T. gondii strain types II, III, and I with the third trial focusing on the ability of re-shedding with corticosteroid therapy.  One kitten corresponding to each type sacrificed for histo-pathological assay and IgM/IgG serum antibodies recorded along the trials course using ELISA. The overall sero-negative percentage was 59.7%, with 35.1 and 24.6% in shedding and un-shedding ones respectively. The shedding number of oocysts /100 mg/feces scored (7, 5 and 3); (30, 15 and 7); (20, 10 and 5) corresponding and sequence to the three T. gondii strain types I, II and III respectively. In addition, the average IgM/IgG ELISA titers recorded significance variations sequence to the three strain types. Corticosteroids therapy stimulates re-shedding ability for the third time. The findings concluded that kittens shed oocysts at a high rate; regard shedding and re-shedding qualities as a critical component in developing oocyst-borne human and animal toxoplasmosis effects. Strong protection against vaccinated cats are required, as is close interaction between cats and farm animals.