In-House Developed ELISA Indicates High Prevalence of Anti- Echinococcus granulosus IgG in Sheep Population-An Update from Pakistan
Cystic echinococcosis (CE) is a World Health Organization (WHO)-listed neglected tropical farm economy jeopardizing and public health concern disease. This study was aimed at furnishing sero-epidemiological baseline data of CE in sheep in Pakistan, where data are non-existent. For this purpose, two sheep-rich provinces of Pakistan were selected, and 728 sheep sera were collected using probability proportional to size (PPS) statistical technique. Epidemiological information was recorded on a questionnaire for the estimation of potential risk factors.
The serum samples were analyzed for IgG antibodies against Echinococcus granulosus using an in-house-developed EgAgB-based ELISA kit. The overall seroprevalence recorded was 21.98% (160/728) in the tested sheep, suggesting higher seropositivity in sheep from Punjab (23.73%) as compared to Khyber Pakhtunkhwa (KPK) (19.04%). The overall apparent prevalence observed by this ELISA method was almost similar to the calculated true prevalence (21.77%).
Prevalence was significantly different (p < 0.05) among sheep from different districts. Higher prevalence was found in females (22.54%, OR 1.41), age group > 5 years (29.66%, OR 1.64), crossbreeds (42.85%, OR 2.70), and sheep with pasture access (25.96%, OR 3.06). Being in age group > 5 years and having pasture access were the factors significantly associated with seropositivity (p < 0.05). This study provides serological evidence of E. granulosus infection in sheep and can be used as a model for ante-mortem screening of the sheep globally.
Mice Immunized with IgG Anti–Sheep Red Blood Cells (SRBC) Together With SRBC Have a Suppressed Anti-SRBC Antibody Response but Generate Germinal Centers and Anti–IgG Antibodies in Response to the Passively Administered IgG.
Antigen-specific IgG antibodies, passively administered together with large particulate antigens such as erythrocytes, can completely suppress the antigen-specific antibody response. The mechanism behind has been elusive. Herein, we made the surprising observation that mice immunized with IgG anti-sheep red blood cells (SRBC) and SRBC, in spite of a severely suppressed anti-SRBC response, have a strong germinal center (GC) response.
- This occurred regardless of whether the passively administered IgG was of the same allotype as that of the recipient or not. Six days after immunization, the GC size and the number of GC B cells were higher in mice immunized with SRBC alone than in mice immunized with IgG and SRBC, but at the other time points these parameters were similar.
- GCs in the IgG-groups had a slight shift toward dark zone B cells 6 days after immunization and toward light zone B cells 10 days after immunization.
- The proportions of T follicular helper cells (TFH) and T follicular regulatory cells (TFR) were similar in the two groups.
- Interestingly, mice immunized with allogeneic IgG anti-SRBC together with SRBC mounted a vigorous antibody response against the passively administered suppressive IgG.
- Thus, although their anti-SRBC response was almost completely suppressed, an antibody response against allogeneic, and probably also syngeneic, IgG developed. This most likely explains the development of GCs in the absence of an anti-SRBC antibody response.
Occurrence of anti-Neospora caninum and anti-Toxoplasma gondii IgG antibodies in goats and sheep in western Maranhão, Brazil.
Neosporosis and toxoplasmosis are parasitic diseases which can cause reproductive problems in goats and sheep. The current study aimed to determine the occurrence of anti-Neospora caninum and anti-Toxoplasma gondii IgG antibodies in goats and sheep from the districts of Amarante do Maranhão and Buritirana, Imperatriz microregion, western area of Maranhão State, northeastern Brazil, and to assess factors associated to infection by these etiologic agents.
Blood samples from 110 animals (46 goats and 64 sheep) from five herds were collected, and indirect immunofluorescence assay was used for serological testing. Of 46 goat samples, 17.39% (n = 8) showed anti-N. caninum antibodies and 4.35% (n = 2) anti-T. gondii, while of 64 sheep samples 4.69% (n = 3) and 18.75% (n = 12) showed anti-N. caninum and anti-T. gondii antibodies, respectively. No significant difference regarding the presence of domestic cats and/or dogs on the property and veterinary care was seen for both etiologic agents studied.
However, food supplementation and animal reproductive failure were significantly (p < 0.05) for N. caninum among sheep and goats, respectively. The current study showed that goats and sheep in western Maranhão are exposed to N. caninum and T. gondii. It is the first evidence of these agents in small ruminants in this region.
The control of antibody diversity during IgM and IgG anti–sheep red cell responses in mice
The isoelectric heterogeneity of both IgM and IgG murine anti-sheep red cell serum antibodies has been examined using an adaptation of published methods. It was found that the IgM spectra were restricted in a characteristic manner, implying oligoclonality. In cell transfer experiments, the T cell dependency of the IgM responses was confirmed. Further, helper cells appeared to switch on IgG antibody production and, simultaneously, recruit many novel IgG-forming clones into the response. The pattern of the IgM oligoclonality was attributed in part to the inheritance of genes at, or closely linked to, the Igl heavy chain locus. These findings are discussed in relation to current research on the regulation of diversity.
The interaction of the Facb fragment of rabbit anti–sheep red cell IgG with guinea pig macrophages, and human monocytes and granulocytes
Yasmeen et al. (J. Immun. 110, 1706-1709, 1973) have previously reported on the binding requirements of the guinea pig peritoneal macrophage Fc receptor. The C gamma 3 domain fragments of human IgG1, in contrast to the C gamma 2 domain fragment, were able to bind to these macrophages, as demonstrated by both direct and indirect rosette tests. We now report that we have been unable to show binding by the C gamma 2-bearing rabbit Facb fragment to either peritoneal or alveolar macrophages of the guinea pig.
This evidence is therefore in agreement with the hypothesis proposed by Yasmeen et al. (1973) that the C gamma 2 homology region does not contribute directly to the binding requirements for this cell type. The same protein, rabbit anti-sheep erythrocyte Facb, when coated on sheep erythrocytes, did not form rosettes with human granulocytes, but did form some rosettes with human monocytes.
Anti-Toxoplasma gondii and anti-Neospora caninum antibodies in sheep from Paraná state, South Brazil: prevalence and associated factors
The aim of this study was to evaluate the seroprevalence and factors associated with the presence of anti-Toxoplasma gondii and anti-Neospora caninum antibodies in sheep from Paraná state. The detection of antibodies for T. gondii and N. caninum was performed by homemade and commercial indirect ELISA, respectively. Multiple logistic regression analysis was used to verify the factors associated with the seroprevalence.
Antibodies anti-T. gondii and anti-N. caninum were observed in 42.7% and in 17.6% of the animals, respectively. The protective factors associated to seropositive were “some level of confinement” (full or semi-extensive confinement) (OR=0.53) for T. gondii and “use of skilled labor” (OR=0.64) for N. caninum.
The risk factors were “presence of cats” (OR=1.75) for T. gondii and “feeding of dogs with sheep placental remains” (OR=1.79) for N. caninum. In addition, to presenting a significant and simultaneous seroprevalence for both agents (9.9% of the animals), the results also indicate that deficiencies in management and environmental sanitation, the presence of reservoirs, and types of exploitation enhance the seropositivity. Thus, studies like this might support sanitary programs and public policies for the prevention of T. gondii and N. caninum in the sheep herds of Paraná state.