In-House Developed ELISA Indicates High Prevalence of Anti- Echinococcus granulosus IgG in Sheep Population-An Update from Pakistan

February 15, 2022 0 Comments

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 Egranulosus infection in sheep and can be used as a model for ante-mortem screening of the sheep globally.

Mice Immunized with IgG AntiSheep Red Blood Cells (SRBC) Together With SRBC Have a Suppressed Anti-SRBC Antibody Response but Generate Germinal Centers and AntiIgG 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.

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