Cryptosporidium parvum- B-cells as a route to control

Lead Research Organisation: University of Liverpool
Department Name: Institute of Infection and Global Health

Abstract

Cryptosporidium parvum infection presents a major threat to calf health and survival as a global cause of enteric disease. Calves under the age of 2 months are 41 times more likely to shed oocysts in comparison with animals aged 4 months or above. Moreover, quality of colostrum is a risk factor for developing diarrhoea while calves receiving prophylactic treatment or born to dams receiving prophylactic treatment were less likely to develop disease.

The majority of animals develop protective immunity after infection such that prevalence levels in older animals decrease. Limited protective immunity under experimental conditions can be induced with a variety of vaccine candidates; however, given that calves are the major at-risk age group, immunisation post-birth is logistically and immunologically a difficult task. Attempts to immunise pregnant heifers has had limited success in providing transfer of antibody to calves in utero. Moreover, current management practices on dairy farms result in dairy calves spending limited time post-birth with dams meaning there are limited opportunities for colostrum intake.

When veterinary intervention is required current treatment utilizes halofuginone, paromomycin and fluid therapy. Despite individual studies detailing the efficacy of halofuginone a recent meta-analysis has suggested that the level of heterogeneity amongst these make it impossible to discern an overall beneficial effect. While paromomycin is registered as being effective against Gram-negative and Gram-positive bacteria, any beneficial effects of its use may likely arise from control of an intestinal dysbiosis as opposed to targeting C. parvum directly. Moreover, the continued use of paromomycin and halofuginone in this manner is contradictory to the nature of anti-microbial resistance stewardship expected by the public, WHO, and statutory veterinary bodies globally.

Hybridoma technology has rapidly advanced the use of monoclonal antibodies (mAb) in a therapeutic setting. However, this has mainly been confined to mouse and human clinical settings. The need to overcome serum sickness - i.e. hypersensitivity reactions to the Fc region - means mAb raised in mice now must be humanised prior to clinical use. This approach has met with limited progress in veterinary medicine with an anti-IL-31 caninized being the only modified mAb on market. Genetic moralisation of B-cells is a method to overcome this limitation. Genetic immortalisation of B-cells thorough overexpression of Bcl-6 and Bxl-cl has been described for a number of species, including large animals, and has shown therapeutic potential for human infectious disease.

This project aims to take advantage of the natural protective immunity that develops during C. parvum infection and genetically immortalise bovine B-cells. Animals will be selected based on clinical signs and being oocyst positive will be blood sampled to isolate and immortalise B-cells. Thereafter the functional characteristics of the cognate antibody from these cells will be tested for neutralising or protective capacity. In addition, B-cells will be characterised for their productive capacity and the stability of neutralising antibodies will be assessed in milk replacer.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
BB/M011186/1 30/09/2015 29/09/2023
2270203 Studentship BB/M011186/1 30/09/2019 31/12/2023 Ellen Tiffney