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Project

Contagious Bovine Pleuropneumonia: cattle breed susceptibility and development of improved diagnostics

Contagious bovine pleuropneumonia (CBPP) is a severe respiratory disease affecting cattle. CBPP is highly contagious causing a high morbidity and mortality especially when introduced into naïve populations. In sub Saharan Africa, CBPP is enzootic thus a major hindrance in food security continuing to cause huge losses, prevent access to live animal trade markets locally and internationally and lower the market value of cattle due to poor condition. CBPP is caused by Mycoplasma mycoides subsp. mycoides (Mmm). Mmm is a member of the Mycoplasma mycoides cluster, which includes four other Mycoplasma. Members of the Mycoplasma mycoides cluster have genetic and phenotypic similarities. This makes the diagnosis of Mmm difficult. Current available OIE-approved diagnostics are a complement fixation test (CFT) and a competitive ELISA (cELISA). These tests detect CBPP at herd level. The diagnosis of CBPP is paramount to its control and treatment. Diagnosis often involves clinical symptoms that lead to further investigations including laboratory tests. A difference in immune responses to various livestock diseases has been associated with the genes found in different breeds of animals. Initial work investigated the difference in CBPP disease presentation for two common zebu breeds of cattle in Kenya and observed that the improved boran zebu has less clinical signs and pathology than the small east African zebu when artificially infected with the same challenge material. Theses preliminary findings may contribute to the choice of Mmm antigens to investigate for the development of a CBPP diagnostic assay. To evaluate potential diagnostic targets, 17 Mmm protein sequences were chosen on literature and used for expression of recombinant Mmm proteins. The diagnostic usefulness of these proteins was further tested against sera from CBPP affected and disease-free cattle. Identified Mmm recombinant proteins were combined in a multi- antigen ELISA (cocktail) to evaluate if sensitivity could be further improved. The most immunogenic proteins combined in a cocktail ELISA (Translation elongation factor Tu- MSC0636 and Hypothetical protein-MSC0136) were further developed into a lateral flow rapid diagnostic test that can be used in the field. The study reports comparable detection ability of the cocktail ELISA to the currently recommended OIE serological assays, CFT and cELISA. The study also reports on Mmm lipoprotein Q-N terminal (LppQ-N), an immunogenic region that is specific for Mmm in the Mycoplasma mycoides cluster. LppQ- N was evaluated in shorter fragments to improve on expression and examine its diagnostic potential. One region of the five LppQ- N fragments namely, F3-R1 showed similar detection ability as the full length LppQ-N and was recommended for further evaluation in order to be considered for inclusion in the multi- antigen ELISA and in the lateral flow test to improve on the sensitivity for rapid detect of CBPP in the sub Saharan Africa.

Date:1 Oct 2011 →  26 Jun 2023
Keywords:Diagnostics, Contagious bovine pleuropneumonia
Disciplines:Diagnostics, Laboratory medicine, Medicinal products
Project type:PhD project