Whole blood transcriptome analysis of Mycoplasma mycoides subsp mycoides-infected cattle confirms immunosuppression but does not reflect local inflammation

Contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides subsp. mycoides (Mmm), is a severe respiratory disease of cattle responsible for major economic losses in sub-Saharan Africa. Disease control relies mainly on the use of empirically attenuated vaccines that provide limited protection. Thus, understanding the virulence mechanisms used by Mmm as well as the role of the host immune systemin disease development, persistence, and control is a prerequisite for the development of new, rationally designed control strategies. The aim of this study was to assess the use of whole blood transcriptome analysis to study cattle-Mmm interactions, starting by the characterization of the bovine response to Mmm infection during the acute form of the disease. For that purpose, we compared the transcriptome profile of whole blood from six cattle, before challenge by contact with Mmm infected animals and at the appearance of first clinical signs, using a bovine microarray. Functional analysis revealed that 680 annotated genes were differentially expressed, with an overwhelming majority of down-regulated genes characterizing an immunosuppression. The main bio-functions affected were "organismal survival", "cellular development, morphology and functions" and "cell-to cell signaling and interactions". These affected functions were consistent with the results of previous in vitro immunological studies. However, microarray and qPCR validation results did not highlight pro-inflammatory molecules (such as TNF alpha, TLR2, IL-12B and IL-6), whereas inflammation is one of the most characteristic traits of acute CBPP. This global gene expression pattern may be considered as the result, in blood, of the local pulmonary response and the systemic events occurring during acute CBPP. Nevertheless, to understand the immune events occurring during disease, detailed analyses on the different immune cell subpopulations, either in vivo, at the local site, or in vitro, will be required. Whole blood transcriptome analysis remains an interesting approach for the identification of bio-signatures correlating to recovery and protection, which should facilitate the evaluation and validation of novel vaccine formulations

Confirmation of antibodies against L-tryptophan-like epitope in human African trypanosomosis serological diagnostic

Antibodies directed against L-tryptophan epitope (WE - W for tryptophan, E for epitope), a constant epitope borne by variant surface glycoproteins (VSG), have been detected in sera of all 152 Human African Trypanosomosis (HAT) patients from Angola. The WE is present in VSG hydrophobic regions of the C terminal domains. In the assay, L-tryptophan was linked to bovine serum albumin (BSA) with glutaraldehyde to synthesize W-G-BSA conjugate which was used in an enzyme-linked immunosorbent assay (ELISA) to detect the antibodies. A significant difference was found between HAT patients and controls confirming previous results obtained with a lower number of patients in Congo. A diagnostic test based on this synthetic epitope, especially in combination with other tests, might improve the HAT diagnostic test in field conditions.Key words: Tryptophan, enzyme-linked immunosorbent assay (ELISA), human African trypanosomosis, serological diagnostic