Dataset Information

Sequence diversity of cytotoxic T cell antigens and satellite marker analysis of Theileria parva informs the immunization against East Coast fever in Rwanda.

ABSTRACT:

Background

East Coast fever (ECF) caused by Theileria parva is endemic in Rwanda. In this study, the antigenic and genetic diversity of T. parva coupled with immunization and field challenge were undertaken to provide evidence for the introduction of ECF immunization in Rwanda.

Methods

Blood collected from cattle in the field was screened for T. parva using ELISA and PCR targeting the p104 gene. Tp1 and Tp2 gene sequences were generated from field samples and from Gikongoro and Nyakizu isolates. Furthermore, multilocus genotype data was generated using 5 satellite markers and an immunization challenge trial under field conditions using Muguga cocktail vaccine undertaken.

Results

Out of 120 samples, 44 and 20 were positive on ELISA and PCR, respectively. Antigenic diversity of the Tp1 and Tp2 gene sequences revealed an abundance of Muguga, Kiambu and Serengeti epitopes in the samples. A further three clusters were observed on both Tp1 and Tp2 phylogenetic trees; two clusters comprising of field samples and vaccine isolates and the third cluster comprising exclusively of Rwanda samples. Both antigens exhibited purifying selection with no positive selection sites. In addition, satellite marker analysis revealed that field samples possessed both shared alleles with Muguga cocktail on all loci and also a higher proportion of unique alleles. The Muguga cocktail (Muguga, Kiambu and Serengeti) genotype compared to other vaccine isolates, was the most represented in the field samples. Further low genetic sub-structuring (F_ST = 0.037) coupled with linkage disequilibrium between Muguga cocktail and the field samples was observed. Using the above data to guide a field immunization challenge trial comprising 41 immunized and 40 control animals resulted in 85% seroconversion in the immunized animals and an efficacy of vaccination of 81.7%, implying high protection against ECF.

Conclusions

Antigenic and genetic diversity analysis of T. parva facilitated the use of Muguga cocktail vaccine in field conditions. A protection level of 81.7% was achieved, demonstrating the importance of combining molecular tools with field trials to establish the suitability of implementation of immunization campaigns. Based on the information in this study, Muguga cocktail immunization in Rwanda has a potential to produce desirable results.

SUBMITTER: Atuhaire DK

PROVIDER: S-EPMC7487574 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Publications

Sequence diversity of cytotoxic T cell antigens and satellite marker analysis of Theileria parva informs the immunization against East Coast fever in Rwanda.

Atuhaire David Kalenzi DK Muleya Walter W Mbao Victor V Bazarusanga Thomas T Gafarasi Isidore I Salt Jeremy J Namangala Boniface B Musoke Antony Jim AJ

Parasites & vectors 20200907 1

<h4>Background</h4>East Coast fever (ECF) caused by Theileria parva is endemic in Rwanda. In this study, the antigenic and genetic diversity of T. parva coupled with immunization and field challenge were undertaken to provide evidence for the introduction of ECF immunization in Rwanda.<h4>Methods</h4>Blood collected from cattle in the field was screened for T. parva using ELISA and PCR targeting the p104 gene. Tp1 and Tp2 gene sequences were generated from field samples and from Gikongoro and Ny ...[more]

PMID: 32894166

Similar Datasets

Project description:BACKGROUND:East Coast fever (ECF) is a devastating disease of cattle and a significant constraint to improvement of livestock production in sub-Saharan Africa. The protozoan parasite causing ECF, Theileria parva, undergoes obligate sexual stage development in its tick vector Rhipicephalus appendiculatus. Tick-borne acquisition and transmission occurs transstadially; larval and nymphal ticks acquire infection while feeding and transmit to cattle when they feed after molting to the next stage. Much of the current knowledge relating to tick-borne acquisition and transmission of T. parva has been derived from studies performed during acute infections where parasitemia is high. In contrast, tick-borne transmission during the low-level persistent infections characteristic of endemic transmission cycles is rarely studied. METHODS:Cattle were infected with one of two stocks of T. parva (Muguga or Marikebuni). Four months post-infection when parasites were no longer detectable in peripheral blood by PCR, 500 R. appendiculatus nymphs were fed to repletion on each of the cattle. After they molted to the adult stage, 20 or 200 ticks, respectively, were fed on two naïve cattle for each of the parasite stocks. After adult ticks fed to repletion, cattle were tested for T. parva infection by nested PCR and dot blot hybridization. RESULTS:Once they had molted to adults the ticks that had fed as nymphs on Muguga and Marikebuni infected cattle successfully transmitted Theileria parva to all naïve cattle, even though T. parva infection was not detectable by nested PCR on salivary gland genomic DNA of a sample of individual ticks. However, a salivary gland homogenate from a single Marikebuni infected tick was able to infect primary bovine lymphocytes. Infection was detected by nested p104 PCR in 3 of 4 calves and detected in all 4 calves by T. parva 18S nested PCR/dot blot hybridization. CONCLUSION:We show that R. appendiculatus ticks are able to acquire T. parva parasites from infected cattle even in the absence of detectable parasitemia. Although infection was undetectable in a sample of individual ticks, cumulatively as few as 20 ticks were able to transmit T. parva to naïve cattle. These results have important implications for our understanding of T. parva transmission by R. appendiculatus in ECF endemic regions.

Dataset Information

Sequence diversity of cytotoxic T cell antigens and satellite marker analysis of Theileria parva informs the immunization against East Coast fever in Rwanda.

Background

Methods

Results

Conclusions

Publications

Sequence diversity of cytotoxic T cell antigens and satellite marker analysis of Theileria parva informs the immunization against East Coast fever in Rwanda.

Similar Datasets

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