Volume 9 Supplement 2

Parasite to Prevention: Advances in the understanding of malaria

Open Access

Strain specific protective immunity induced by pre-erythrocytic infection of toque monkeys with Plasmodium cynomolg

  • Wathsala Wijayalath1,
  • Sandie Cheesman3,
  • Jagath Rajakaruna1,
  • Sudath Weerasinghe1,
  • Gamini Kapilananda1,
  • Kamal Gamage2,
  • Kamal Perera2,
  • Shiroma Handunnetti4,
  • Richard Carter3 and
  • Sisira Pathirana1
Malaria Journal20109(Suppl 2):P58

https://doi.org/10.1186/1475-2875-9-S2-P58

Published: 20 October 2010

Strain specific protective immunity (SSPI) was investigated using two strains of Plasmodium cynomolgi, Pc746 and PcCeylon, in toque monkey. Two groups of monkeys were immunized against either Pc746 (n=5) or PcCeylon (n=4), by giving bites with 2-4 sporozoite-infected Anopheles tessellates mosquitoes per monkey. Primary blood infection was prevented by simultaneous chloroquine cover and secondary, hypnozoite-induced, blood infection was prevented by treating the monkeys one month later with primaquine. The two immunized groups and a group of unimmunized monkeys (n=4) were given a mixed-strain sporozoite challenge infection, 140 and 100 days respectively after immunization. Parasite DNA was collected for 5-8 consecutive days after parasitaemia reached 0.05% or above. The proportions of the two parasite strains in these samples were quantified using a PyrosequencingTM assay based on SNPs in MSP1 and CSP genes. In subsequent blood infections in immunized monkeys the earliest recorded proportion of parasites of an immunizing strain was significantly lower than its proportion in monkeys immunized against a heterologous strain (P=0.014 and 0.027 for the two SNPs) and the proportions of an immunizing strain tended to decline during the period of sample collection. These results show that a parasite strain specific protective immunity to P. cynomolgi was indcued following a sporozoite induced pre-erythrocytic infection. This immunity may have been directed against the liver stages or against the blood stage parasites, or against both

Declarations

Acknowledgements

Financial support by NSF, Sri Lanka (research grant -RG/2005/HS/14 and scholarship - NSF/SCH/2004/08) and NRC, Sri Lanka 05-66 is acknowledged. SC and RC were supported by a Wellcome Trust Programme Grant.

Authors’ Affiliations

(1)
Malaria Research Unit, Dept of Parasitology, Faculty of Medicine, University of Colombo
(2)
Animal House, Faculty of Medicine, University of Colombo
(3)
School of Biological Sciences, Institute of Immunology & Infection Research, University of Edinburgh
(4)
Institute of Biochemistry, Molecular Biology and Biotechnology, University of Colombo

Copyright

© Pathirana et al; licensee BioMed Central Ltd. 2010

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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