Effect of malaria transmission reduction by insecticide-treated bed nets (ITNs) on the genetic diversity of Plasmodium falciparum merozoite surface protein (MSP-1) and circumsporozoite (CSP) in western Kenya

Malaria Journal

Research

Wangeci Gatei¹  Geofrey Muluvi²  Ann Muia²  James Njunge²  William A Hawley³  Ya Ping Shi³  Mary J Hamel³  Kim A Lindblade³  Laurence Slutsker³  Simon K Kariuki⁴  Dianne J Terlouw⁵  Feiko ter Kuile⁵  Penelope A Phillips-Howard⁵  Bernard L Nahlen⁶ 

[1] Atlanta Research and Education Foundation, Atlanta, GA, USA;Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, USA;Biochemistry and Biotechnology Department, Kenyatta University, Nairobi, Kenya;Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, USA;Centre for Vector Biology and Control Research, Kenya Medical Research Institute, Kisumu, Kenya;Child and Reproductive Health Group, Liverpool School of Tropical Medicine, Liverpool, UK;President’s Malaria Initiative, Washington, DC, USA;

关键词: Malaria;    Parasite diversity;    MSP-1;    CSP;    Transmission;    Bed nets;   

DOI  :  10.1186/1475-2875-12-295

 received in 2013-06-04, accepted in 2013-08-19,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundAlthough several studies have investigated the impact of reduced malaria transmission due to insecticide-treated bed nets (ITNs) on the patterns of morbidity and mortality, there is limited information on their effect on parasite diversity.MethodsSequencing was used to investigate the effect of ITNs on polymorphisms in two genes encoding leading Plasmodium falciparum vaccine candidate antigens, the 19 kilodalton blood stage merozoite surface protein-1 (MSP-119kDa) and the Th2R and Th3R T-cell epitopes of the pre-erythrocytic stage circumsporozoite protein (CSP) in a large community-based ITN trial site in western Kenya. The number and frequency of haplotypes as well as nucleotide and haplotype diversity were compared among parasites obtained from children <5 years old prior to the introduction of ITNs (1996) and after 5 years of high coverage ITN use (2001).ResultsA total of 12 MSP-119kDa haplotypes were detected in 1996 and 2001. The Q-KSNG-L and E-KSNG-L haplotypes corresponding to the FVO and FUP strains of P. falciparum were the most prevalent (range 32–37%), with an overall haplotype diversity of > 0.7. No MSP-119kDa 3D7 sequence-types were detected in 1996 and the frequency was less than 4% in 2001. The CSP Th2R and Th3R domains were highly polymorphic with a total of 26 and 14 haplotypes, respectively detected in 1996 and 34 and 13 haplotypes in 2001, with an overall haplotype diversity of > 0.9 and 0.75 respectively. The frequency of the most predominant Th2R and Th3R haplotypes was 14 and 36%, respectively. The frequency of Th2R and Th3R haplotypes corresponding to the 3D7 parasite strain was less than 4% at both time points. There was no significant difference in nucleotide and haplotype diversity in parasite isolates collected at both time points.ConclusionHigh diversity in these two genes has been maintained overtime despite marked reductions in malaria transmission due to ITNs use. The frequency of 3D7 sequence-types was very low in this area. These findings provide information that could be useful in the design of future malaria vaccines for deployment in endemic areas with high ITN coverage and in interpretation of efficacy data for malaria vaccines based on 3D7 parasite strains.

【 授权许可】

CC BY   
© Kariuki et al.; licensee BioMed Central Ltd. 2013