Genetic Fingerprints of Parasites Causing Severe Malaria in a Setting of Low Transmission in Sudan

Abstract

In this study we intended to examine the extent of genetic diversity of Plasmodium falciparum parasites causing severe malaria (SM). For this purpose, 100 parasite isolates were obtained from patients with SM and uncomplicated malaria, from an area of low and unstable malaria transmission in Sudan. The diversity of infection (DOI) was estimated by relating the number of the different parasite genotypes that were detected to the total number of parasites that were genotyped (parasite population/subpopulation). We used different molecular markers individually (pfcrt-76, pfmr1-86, GLURP size and MSP2 family and size) and as a group to set a multilocus genetic profile for each parasite isolate. The DOI as estimated by MSP2 and GLURP was 0.553 and 0.435, respectively. However, combination of all four molecular markers (multilocus genetic profile) revealed a fingerprint pattern of genetic diversity with a DOI of 0.936, indicating that in SM infection, diversity is the rule and homogeny is the exception. Furthermore, our clinical data suggest that the virulence markers might also be more diverse than expected. In conclusion, the results are unexpected and overturn the assumption that parasites causing SM are a limited subpopulation of virulent parasites or of a clonal nature. However, it was more likely that there was a genetically unique parasite in each infection.

Genetic polymorphisms in the glutamate-rich protein of Plasmodium falciparum field isolates from a malaria-endemic area of Brazil

“…Similarly, studies conducted in low endemicity areas of Honduras, French Guyana and Colombia detected the presence of two, three and five GLURP alleles, respectively ( Ariey et al 1999, Haddad et al 1999, Montoya et al 2003, Barrera et al 2010). Conversely, our observations differ from those made in high endemic areas of Asia and, more strikingly, Africa, where several groups have observed the presence of eight-20 different alleles (Snounou et al 1999, Ranjit et al 2005, A-Elbasit et al 2007, Mlambo et al 2007, Mwingira et al 2011). The limited polymorphic variation that we observed in the gene encoding GLURP may reflect the low endemicity of the area we studied.…”

“…Previous studies of GLURP in low malaria endemicity areas have reported two alleles in Honduras (Haddad et al 1999), three alleles in French Guyana (Ariey et al 1999) and four alleles in Colombia ( Montoya et al 2003). In the high endemicity areas of Africa and Asia, anywhere from eight GLURP alleles in India to 20 alleles in Sudan have been reported (Snounou et al 1999, Ranjit et al 2005, A-Elbasit et al 2007, Mlambo et al. 2007, Mwingira et al 2011).…”

“…It is well recognised that the complexity of infections may vary considerably under different epidemiological scenarios according to the age, gender and immune status of the affected individuals (Bendixen et al 2001, A-Elbasit et al 2007). In the present work, no relationship was established between infection patterns and age, gender or time of residence in a particular malaria endemic area.…”

Genetic polymorphism and amino acid sequence variation in Plasmodium falciparum GLURP R2 repeat region in Assam, India, at an interval of five years

“…Previous studies have reported two GLURP (R2) alleles in Honduras [ 34 ], three in French Guyana [ 35 ] and each four in Colombia [ 36 ] and Brazil [ 37 ] in the area of low endemicity; however in high endemicity areas in Africa and Asia, anywhere from eight in India to twenty GLURP alleles in Sudan were reported respectively [ 18 , 20 , 21 , 38 ]. Current study found eight alleles in Group-A and nine alleles in Group-B, whereas overall ten alleles were found in the total samples compared to eight reported in Orissa [ 20 ].…”

Size and sequence polymorphisms in the glutamate-rich protein gene of the human malaria parasite Plasmodium falciparum in Thailand

“…The percentage of AAU types was calculated by dividing the number of a particular AAU type by the total number of AAU types in one block. The diversity of infection (DOI) was calculated by dividing the number of different parasite genotypes that were detected with the total number of parasites that were genotyped [ 48 ].…”