Genetic polymorphism of the serine rich antigen N-terminal region in Plasmodium falciparum field isolates from Brazil

Abstract

In this work we investigated the frequency of polymorphism in exon II

Evaluation of the genetic polymorphism of Plasmodium falciparum P126 protein (SERA or SERP) and its influence on naturally acquired specific antibody responses in malaria-infected individuals living in the Brazilian Amazon

“…In Africa, Asia and South America, including Brazil [ 24 , 26 , 36 ], only one single OR fragment type (OR-I or OR-II) appeared in P. falciparum malaria infected individuals while in our study, mixed infection (both OR-I and ORII) was detected for the first time in inhabitants of both villages with high frequency in Peixoto de Azevedo. Also noteworthy are the differences in the OR fragment frequencies among P. falciparum isolates from Peixoto de Azevedo when compared with the isolates from other endemic areas.…”

“…The sequences herein analysed, further confirm a limited degree of genetic polymorphism in the P126 OR domain, namely variation in the number of octamer repeats (OR-I five or OR-II six) and non-synonymous substitutions in repeat units [ 24 , 26 , 36 ]. In addition, there was a remarkable similarity between the P126 OR domain of P. falcipar um from Candeias do Jamari in 1993 and 2002, a difference of 9 years, suggesting that this portion of the P126 gene was both genetically homogeneous and temporally stable, and despite differing from the Candeias do Jamari groups in terms of frequencies and infection complexity, the Peixoto de Azevedo group shared an identical degree of polymorphism in the P126 OR domain.…”

“…The high mixed infection and single OR-I fragment prevalence in Peixoto de Azevedo in comparison with isolates from the Candeias do Jamari group as well as groups from a myriad of other geographical areas, is probably due to: i) an immunological status of this population, since studied individuals from this village, mainly migrants from malaria-free areas, have been inhabiting a malaria endemic area for an average of four years, ii) a relatively recent introduction of the variant into this population as a consequence of the gold miners' nomadic behaviour within the Amazon, facilitating new variant spread throughout the region and iii) the differences in the biological development of this variant in man and/or its invertebrate host. Although in a Brazilian endemic area [ 26 ] only single infection had previously been detected, this study's relatively small sample size may account for an underestimation of mixed infection scope.…”

“…The occurrence of polymorphism in the OR domain, which encodes B- and T-epitopes [ 25 ] involved in the induction of the protective immunity, may provide a mechanism for parasites to evade immune response induced by either natural exposition to infections or vaccine. Recently, analyses of P. falciparum isolates (n = 52) from three areas of the Brazilian Amazon have identified the occurrence of the two P126 OR fragments, the most frequent constituting six octamer repeats [ 26 ]. The study of P126 OR domain polymorphism influence on the naturally acquired specific antibody responses in individuals living in malaria-endemic areas may provide valuable insights for vaccine development against this high priority disease.…”