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Plasmodium vivax genetic selection and further adaptations to sympatric vector species in southern Mexico

Lilia Gonzalez Cerón 1 ; Marbella Ovilla-Muñoz 1 ; Mario Henry Rodríguez 1 ; Frida Santillán 1 ; Juan Eugenio Hernández 1 ; María del Carmen Rodríguez 1 ; Jesús Martínez-Barnetche 1 ; Cuauhtémoc Villarreal-Treviño 1
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Background: In order to extend our knowledge on P. vivax transmission in Southern Mexico, we analyzed the variation of ookinete genes and the 18S ribosomal RNA type S from parasites producing different mosquito infectivity pattern. Methods: P. vivax infectivity pattern was obtained by using infected bloods from symptomatic patients and simultaneously fed An. albimanus and An. pseudopunctipennis. Then, the number of infected mosquitoes and the oocyst numbers for both species were counted. For parasite isolates, the polymorphism of ookinete genes and the ribosomal 18S rRNA were examined. Results: Parasites lots that produced infection in at least one mosquito species, exposed only nonsynonymous mutations in ookinete genes, but CelTOS was conserved. The two variants of 18S rRNA (Sal I and Thai; Li et al., 2001) were detected. Parasites compatible to An. albimanus and no infective to An. pseudopunctipennis had genotype resembling Sal I strain (Pv1). Whereas, parasites of different and conserved haplotype (Pv2), either produced high oocyst infection rate in An. pseudopunctipennis and low infection rate in An. albimanus (Pv2a), or similar oocyst infection rate in both mosquito species (Pv2b). Pv2 had Pvs25 130T, Pvs28 87D/110N, SOAP V74, CTRP M888/G1754, Chitinase (a proportion of these isolates had one extra copy of domain NGSGSGSGGETETGGESG; named Chit-V) and 18S rRNA- Thai. Moreover, parasites Pv2 with Chit-V produced higher proportion of An. albimanus with oocyst infection than parasites expressing wild Chitinase. Conclusions: Parasites of Sal I type are adapted to An. albimanus and widely distributed in the Mesoamerican region. While, parasites Pv2 with divergent haplotype showed certain biological plasticity. Parasites migrated to this region were likely selected by a naturally susceptible An. pseudopunctipennis followed by parasiteadaptations to An. albimanus.Further genomic and functional studies could provide a better understandingof parasite-vector compatibility and adaptation processes in southern Mexico. This work was funded by CONACyT-México-CB-2009-01-131247.