Size polymorphism and low sequence diversity in the locus encoding the Plasmodium vivax rhoptry neck protein 4 (PvRON4) in Colombian isolates

Abstract

BackgroundDesigning a vaccine against Plasmodium vivax has focused on selecting antigens involved in invasion mechanisms that must have domains with low polymorphism for avoiding allele-specific immune responses. The rhoptry neck protein 4 (RON4) forms part of the tight junction, which is essential in the invasion of hepatocytes and/or erythrocytes; however, little is known about this locus’ genetic diversity.MethodsDNA sequences from 73 Colombian clinical isolates from pvron4 gene were analysed for characterizing their genetic diversity; pvron4 haplotype number and distribution, as well as the evolutionary forces determining diversity pattern, were assessed by population genetics and molecular evolutionary approaches.Results ron4 has low genetic diversity in P. vivax at sequence level; however, a variable amount of tandem repeats at the N-terminal region leads to extensive size polymorphism. This region seems to be exposed to the immune system. The central region has a putative esterase/lipase domain which, like the protein’s C-terminal fragment, is highly conserved at intra- and inter-species level. Both regions are under purifying selection.Conclusions pvron4 is the locus having the lowest genetic diversity described to date for P. vivax. The repeat regions in the N-terminal region could be associated with immune evasion mechanisms while the central region and the C-terminal region seem to be under functional or structural constraint. Bearing such results in mind, the PvRON4 central and/or C-terminal portions represent promising candidates when designing a subunit-based vaccine as they are aimed at avoiding an allele-specific immune response, which might limit vaccine efficacy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1563-4) contains supplementary material, which is available to authorized users.

On the Evolution and Function of Plasmodium vivax Reticulocyte Binding Surface Antigen (pvrbsa)

“…A previous study has suggested that American populations are structured ( Taylor et al, 2013 ); this pattern has also been observed in other P. vivax antigens in Colombia ( Forero-Rodriguez et al, 2014a , b ; Buitrago et al, 2016 ), hence migration was the last force evaluated here. The haplotype network inferred by using all available sequences did not have clear structuring; pvrbsa haplotypes were shared by different countries, even around the world.…”

“…A percentage of sites under positive selection were identified in P. vivax and other species regarding the aBSREL method ( Figure 2A ). This pattern has also been observed in other genes, suggesting species-specific adaptation during parasite evolution ( Muehlenbein et al, 2015 ; Buitrago et al, 2016 ; Garzon-Ospina et al, 2016 ). Evidence of positive selection was found in PvRBSA-B ( Figure 2 and Tables 3 , 4 ), agreeing with the frequency spectrum-based test results.…”

“…Worldwide, the pvrbsa encoding region had 44 segregating sites (47, taking encoding and non-encoding regions into account) giving 70 haplotypes ( Supplementary Data Sheet 1E ). The pvrbsa π value (0.0080 ± 0.0002) was lower than that observed for other Mrz surface proteins [ pvmsp1 , π > 0.05200 ( Valderrama-Aguirre et al, 2011 ; Garzon-Ospina et al, 2015 ); pvmsp3α , π > 0.0349 ( Mascorro et al, 2005 ; Garzon-Ospina et al, 2015 ); pvmsp7C , π = 0.0548; pvmsp7H , π = 0.0357; pvmsp7I , π = 0.0430 ( Garzon-Ospina et al, 2012 ); pvmsp7E , π = 0.0573 ( Garzon-Ospina et al, 2014 )], but similar to that found in pvama1 [π = 0.0067 ( Gunasekera et al, 2007 ; Garzon-Ospina et al, 2015 )] and pvdbp [π = 0.0101 ( Nobrega de Sousa et al, 2011 )] and higher than pvmsp7 ( -A π = 0.0002, -K π = 0.0025, -F π = 0.0008, and - L π = 0.0006) ( Garzon-Ospina et al, 2011 ; Garzon-Ospina et al, 2014 ), pvmsp8 (π = 0.0022) ( Pacheco et al, 2012 ), pvmsp10 (π = 0.0002) ( Garzon-Ospina et al, 2011 ; Pacheco et al, 2012 ), pv12 (π = 0.0004), pv38 (π = 0.0026) and pv41 (π = 0.0037) ( Forero-Rodriguez et al, 2014a , b ; Wang et al, 2014 ) or rhoptry proteins [ rap1 , π = 0.00088, rap2 , π = 0.00141, and ron4 , π = 0.0004 ( Garzon-Ospina et al, 2010 ; Pacheco et al, 2010 ; Buitrago et al, 2016 )].…”

Plasmodium vivax Cell Traversal Protein for Ookinetes and Sporozoites (CelTOS) Functionally Restricted Regions Are Involved in Specific Host-Pathogen Interactions

“…Genetic differentiation analysis revealed that a Thai/Iranian population was greatly differentiated from American populations (Peru, Mexico, and Colombia), this was to be expected due to the distance between these populations. Significant values were observed in Colombia between Chocó and the other subpopulations which could have resulted from structuration in Colombia (limited gene flow amongst populations), as described earlier for other antigens (Forero-Rodriguez et al, 2014;Buitrago et al, 2016;Camargo-Ayala et al, 2018).…”

Receptor-ligand and parasite protein-protein interactions inPlasmodium vivax: Analysing rhoptry neck proteins 2 and 4

“…PvRON2 and PvRON4 ability to interact specifically with RBC was thus evaluated to advance the functional characterisation of P. vivax RONs; this was followed by determining binary interactions between (Hossain et al, 2012;; they contained the regions encoding the P. vivax central (PvRON2-RI) and carboxyl terminal (PvRON2-RII) regions ( Figure 1a). A PvRON4 region located towards the carboxyl terminal extreme was amplified ( Figure 1a); it is highly conserved at intraspecies and interspecies level and is under purifying selection, contrary to that reported for the amino terminal region having extensive size polymorphism (Buitrago, Garzon-Ospina, & Patarroyo, 2016). Selected regions were cloned in pRE4 vector in frame with herpes simplex virus (HSV) glycoprotein D signal peptide and transmembrane domain thereby enabling proteins to be expressed and anchored to cell membrane (Cohen et al, 1988).…”