Author:
|
Longley, Rhea J.; Franca, Camila T.; White, Michael T.; Kumpitak, Chalermpon; Sa-Angchai, Patiwat; Gruszczyk, Jakub; Hostetler, Jessica B.; Yadava, Anjali; King, Christopher L.; Fairhurst, Rick M.; Rayner, Julian C.; Tham, Wai-Hong; Nguitragool, Wang; Sattabongkot, Jetsumon; Mueller, Ivo
|
Abstract:
|
BACKGROUND: Thailand is aiming to eliminate malaria by the year
2024. Plasmodium vivax has now become the dominant species
causing malaria within the country, and a high proportion of
infections are asymptomatic. A better understanding of antibody
dynamics to P. vivax antigens in a low-transmission setting,
where acquired immune responses are poorly characterized, will
be pivotal for developing new strategies for elimination, such
as improved surveillance methods and vaccines. The objective of
this study was to characterize total IgG antibody levels to 11
key P. vivax proteins in a village of western Thailand. METHODS:
Plasma samples from 546 volunteers enrolled in a cross-sectional
survey conducted in 2012 in Kanchanaburi Province were utilized.
Total IgG levels to 11 different proteins known or predicted to
be involved in reticulocyte binding or invasion (ARP, GAMA, P41,
P12, PVX_081550, and five members of the PvRBP family), as well
as the leading pre-erythrocytic vaccine candidate (CSP) were
measured using a multiplexed bead-based assay. Associations
between IgG levels and infection status, age, and spatial
location were explored. RESULTS: Individuals from a
low-transmission region of western Thailand reacted to all 11 P.
vivax recombinant proteins. Significantly greater IgG levels
were observed in the presence of a current P. vivax infection,
despite all infected individuals being asymptomatic. IgG levels
were also higher in adults (18 years and older) than in
children. For most of the proteins, higher IgG levels were
observed in individuals living closer to the Myanmar border and
further away from local health services. CONCLUSIONS: Robust IgG
responses were observed to most proteins and IgG levels
correlated with surrogates of exposure, suggesting these
antigens may serve as potential biomarkers of exposure,
immunity, or both. |