The online version of this article (doi:10.1186/1475-2875-11-305) contains supplementary material, which is available to authorized users.
The authors declare that they have no competing interests.
MEMF participated in the design of the study, carried out the genotyping studies, performed the statistical analyses and drafted the manuscript. CTA carried out diagnostics on all avian blood samples. DAL carried out all of the mosquito studies. SIJ conceived of the study, participated in its design and coordination and oversaw the drafting of the manuscript. All authors assisted in editing early drafts and read and approved the final manuscript.
The avian disease system in Hawaii offers an ideal opportunity to investigate host-pathogen interactions in a natural setting. Previous studies have recognized only a single mitochondrial lineage of avian malaria (Plasmodium relictum) in the Hawaiian Islands, but cloning and sequencing of nuclear genes suggest a higher degree of genetic diversity.
In order to evaluate genetic diversity of P. relictum at the population level and further understand host-parasite interactions, a modified single-base extension (SBE) method was used to explore spatial and temporal distribution patterns of single nucleotide polymorphisms (SNPs) in the thrombospondin-related anonymous protein (trap) gene of P. relictum infections from 121 hatch-year amakihi (Hemignathus virens) on the east side of Hawaii Island.
Rare alleles and mixed infections were documented at three of eight SNP loci; this is the first documentation of genetically diverse infections of P. relictum at the population level in Hawaii. Logistic regression revealed that the likelihood of infection with a rare allele increased at low-elevation, but decreased as mosquito capture rates increased. The inverse relationship between vector capture rates and probability of infection with a rare allele is unexpected given current theories of epidemiology developed in human malarias.
The results of this study suggest that pathogen diversity in Hawaii may be driven by a complex interaction of factors including transmission rates, host immune pressures, and parasite-parasite competition.
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- Analysis of the trap gene provides evidence for the role of elevation and vector abundance in the genetic diversity of Plasmodium relictum in Hawaii
Margaret E M Farias
Carter T Atkinson
Dennis A LaPointe
Susan I Jarvi
- BioMed Central
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