Comparison of conserved and variable residues between OspC pairs A, I3 and F, I3.

<p><b>Panel A</b> Partial amino acid sequence alignment of OspC types F (top row), A (bottom row) and the chimeric OspC I3 (middle). Only helices α2 through α5 are shown. Black bars indicate regions of sequence identity between the chimeric OspC I3 to the parental OspC types. Colored blocks represent individual amino acids. <b>Panel B</b> Top row: frontal view of the OspC dimer structure; bottom row, view from the top of the structure. The cartoon representation of the OspC dimer is colored from N- to C- terminus in blue to red, respectively. The surface representations show the combined amino acid sequences of pairs OspC A and I3 (left) and OspC F and I3 (center), where polymorphic positions identical within each pair are shown in green and mismatches appear in red. Residues strictly conserved in all 23 OspC proteins appear in light and dark gray.</p

Matrices of cross-reactive antibody binding correlations.

<p>Pearson’s correlation (<i>r</i>) was calculated between all OspC pairs using antibody binding reactivity values for all 55 sera from patients with LD to populate the matrices shown as heat maps. The matrices computed for log₁₀-transformed data (<i>M_D-log</i>), rank transform (<i>M_D-rank</i>) and binary transform (<i>M_D-binary</i>) are shown in the left, middle and right panels, respectively.</p

Twenty most cross-reactive OspC types for sera from patients with Lyme disease.

<p>Twenty most cross-reactive OspC types for sera from patients with Lyme disease.</p

Distribution of Pearson’s <i>r values</i> from OspC cross-reactivity matrices.

<p>The frequency histogram shows the distribution of <i>r</i> values obtained from the OspC cross-reactivity matrices calculated using either the observed (blue bars) or randomized (orange bars) antibody binding profiles and their 3 transform metrics, log₁₀, rank and binary.</p

Multivariate analysis of antibody response to OspC types A, F and the chimera I3.

<p>Log10-transformed intensity of antibody binding to OspC A, F and I3 by sera from 55 human patients with LD (blue dots) and 23 experimental infections of <i>P. leucopus</i> rodents (red dots). Correlation coefficient <i>R²</i> is shown for each comparison.</p

Submicroscopic and asymptomatic Plasmodium falciparum and Plasmodium vivax infections are common in western Thailand - molecular and serological evidence.

BackgroundMalaria is a public health problem in parts of Thailand, where Plasmodium falciparum and Plasmodium vivax are the main causes of infection. In the northwestern border province of Tak parasite prevalence is now estimated to be less than 1% by microscopy. Nonetheless, microscopy is insensitive at low-level parasitaemia. The objective of this study was to assess the current epidemiology of falciparum and vivax malaria in Tak using molecular methods to detect exposure to and infection with parasites; in particular, the prevalence of asymptomatic infections and infections with submicroscopic parasite levels.MethodsThree-hundred microlitres of whole blood from finger-prick were collected into capillary tubes from residents of a sentinel village and from patients at a malaria clinic. Pelleted cellular fractions were screened by quantitative PCR to determine parasite prevalence, while plasma was probed on a protein microarray displaying hundreds of P. falciparum and P. vivax proteins to obtain antibody response profiles in those individuals.ResultsOf 219 samples from the village, qPCR detected 25 (11.4%) Plasmodium sp. infections, of which 92% were asymptomatic and 100% were submicroscopic. Of 61 samples from the clinic patients, 27 (44.3%) were positive by qPCR, of which 25.9% had submicroscopic parasite levels. Cryptic mixed infections, misdiagnosed as single-species infections by microscopy, were found in 7 (25.9%) malaria patients. All sample donors, parasitaemic and non-parasitaemic alike, had serological evidence of parasite exposure, with 100% seropositivity to at least 54 antigens. Antigens significantly associated with asymptomatic infections were P. falciparum MSP2, DnaJ protein, putative E1E2 ATPase, and three others.ConclusionThese findings suggest that parasite prevalence is higher than currently estimated by local authorities based on the standard light microscopy. As transmission levels drop in Thailand, it may be necessary to employ higher throughput and sensitivity methods for parasite detection in the phase of malaria elimination

Submicroscopic and asymptomatic Plasmodium falciparum and Plasmodium vivax infections are common in western Thailand - molecular and serological evidence.

BackgroundMalaria is a public health problem in parts of Thailand, where Plasmodium falciparum and Plasmodium vivax are the main causes of infection. In the northwestern border province of Tak parasite prevalence is now estimated to be less than 1% by microscopy. Nonetheless, microscopy is insensitive at low-level parasitaemia. The objective of this study was to assess the current epidemiology of falciparum and vivax malaria in Tak using molecular methods to detect exposure to and infection with parasites; in particular, the prevalence of asymptomatic infections and infections with submicroscopic parasite levels.MethodsThree-hundred microlitres of whole blood from finger-prick were collected into capillary tubes from residents of a sentinel village and from patients at a malaria clinic. Pelleted cellular fractions were screened by quantitative PCR to determine parasite prevalence, while plasma was probed on a protein microarray displaying hundreds of P. falciparum and P. vivax proteins to obtain antibody response profiles in those individuals.ResultsOf 219 samples from the village, qPCR detected 25 (11.4%) Plasmodium sp. infections, of which 92% were asymptomatic and 100% were submicroscopic. Of 61 samples from the clinic patients, 27 (44.3%) were positive by qPCR, of which 25.9% had submicroscopic parasite levels. Cryptic mixed infections, misdiagnosed as single-species infections by microscopy, were found in 7 (25.9%) malaria patients. All sample donors, parasitaemic and non-parasitaemic alike, had serological evidence of parasite exposure, with 100% seropositivity to at least 54 antigens. Antigens significantly associated with asymptomatic infections were P. falciparum MSP2, DnaJ protein, putative E1E2 ATPase, and three others.ConclusionThese findings suggest that parasite prevalence is higher than currently estimated by local authorities based on the standard light microscopy. As transmission levels drop in Thailand, it may be necessary to employ higher throughput and sensitivity methods for parasite detection in the phase of malaria elimination