We have explored the humoral response of check details the villagers to MSP1 block2 using synthetic peptides displaying numerous sequence variants. Serological studies have included a cross-sectional study to measure point prevalence at the village level before a rainy season, a prospective study to Selleckchem ICG-001 explore the relationship between the presence of antibodies to MSP1 block2 at enrolment and protection from clinical malaria episodes during the following five months of intense transmission, and longitudinal follow up of individuals to study temporal antibody variation. This

showed evidence for family-specific responses possibly exerting a balancing selection, but gave no support to the notion of antibody selection for variant sequence alleles. Results Pfmsp1 block2 PCR genotyping: distribution of allelic families A total of 306 samples were successfully genotyped by semi-nested PCR. Overall 524 PCR fragments were generated (Table 1). There were 247, 145 and 132 fragments assigned to the K1, Mad20 and RO33 allelic families, respectively. Based on fragment size polymorphism, 32 and 23 K1-type and Mad20-type alleles Tipifarnib datasheet could be identified [see Additional file 1]. All RO33 fragments were of the same size. The family frequencies were 47%, 28% and 25% for K1, Mad20 and RO33, respectively. The relative

proportion of the three allelic families (Figure 1) did not show significant temporal fluctuations (Pearson test, Chi2 = 14.99; p = 0.663), was not influenced by age (Fisher’s exact test, p = 0.813), gender (idem, p = 0.45), β-globin type (idem, p = 0.678 for AA vs. AS; p = 0.923 AA vs. AS vs. other β-globin variants), ABO blood group (idem p = 0.688) or Rhesus blood group (idem p = 0. 390). Table 1 Number of isolates studied by calendar year of survey

and successfully genotyped for the Pfmsp1 block2 locus by nested PCR and gene sequencing     PCR genotyping Sequencing year of survey No samples studied No samples typed No alleles detected Mean No alleles detected/sample No PCR fragments sequenced 1990 23 23 46 2,00 27 1991 30 29 49 1,69 32 1992 30 29 43 1,48 33 1993 37 36 63 1,75 45 1994 35 34 54 1,59 37 1995 38 33 51 1,55 40 1996 46 38 68 1,79 48 1997 26 25 46 1,84 29 1998 52 44 76 1,73 51 1999 19 15 28 1,87 16 Figure 1 Temporal distribution of the relative proportion of the three allelic families below in Dielmo during 1990-99. Alleles were assigned to one of three allelic families by nested PCR. Distribution is shown by calendar year. The number of samples typed each year is shown in Table 1. Colour symbols: black: K1-types, white: Mad20-types, grey RO33 types. Note that hybrid alleles were not distinguished from the Mad20-types and are included in the Mad20 group. Many samples contained more than one Pfmsp1 block2 type. The average multiplicity of infection estimated from the number of fragments detected (estimated moi – see Methods) was 1.