ABSTRACT
The protein forms of transporter associated with antigen processing, subunit 2 (TAP2), differ either by amino acid substitutions (Thr374Ala, Ile379Val, Ile467Val, Thr565Ala, Val577Met, Cys651Arg, and Ala665Thr) or by a truncation (Gln687Stop) of 17 amino acid residues at the C-terminus. Nonsynonymous single nucleotide polymorphisms (N-SNPs) causing these amino acid variations except 577Val were detected in genomic DNA samples from North American Caucasians (n = 76), Brazilians (n = 148), Rwandans (n = 285), and Zambians (n = 117). Exclusive (100%) and nearly exclusive (>95%) linkage disequilibrium was seen with a number of N-SNPs. The average heterozygosity at any given dimorphic site ranged from 7.3% to 44.6%, and at least four N-SNPs showed clear population specificity. N-SNP combinations alone led to the identification of 16 relatively common alleles, which appeared to form at least three lineages. Further analyses of 101 cDNA samples from Brazilians detected nine expressed TAP2 alleles, four of which matched the official assignments. Genetic complexity at the TAP2 locus was further enhanced by two out of five synonymous SNPs (S-SNPs), especially the GGT386GGG (Gly) that had similar heterozygosity rates in Caucasians (28.9%), Rwandans (33.3%), and Zambians (33.3%). Overall, distribution of both synonymous and nonsynonymous SNPs in the various ethnic groups examined here conformed well to the Hardy-Weinberg equilibrium, and between 57.9% and 77.0% of subjects in each ethnic group were heterozygous with two TAP2 alleles predicted to differ by at least one amino acid residue. Such complexity of TAP2 polymorphisms, in the form of SNPs as well as alleles, is likely to complicate the analyses of disease associations and haplotype structures in the HLA class II region.
Subject(s)
ATP-Binding Cassette Transporters/genetics , Black People/genetics , Genetic Variation , White People/genetics , ATP Binding Cassette Transporter, Subfamily B, Member 3 , Alleles , Amino Acid Sequence , Base Sequence , Brazil , DNA , Evolution, Molecular , Genotype , Humans , North America , Polymerase Chain Reaction , Polymorphism, Single NucleotideABSTRACT
Because of the frequency of ocular toxoplasmosis and its occurrence in multiple siblings in southern Brazil, a population-based household survey was performed to better understand the epidemiologic characteristics of the disease in this region. Of 1,042 individuals examined, 184 (17.7%) were deemed to have ocular toxoplasmosis on the basis of conservative assessment of ophthalmic findings. Of those with ocular toxoplasmosis, 183 (99.5%) had specific IgG antibodies, compared with only 140 of 181 age-matched control subjects (77.4%; P less than .001). The prevalence of ocular toxoplasmosis was 0.9% in 1- to 8-year-olds, 4.3% in 9- to 12-year-olds, 14.3% in 13- to 16-year-olds, and 21.3% (95% confidence interval, 18.6% to 24.2%) in all individuals 13 years or older. The prevalence of ocular toxoplasmosis in this population was more than 30 times higher than previous estimates for the same condition elsewhere. The low prevalence in the young children we studied supplements previous data suggesting that, in this population, ocular toxoplasmosis is a sequela of postnatal rather than congenital infection.
Subject(s)
Toxoplasmosis, Ocular/epidemiology , Adolescent , Adult , Aged , Animals , Brazil/epidemiology , Child , Child, Preschool , Female , Fundus Oculi , Humans , Immunoglobulin G/analysis , Male , Middle Aged , Prevalence , Risk Factors , Toxoplasma/immunology , Toxoplasmosis, Ocular/diagnosisABSTRACT
During a 29-month period, we studied enteric infection in 70 families from a pediatric practice in suburban Washington, D.C. Fecal adenoviruses were detected in stools of 18 patients by tissue culture and electron microscopic procedures. From 6 through 11 months of age, the incidence of fecal adenoviruses associated with enteritis was seven per 100, and of confirmed enteric adenoviruses (EAds), three per 100 individuals per year. All EAds belonged to subgenus G (type 41). All three patients with EAds had diarrhea; two had vomiting and one had fever, but none required hospitalization. Ten of the 15 patients with non-EAds were younger than 2 years, and 60% had diarrhea, 40% had vomiting, and 20% had fever. Combined gastrointestinal and respiratory symptoms occurred more often in those who shed non-EAds (three of 11) than in matched controls (two of 48, P = 0.04). An adenovirus was detected in approximately 6% of gastroenteritis episodes, and confirmed EAds were present in approximately 2% of episodes of gastroenteritis in children younger than 2 years of age. None of the contacts of patients with non-EAds shed such virus in their stools. None of nine family contacts of those with EAd appeared to shed adenovirus in stool. In contrast, rotavirus spread readily to exposed adults (25% of 65) and children (56% of 62) when a child in similar families had rotavirus infection.
Subject(s)
Adenoviridae Infections/epidemiology , Adenoviridae/isolation & purification , Feces/microbiology , Gastroenteritis/etiology , Adolescent , Adult , Age Factors , Child , Child, Preschool , Diarrhea, Infantile/epidemiology , Diarrhea, Infantile/etiology , District of Columbia , Gastroenteritis/epidemiology , Humans , Infant , Infant, Newborn , Longitudinal Studies , Maryland , Microbiological Techniques , VirginiaABSTRACT
Forty-seven % of 4,205 individuals living in a Puerto Rican community developed Shigella sonnei dysentery. Questionnaire and, where relevant, clinical evaluation of 1,970 patients and the remaining 2,235 unaffected residents disclosed no cases of Reiter's syndrome (RS). Among the possible explanations for failure to observe any cases is the important suggestion that S. sonnei is not arthritogenic.