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At least 19 recordsLinked to original sources
PubMed1998

The JC and BK human polyoma viruses appear to be recent introductions to some South American Indian tribes: there is no serological evidence of cross-reactivity with the simian polyoma virus SV40.

In an effort to understand the unusual cytogenetic damage earlier encountered in the Yanomama Indians, plasma samples from 425 Amerindians representing 14 tribes have been tested for hemagglutination inhibition antibodies to the human JC polyoma virus and from 369 Amerinds from 13 tribes for hemagglutination inhibition antibodies to the human BK polyoma virus. There is for both viruses highly significant heterogeneity between tribes for the prevalence of serum antibody titers >/=1/40, the pattern of infection suggesting that these two viruses only relatively recently have been introduced into some of these tribes. Some of these samples, from populations with no known exposure to the simian polyoma virus SV40, also were tested for antibodies to this virus by using an immunospot assay. In contrast to the findings of Brown et al. (Brown, P., Tsai, T. & Gajdusek, D. C. (1975) Am. J. Epidemiol. 102, 331-340), none of the samples was found to possess antibodies to SV40. In addition, no significant titers to SV40 were found in a sample of 97 Japanese adults, many of whom had been found to exhibit elevated titers to the JC and BK viruses. This study thus suggests that these human sera contain significant antibody titers to the human polyoma viruses JC and BK but do not appear to contain either cross-reactive antibodies to SV40 or primary antibodies resulting from SV40 infection.

Adult↗
PubMed2002

MICA polymorphism in South American Indians.

We have studied the MICA alleles of 196 unrelated subjects from three South American Indian tribes (Toba, Wichi and Terena). They are members of isolated tribes located in the Gran Chaco area in northeastern Argentina and in Mato Grosso do Sul in South Central Brazil. Of 55 previously known alleles, nine were observed in South American Indians, compared with 16 that were found in North American Caucasians, suggesting a more restricted allelic distribution of MICA in these tribes. In South American Indians, MICA*00201 was the most frequent allele, with a gene frequency of 33% in Toba, 47% in Wichi and 44% in Terena. MICA*00201, MICA*027 (external domain sequence like MICA*008/TM allele A5) and MICA*010 accounted for more than 90% of all the MICA genes in South American Indians. In North American Caucasians, MICA*00801 (*008/A5.1) accounted for 42% of the genes and was the most common allele. We observed a high degree of linkage disequilibrium between certain alleles of MICA and of HLA-B in the South American Indian populations. Phylogenetic trees constructed using gene frequencies of the transmembrane short tandem repeats in the populations reported here, and in other populations taken from published reports, suggest that South American Indians are more closely related to Asians than to Europeans.

Adult↗
PubMed1980

New studies on the esterase D polymorphism in South American Indians.

A total of 2,490 South American Indians affiliated with 10 tribes were studied for esterases A1, A2, A3, B, D, and carbonic anhydrases 1 and 2. Wide variation was observed in the prevalence of ESD1, the extreme values being 0.44, encountered among the Xikrin, and 0.95, found among the Cashinawa. Seven of the 10 frequencies fell within the interval of 0.66--0.87. These results were integrated with those of earlier surveys. In a general way we observe lower values in the eastern and Atlantic Coast groups, but this is mainly due to the low frequencies found among the Gê tribes and the Caingang, who speak a language which has many affinities with Gê. High prevalences were observed among the tropical forest tribes. A fair amount of intervillage, intratribal variation was found among the Ticuna and Caingang. No variability was detected in the A1, A2, A3, B esterases. In the carbonic anhydrases we confirmed the presence of a "private polymorphism" among the Baniwa.

Alleles↗
PubMed1991

Intestinal helminths in lowland South American Indians: some evolutionary interpretations.

Data on intestinal parasite infections for South American Indians in prehistoric times as revealed by coprolite analysis are being used to support transoceanic migration routes from the Old World to the New World. These same findings on modern semi-isolated aborigines, considered persisting prehistoric patterns, are also of great importance as indicators of pre-Columbian peopling of South America. This is the case for the Lengua Indians from Paraguay, studied in the 1920s, and the Yanomami and the Salumã from Brazil, studied in the 1980s. The intestinal parasitic profile of these groups can be empirically associated with culture change, but no clear correlations with the population biology of their hosts can be made at present because of scarcity of data.

Biological Evolution↗
PubMed1975

Genetic distance analysis of twenty-two South American Indian populations.

Extent of genic variability among 22 tribal groups of South American Indians in terms of net codon differences per locus has been studied on the basis of determinations on ten genetic systems. The possibility of more than one (other than the north-south route, considered by others) migrational pattern is discussed in the light of the existing genetic variability among the Andean highland and the jungle populations. Genic similarities (as measured by gene identity) are related with geographic proximities which reflect the importance of random genetic drift in creating the present genic divergence among these population groups. Although the materials used in this paper form probably only a non-random sample of structural genome, intralocus variance (sampling) is found to contribute only a little in the variabilities of heterozygosity or genetic distance.

Bolivia↗
PubMedDate not supplied

High heterogeneity of apolipoprotein E gene frequencies in South American Indians.

The apolipoprotein E (APOE) polymorphism was investigated in 186 individuals from six South American Indian tribes, and the results integrated with those previously presented for this ethnic group. The three APOE alleles commonly reported in other populations were also observed in South Amerindians with a highly heterogeneous distribution. As in other populations, APOE*3 was the most common allele (51-98%) followed by APOE*4 (2-47%). These two isoforms were identified in all tribes, but APOE*2 was observed among the Wai Wai (2%) and Mataco (4%) only. No previous indications of inter-ethnic admixture were observed among the Wai Wai, but the introduction of this allele among the Mataco through non-Indian sources cannot be excluded.

Alleles↗
PubMedDate not supplied

D1S80 locus variability in South American Indians.

We have studied the hypervariable D1S80 locus in 185 individuals from five South American Indian tribes, integrating these results with previous investigations. Three alleles (*18, *24 and *30) were common to all tribes, but their frequencies varied between northern and southern populations. Brazilian tribes have a high frequency of *30 (average 35%) while in Argentinian and Chilean Indian populations this allele is present, on average, in 7% of the chromosomes only. Allele *24, the most common in other ethnic groups, was observed in 10% and 25% of northern and southern Amerindians respectively. Genetic distance and dendrogram analyses placed the Argentinian and Chilean tribes closer to Brazilian Caucasians, suggesting non-Indian admixture among them.

Alleles↗
PubMedDate not supplied

Gradients of HLA diversity in South American Indians.

Information concerning the HLA-A and -B loci was considered in relation to 3796 Amerindians living in 39 places in South America, data related to HLA-C being based on a smaller subset of 2989 persons distributed among 33 localities. Synthetic gene frequency maps were then constructed using principal-components analysis. Clearly significant longitudinal (principal component 1) and latitudinal (principal components 1, 2, and 3) clines were observed, most probably indicating ancient migration routes.

Alleles↗
PubMed1993

Differences in HLA class II alleles of isolated South American Indian populations from Brazil and Argentina.

We have studied the HLA class II alleles in 277 South American Indians, which included Argentinian tribes from the Gran Chaco: Toba (n = 135), Toba-Pilaga (n = 19), Mataco-Wichi (n = 49), and Xavantes, a tribe from Central Brazil (n = 74). In the Brazilian tribe, only four DR groups were found: DRB1*1602 (gf = 0.303), DRB1*04 including DRB1*0404 (gf = 0.070) and DRB1*0407 (gf = 0.077), DRB1*0802 (gf = 0.265), and DRB1*1402 (gf = 0.303). The HLA class II allele frequencies were similar among the different Argentinian tribes, and 90% of DRB1 alleles belonged to three families: DRB1*04 (including DRB1*0403, DRB1*0404, DRB1*0407, DRB1*0411, and DRB1*0417), DRB1*0802, and DRB1*14 (including DRB1*1402 and DRB1*1406). At the DPB1 locus, we found only seven alleles, the most frequent being DPB1*0402. Comparison of HLA class II alleles with those of North American Indians that we have previously studied shows that the frequency of some HLA class II alleles in Brazilian Xavantes resembles that of North American Indians more than that of the Argentinian Indian tribes. The allele DRB1*0417 was found exclusively in this population.

Adult↗