Immunoglobulin allotypes (GM and KM) in three Amerindian populations of French Guiana.

We have studied 506 Amerindians from three French Guiana groups: 194 Wayampi, living in Trois-Sauts, and 100 living in the Camopi area; 47 Emerillon also living in the Camopi area and 165 Wayana living on the Litani and Maroni rivers. All samples were tested for G1M (1,2,3,17), G3M (5,6,10,11,13,14,15,16,21,24,28) and KM(1) by the classical method of hemaglutination inhibition. The phenotype and haplotype distributions are presented and have been subjected to factorial analysis of correspondence. Two common GM haplotypes are GM1,17:21,28 and GM1,2,17;21,28 but with an important variation in frequency. A rare haplotype, GM1,17;21R,28, probably the result of a genetic anomaly, is frequent in the Emerillon (17%). These populations show no evidence of Negroid or Caucasian admixtures.

A new approach for interpreting the genetic diversity in space: 'Mobile Site Method'. Application to Gm haplotype distribution of twenty-seven Amerindian tribes from North and Central America.

We present a new approach, called 'Mobile Site Method' (MSM), to the construction of 'genetic similarity maps' more efficient than that described in a preceding paper (Hazout et al. 1991). After building a triangular mesh between the geographical sites, the method consists of moving these locations at each iteration to reduce the overall differences between the geographic and genetic distances. The genetic similarity map, i.e. the final distorted map, allows the interpretation of the genetic diversity of a population set. We have applied this method to the study of Gm immunoglobulin allotypes of twenty-seven Amerindian groups from North and Central America. By a local weighted linear regression, we have reconstituted the distorted contour of America. This representation completes the observations of the sites during the map distortion. In this study, we have defined a large geographical factor in the genetic data (84% of the variability explained), related to a linguistic factor.

Gm haplotype distribution in Amerindians: relationship with geography and language.

A review is made of the Gm haplotype distribution in 60 groups of Eskimos, North, Central and South American Indians, totaling 22,808 individuals. Differences were observed in the shapes of the distribution of Gm*ag and the other markers. Nearly identical values for FST and average heterozygosities were obtained in the North+Central/South comparisons. North-South and Southwest/Northeast clinal differences were observed in the Americas using correspondence factorial analysis. The two haplotypes mainly responsible for these differences are Gm*axg and Gm*abOst. When the populations are classified by language groups, besides the recognized differences between Eskimos and Athabaskan (Na-Dene) speakers compared with Amerinds, others are found. For instance, Uto-Aztecan speakers of the United States and Mexico differ in Gm frequencies from the Nuclear Chibchan, Macro-Arawak, and Carib speakers of Central and South America. The notion of a homogeneous Amerind genetic pool does not conform with these and other results.

Evaluation of an immunoenzymatic assay detecting specific anti-Toxocara immunoglobulin E for diagnosis and posttreatment follow-up of human toxocariasis.

In order to complete the immunodiagnosis of human toxocaral disease, an immunoenzymatic assay with excretory-secretory antigens from Toxocara canis larvae was developed for the detection of specific immunoglobulin E (sIgE enzyme-linked immunosorbent assay [ELISA]). The specificity of the assay was evaluated in patients presenting with various allergic or helminthic diseases. The sensitivity was assessed in patients exhibiting clinical and biological symptoms indicative of toxocariasis, serodiagnosis of which was made by the Western blot (WB; immunoblot) procedure that used the same antigen as that used in the sIgE ELISA but that detected specific IgG. The value of the sIgE ELISA for posttreatment follow-up was tested in two groups of patients: one group was treated with diethylcarbamazine; the other group was not treated with DEC. Results showed that the specificity and sensitivity of the sIgE ELISA were moderate. Thus, the sIgE ELISA appeared to be insufficient for properly ensuring the serodiagnosis of toxocariasis when it is used alone. However, sIgE ELISA might be an interesting complementary method for the detection of specific IgG. It was the only assay that was found to be positive in sera from some hypereosinophilic patients. sIgE ELISA values decreased significantly among the patients treated with DEC, indicating that this test would be useful for posttreatment follow-up assessment.

Application of the western blotting procedure for the immunodiagnosis of human toxocariasis.

To improve the immunodiagnosis of human toxocaral disease, a sensitive and specific assay using the Western blotting procedure (WB) with excretory-secretory antigens from Toxocara canis larvae (TES) was developed and compared with the standard enzyme-linked immunosorbent assay method (TES-ELISA) using the same antigens. We tested groups of sera from laboratory animals or patients presenting with toxocariasis or other helminthic diseases and a group of sera from people dwelling in an area endemic for toxocariasis who exhibited hypereosinophilia. Statistically, the WB assay correlated well with TES-ELISA, but the former was more specific for banding patterns corresponding to low-molecular-weight fractions, thus avoiding problems of cross-reactivity with sera infected with other helminthic diseases.