Geographical identification of cadavers by human parasites

Comparative study between Helicobacter pylori and host human genetics in the Dominican Republic

Background

Helicobacter pylori, a bacterium that infects the human stomach, has high genetic diversity. Because its evolution is parallel to human, H. pylori is used as a tool to trace human migration. However, there are few studies about the relationship between phylogeography of H. pylori and its host human.

Methods

We examined both H. pylori DNA and the host mitochondrial DNA and Y-chromosome DNA obtained from a total 119 patients in the Dominican Republic, where human demography consists of various ancestries. DNA extracted from cultured H. pylori were analyzed by multi locus sequence typing. Mitochondrial DNA and Y-chromosome DNA were evaluated by haplogroup analyses.

Results

H. pylori strains were divided into 2 populations; 68 strains with African group (hpAfrica1) and 51 strains with European group (hpEurope). In Y-chromosomal haplogroup, European origin was dominant, whereas African origin was dominant both in H. pylori and in mtDNA haplogroup. These results supported the hypothesis that mother-to-child infection is predominant in H. pylori infection. The Amerindian type of mtDNA haplogroup was observed in 11.8% of the patients; however, Amerindian type (hspAmerind) of H. pylori was not observed. Although subpopulation type of most hpAfrica1 strains in Central America and South America were hybrid (hspWAfrica/hpEurope), most Dominican Republic hpAfrica1 strains were similar to those of African continent.

Conclusions

Genetic features of H. pylori, mtDNA, and Y haplogroups reflect the history of colonial migration and slave trade in the Dominican Republic. Discrepancy between H. pylori and the host human genotypes support the hypothesis that adaptability of hspAmerind H. pylori strains are weaker than hpEurope strains. H. pylori strains in the Dominican Republic seem to contain larger proportion of African ancestry compared to other American continent strains.

Usefulness of human herpes simplex virus type 1 genotyping for tracing the geographical origins of unidentified cadavers

Aim: We examined the possibility of tracing the origins of cadavers based on the geographic distribution of genotypes of the latent human herpes simplex virus type 1 (HSV-1). Materials & methods: PCR of the V1 region (667 bp) was performed using DNA from human trigeminal ganglia of 107 Japanese cadavers. The phylogenetic analysis was performed using 16 cadavers in Chiba district and 84 reference sequences in the world. Results: The HSV-1 DNA detection rate was 54.2% and it increased with age. This phylogenetic tree showed four large clusters, types I–IV (African, European, Asian and the mixed-type), and two subclusters (Japanese–Korean type and Japanese–Chinese type) in type III. Conclusion: HSV-1 genotype is possible to trace the geographical origin of unidentified cadavers.