Molecular Characterization of Various Trichomonad Species Isolated from Humans and Related Mammals in Indonesia

Trichomonad species inhabit a variety of vertebrate hosts; however, their potential zoonotic transmission has not been clearly addressed, especially with regard to human infection. Twenty-one strains of trichomonads isolated from humans (5 isolates), pigs (6 isolates), rodents (6 isolates), a water buffalo (1 isolate), a cow (1 isolate), a goat (1 isolate), and a dog (1 isolate) were collected in Indonesia and molecularly characterized. The DNA sequences of the partial 18S small subunit ribosomal RNA (rRNA) gene or 5.8S rRNA gene locus with its flanking regions (internal transcribed spacer region, ITS1 and ITS2) were identified in various trichomonads; Simplicimonas sp., Hexamastix mitis, and Hypotrichomonas sp. from rodents, and Tetratrichomonas sp. and Trichomonas sp. from pigs. All of these species were not detected in humans, whereas Pentatrichomonas hominis was identified in humans, pigs, the dog, the water buffalo, the cow, and the goat. Even when using the high-resolution gene locus of the ITS regions, all P. hominis strains were genetically identical; thus zoonotic transmission between humans and these closely related mammals may be occurring in the area investigated. The detection of Simplicimonas sp. in rodents (Rattus exulans) and P. hominis in water buffalo in this study revealed newly recognized host adaptations and suggested the existence of remaining unrevealed ranges of hosts in the trichomonad species.

Genetic Characterization of Clinical Acanthamoeba Isolates from Japan using Nuclear and Mitochondrial Small Subunit Ribosomal RNA

Because of an increased number of Acanthamoeba keratitis (AK) along with associated disease burdens, medical professionals have become more aware of this pathogen in recent years. In this study, by analyzing both the nuclear 18S small subunit ribosomal RNA (18S rRNA) and mitochondrial 16S rRNA gene loci, 27 clinical Acanthamoeba strains that caused AK in Japan were classified into 3 genotypes, T3 (3 strains), T4 (23 strains), and T5 (one strain). Most haplotypes were identical to the reference haplotypes reported from all over the world, and thus no specificity of the haplotype distribution in Japan was found. The T4 sub-genotype analysis using the 16S rRNA gene locus also revealed a clear sub-conformation within the T4 cluster, and lead to the recognition of a new sub-genotype T4i, in addition to the previously reported sub-genotypes T4a-T4h. Furthermore, 9 out of 23 strains in the T4 genotype were identified to a specific haplotype (AF479533), which seems to be a causal haplotype of AK. While heterozygous nuclear haplotypes were observed from 2 strains, the mitochondrial haplotypes were homozygous as T4 genotype in the both strains, and suggested a possibility of nuclear hybridization (mating reproduction) between different strains in Acanthamoeba. The nuclear 18S rRNA gene and mitochondrial 16S rRNA gene loci of Acanthamoeba spp. possess different unique characteristics usable for the genotyping analyses, and those specific features could contribute to the establishment of molecular taxonomy for the species complex of Acanthamoeba.