Jeerapun Worapong

Blastocystis Isolates from a Pig and a Horse Are Closely Related to Blastocystis hominis

ABSTRACT Blastocystis has a widespread distribution in a variety of animals, which is a potential source of infection for humans. However, the contribution of zoonotic transmission remains unclear due to the absence of molecular proof of these organisms being identical to those found in humans. We report herein the similar subgroup of Blastocystis isolates from humans, pigs, and a horse using a restriction fragment length polymorphism (RFLP) analysis of partial small-subunit ribosomal DNA (ssu rDNA). Additionally, sequence and phylogenic analysis of partial ssu rDNA of Blastocystis from a human, a pig, and a horse sharing a common subgroup shows that Blastocystis isolates from a pig and a horse were monophyletic and closely related to B. hominis, with 92 to 94% identity. These results suggest the possibility of zoonotic potential of Blastocystis.

A suspected new species of Leishmania, the causative agent of visceral leishmaniasis in a Thai patient.

A suspected new species of Leishmania is described as the causative agent of the third reported case of autochthonous visceral leishmaniasis in a Thai man living in Southern Thailand. The results of PCR-restriction fragment length polymorphism and sequence analysis of the internal transcribed spacer 1 of ssrRNA and the mini-exon genes were different from those of previously reported Leishmania species. A direct agglutination test (DAT) revealed that antibody against Leishmania infection was detected in nine domestic cats. No potential vectors could be identified. A large-scale epidemiological survey of leishmaniasis should be urgently conducted since visceral leishmaniasis is considered an emerging disease of public health concern in Thailand.

Identification of genotypes of Enterocytozoon bieneusi from stool samples from human immunodeficiency virus-infected patients in Thailand

ABSTRACT We identified genotypes of Enterocytozoon bieneusi from 33 stool samples of Thai human immunodeficiency virus (HIV)-infected adult patients. Genotype D was identified at the highest frequency (36.4%), while genotype E was the second most common (15.1%). Genotypes O and PigEBITS 7, previously found only in pigs, were observed in Thai HIV-infected patients. Phylogenetic analysis supported a zoonotic nature for E. bieneusi.

Genotypic Study of Pneumocystis jirovecii in Human Immunodeficiency Virus-Positive Patients in Thailand

ABSTRACT Pneumocystis jirovecii is one of the common opportunistic infections in human immunodeficiency virus (HIV)-infected patients in Thailand. Information regarding genotypic and epidemiological of this organism in Thai patients is not available. We analyzed the genotypes of 28 P. jirovecii-positive specimens from bronchoalveolar lavage and sputum samples from HIV-infected Thai patients based on nucleotide variations of the internal transcribed spacer regions 1 and 2 of the rRNA gene. Thirteen genotypes were the same as previously reported outside Thailand. Ten genotypes, which included Bp, Er, Eq, Ic, Ir, Ip, Rc, Rp, Qb, and Qq, were new. Ir and Rp were unique and dominant types observed in HIV-infected Thai patients. Thirteen specimens (46.4%) were infected with a single type of P. jirovecii, and fifteen (53.6%) were mixed infections. These differences may be used as genotypic markers for studying the epidemiology and transmission of P. jirovecii in the Thai population.

Biocontrol of a root rot of kale by Muscodor albus strain MFC2

Pythium ultimum is an oomycetous root rot pathogen that causes significant crop production losses on many crops including kale (Brassica oleracea), an economically important vegetable in Thailand. An endophytic fungus from Thailand designated Muscodor albus MFC2 controlled P. ultimum both in vitro and on kale seedlings grown under outdoor conditions via the production of volatile antibiotics. Ten-day old M. albus MFC2 PDA cultures killed P. ultimum in vitro. Thoroughly mixing three PDA plates of 10-day old M. albus MFC2 into a 500 g mixture of commercial soil and field soil did not adversely affect kale seed germination. The same amount of M. albus MFC2 could restore seedling emergence in P. ultimum inoculated soil to a level close to that of a non-infested control. In addition, M. albus MFC2 did not cause any disease symptoms, but rather seemed to promote the growth of kale in the presence or absence of P. ultimum for up to eight weeks after planting.

An in vitro detached leaf assay for pre-screening resistance to anthracnose disease in cassava (Manihot esculenta Crantz).

Cassava anthracnose disease (CAD), caused by Colletotrichum gloeosporioides f. sp. manihotis is one of the most important fungal infections that affects cassava yield in many countries especially in Africa and including Thailand. In this study, a rapid screening method to identify cassava varieties that are resistant to CAD based on a detached leaf assay was developed. Three different varieties of cassava commonly grown in Thailand, Hanatee, Huay Bong 60 and Kasetsart 50 were used. Agar plugs (0.8 cm diameter) with mycelia of C. gloeosporioides f. sp. manihotis were applied to the centre of the middle lobe of the cassava leaves, while sterile potato dextrose agar plugs were used as controls. Lesions on the inoculated samples were measured on the fourth day after inoculation. The size of the lesions on each variety was compared using ANOVA and the results revealed that Huay Bong 60 showed the highest resistance to CAD whereas Hanatee was the most susceptible variety. The screening method developed in this study can be undertaken within a short time and without contamination of the pathogen into the environment. This methodology will be useful for identification of cassava varieties with resistance to CAD.

Analysis of mitochondrial COI sequences of the Diachasmimorpha longicaudata (Hymenoptera: Braconidae) species complex in Thailand

Diachasmimorpha longicaudata is an Opiinae parasitoid used to control tephritid fruit flies, which cause tremendous economic losses of fruits worldwide. In Thailand, D. longicaudata is classified as three sibling species, DLA, DLB and DLBB, based on the morphological and biological species concepts but their genetic variation has not been studied. Therefore, we investigated the genetic differentiation of the mitochondrial COI gene to clarify the ambiguous taxonomy of this species complex. The 603‐bp COI region was sequenced from laboratory‐bred colonies and field‐collected specimens from seven locations representing five geographical regions in Thailand. DLA was associated with the host Bactrocera correcta while DLB and DLBB were associated with Bactrocera dorsalis. The interspecific nucleotide differences of COI sequences among the three groups ranged from 6.70% to 7.62% (Kimura 2‐parameter distance), which adequately separates species complexes within the order Hymenoptera and supports the current sibling species classification. The neighbor joining, maximum likelihood and consensus Bayesian phylogenetic trees constructed from COI sequences revealed that the three sibling species of laboratory and field‐collected D. longicaudata are monophyletic with 100% support. The high genetic variation and molecular phylogeny of the COI sequences were shown to discriminate between the D. longicaudata species examined in this study.