Acta Tropica 116 (2010) 152–156 Contents lists available at ScienceDirect Acta Tropica journal homepage: www.elsevier.com/locate/actatropica Molecular differentiation of Angiostrongylus taxa (Nematoda: Angiostrongylidae) by cytochrome c oxidase subunit I (COI) gene sequences Praphathip Eamsobhana a,∗ , Phaik Eem Lim b,c , Gabriela Solano d , Hongman Zhang e , Xiaoxian Gan f , Hoi Sen Yong c a Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand b Institute of Ocean and Earth Science, University of Malaya, 50603 Kuala Lumpur, Malaysia c Institute of Biological Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia d Facultad de Microbiologia, Universidad de Costa Rica, San Jose, Apartado 2060, Costa Rica e Guangxi Zhuang Autonomous Region Center for Disease Control and Prevention, Nanning 530028, PR China f Institute of Parasitic Diseases, Zhejiang Academy of Medical Sciences, Hangzhou 310013, PR China article info Article history: Received 25 May 2010 Received in revised form 29 June 2010 Accepted 14 July 2010 Available online 21 July 2010 Keywords: Angiostrongylus cantonensis Angiostrongylus costaricensis Angiostrongylus malaysiensis Angiostrongylus vasorum Parastrongylus Molecular phylogeny Phylogeography abstract Nematodes of the genus Angiostrongylus are parasites of rodents and carnivores. They reside in the pul- monary or mesenteric arteries of their hosts. Two species are pathogenic in humans – Angiostrongylus cantonensis causes eosinophilic meningitis or meningoencephalitis, and Angiostrongylus costaricensis pro- duces abdominal angiostrongyliasis. In addition Angiostrongylus malaysiensis may have the potential of being pathogenic in humans. The mitochondrial gene cytochrome c oxidase subunit I (COI) of these Angiostrongylus species and three geographical isolates (China, Hawaii and Thailand) of A. cantonen- sis were studied by polymerase chain reaction amplification and DNA sequencing. COI sequences of A. cantonensis, A. costaricensis and Angiostrongylus vasorum in the GenBank were included for comparison. Phylogenetic analysis by maximum-likelihood (ML), maximum-parsimony (MP), neighbour-joining (NJ) and Bayesian inference (BI) produced similar tree topology except variation in the bootstrap support values. There were two major clades – (1) A. cantonensis and A. malaysiensis, and (2) A. costaricensis and A. vasorum. The three geographical isolates of A. cantonensis formed a clade with low to high bootstrap val- ues, and consisted of two subclades: (a) China and Hawaii isolates, and (b) monophyletic Thailand isolate. The individuals of each isolate formed a distinct cluster. In the second major clade, the Europe isolates of A. vasorum were distinctly different from the Brazil isolates. For A. costaricensis, the Costa Rica isolate was distinct from the Brazil isolate with an uncorrected (p) distance of 11.39%, indicating the possible occurrence of cryptic species. The present results indicate that COI sequences might be a useful marker for differentiating geographical isolates of A. cantonensis and in uncovering cryptic species. Efforts are being made to carry out an extensive collaborative study to cover a wide range of Angiostrongylus species and geographical isolates. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Nematodes of the genus Angiostrongylus Kamensky, 1905 are parasites of rodents and carnivores (Anderson, 2000). Under this classification, the component species are grouped into two sub- genera, i.e. Angiostrongylus and Parastrongylus (Drozdz, 1970; Anderson, 1978). These two subgenera however have been elevated by some authors (Chabaud, 1972; Ubelaker, 1986) as full genera, but this taxonomic treatment has not been generally accepted. Currently, 13 species are from rodent hosts and two from carni- vore hosts (Ubelaker, 1986; Costa et al., 2003; del Rosario Robles ∗ Corresponding author. Tel.: +66 (0) 24196468. E-mail address: sipes@mahidol.ac.th (P. Eamsobhana). et al., 2008). These nematodes reside in the pulmonary arteries of their hosts, except Angiostrongylus costaricensis Morera and Cés- pedes, 1971 and A. siamensis Ohbayahi, Kamiya and Bhaibulaya, 1979 which are found in the mesenteric arteries. Of the 15 Angiostrongylus species, only two are of public health importance, causing human angiostrongyliasis. Angiostrongy- lus cantonensis (Chen, 1935) is a primary cause of human eosinophilic meningitis or eosinophilic meningoencephalitis in Asia and the Pacific Islands (Eamsobhana and Tungtrongchitr, 2005; Eamsobhana, 2006). Its occurrence has now been reported in many countries worldwide (Eamsobhana, 2006; Cross and Chen, 2007; Foronda et al., 2010). Furthermore, the parasites of different geographical locality show different infectivity, sever- ity and pathogenicity in experimental hosts (Cross, 1979). The other species, A. costaricensis produces abdominal angiostrongylia- 0001-706X/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.actatropica.2010.07.005