Mutation scanning-coupled analysis of haplotypic variability in mitochondrial DNA regions reveals low gene flow between human and porcineAscaris in endemic regions of China

Abstract

Haplotypic variation within and among the Ascaris populations representing six provinces in China was investigated. Mitochondrial DNA regions in the cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes were amplified by PCR from total genomic DNA samples (n > 720) from Ascaris individuals from humans and pigs, and subjected to mutation scanning and subsequent selective sequencing. For the cox1, ten different electrophoretic profiles were recorded for human Ascaris, and the same number for pig Ascaris, one of them being common to both host species. For the nad1, 11 different profiles were detected for human Ascaris, and 15 for pig Ascaris. Having defined all haplotypes (20 for pcox1 and 26 for pnad1) by sequencing, their frequencies were estimated in each of the two host species and each of the six provinces. For each mitochondrial region, the frequency of the different haplotypes varied considerably, depending on host species and geographical origin. Analysis of the sequence data (representing all haplotypes for each mitochondrial locus) by F-statistics indicated restricted gene flow between human Ascaris and pig Ascaris, and supported the conclusions from previous molecular epidemiological investigations that pigs are not a significant source of Ascaris infection in humans in endemic regions.

Paleoparasitological report on Ascaris aDNA from an ancient East Asian sample

“…Therefore, the aDNA analysis reported here falls short of confirming the Ascaris aDNA as A. lumbricoides. Many currently available nuclear or mitochondrial targets are not satisfactory for differentiating A. lumbricoides from A. suum (Anderson 2001, Peng et al 2005, Leles et al 2010, which stems from the close relationship between the two species (Barry & O' Rourke 1967, Crompton 1989, Zhu et al 1999, Leles et al 2010. This is again evident in our study because the differentiation between these two species was not achieved after genetic analysis.…”

“…In the case of ancient Ascaris spp, one of the most widespread parasitic infections in humans (Loreille & Bouchet 2003), PCR-based analyses have been performed and reported by Loreille et al (2001) and Leles et al (2008). However, even though Ascaris spp have been identified by molecular studies of archaeological specimens, their genetic diagnosis has not been studied in greater detail so far (Anderson 2001, Peng et al 2005, Leles et al 2010. Moreover, since most aDNA studies on Ascaris have been limited in their geographical distribution to Europe and South America, it is desirable to secure Ascaris aDNA data from a much wider geographic and temporal range.…”

Assessing the zoonotic potential ofAscaris suumandTrichuris suis: looking to the future from an analysis of the past

“…Application of a similar molecular approach to 115 sympatric worms obtained from humans and pigs in China (Peng et al, 1998) led to an analogous conclusion. This was later confirmed by the use of singlestrand conformation polymorphism (SSCP) to detect nucleotide variation in the internal transcribed spacer (ITS) region and mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes of 486 and 329 worms from humans and pigs, respectively, collected from six provinces in China (Peng et al, 2003(Peng et al, , 2005. Even though no fixed genetic differences were identified (i.e.…”

Helminth parasites in pigs: New challenges in pig production and current research highlights

“…Sprent, 1952;Ansel and Thibaut, 1973;Maung, 1973;Kennedy et al, 1987;Hawley and Peanasky, 1992) but all with limited success. More recently the application of different DNA-based methods on sympatric Ascaris populations in Guatemala, China, and Uganda suggests that there is no or limited gene flow between worms infecting humans and pigs (Anderson and Jaenike, 1997;Peng et al, 2005;Nejsum et al, 2010) implying that there are two different populations (species). In contrast, Criscione et al (2007) identified 4 and 7% of sympatric worms as being hybrids suggesting that cross-infections take place in areas where humans and pigs live in close proximity.…”