Molecular Identification and Survey of Trichomonad Species in Pigs in Shanxi Province, North China

Abstract

Several trichomonad species have already been identified in pigs, and their pathogenic potential may not be ruled out. To date, however, no information is available regarding the prevalence of trichomonads in pigs in Shanxi Province, North China. In the present study, a total of 362 fecal samples collected from pigs in three representative counties (Qi, Jishan, and Shanyin) in this province were examined for Tetratrichomonas buttreyi, Tritrichomonas foetus, and Pentatrichomonas hominis using a nested polymerase chain reaction (PCR) with primers targeting the small subunit ribosomal RNA (SSU rRNA) gene. The overall prevalence of T. buttreyi was 49.72%, and region and age were found to be significantly associated with T. buttreyi infection, respectively. Only one pig fecal sample from Qi County was found to be positive for T. foetus, and all samples were negative for P. hominis. Molecular evolutionary analysis revealed that some T. buttreyi isolates showed complete genetic identity with those reported previously, and some T. buttreyi isolates and one T. foetus isolate showed minor allelic variations compared with those reported previously. This is the report of the molecular epidemiology of T. foetus and T. buttreyi in pigs in Shanxi Province, North China. These findings not only enrich the knowledge on the distribution of these trichomonad species in pigs in China but also provide baseline information for planning future research and control strategies.

Keywords: Shanxi Province; pigs; prevalence; sequence analysis; trichomonads.

Figure 1

Agarose gel electrophoresis of the PCR products. (A) Lane M: 1000 bp DNA ladder; lane PC: positive control; lane NC: negative control; lane 1–3: nested PCR amplification with primers specific for a 452-bp segment of the T. foetus SSU rRNA gene using the genomic DNA extracted from each pig fecal sample as a template. (B) Lane M: 1000 bp DNA ladder; lane PC: positive control; lane NC: negative control; lane 1–5: nested PCR amplification with primers specific for a 623-bp segment of the T. buttreyi SSU rRNA gene using the genomic DNA extracted from each pig fecal sample as a template.

Figure 2

Alignment of the SSU rRNA sequences of T. buttreyi isolates obtained in the present study (PP256574–PP256581) and that of a T. buttreyi isolate from a previous study (KM205212). Dots represent nucleotides identical to the consensus sequence, while dashes indicate base deletion.

Figure 3

Phylogenetic relationships among trichomonad isolates inferred with a neighbor-joining analysis based on the nucleotide sequences of the SSU rRNA gene, rooted using Barbulanympha ufalula as an outgroup. The SSU rRNA sequences generated in the present study are indicated by black triangles.