Sequence variation in the B1 gene among Toxoplasma gondii isolates from swine and cats in Italy.

The evaluation of the genetic variations of Toxoplasma gondii among isolates of a wide variety of animal hosts can provide significant information for better understanding the epidemiology and population structure of the parasite in different geographical areas. The aim of this study was to provide information on T. gondii genetic diversity in host species living in central Italy, which could act as a potential source of human infection. Seventy-seven feline faecal samples, and 36 and 20 diaphragm pillar tissue samples from pigs and wild boars were collected in Umbria (central Italy). The samples were tested by a nested-PCR protocol amplifying an informative region within the B1 gene, a multi-copy genetic target, showing a good rate of variability. Thirty-six specimens (27.07%) belonging to 10 pigs, 13 wild boars and 13 cats, tested positive to the B1 nested-PCR screening. Of these, 23 good quality sequences (8 from wild boars, 5 from pigs, and 10 from cats) were analyzed. A comparison of the B1 DNA sequences showed that a single homogeneous nucleotide substitution (C/T) was present at position 31 in the isolates from pigs and wild boars compared with the sampled cats and other hosts (including humans) available in GenBank™. The present results suggest the existence of a T. gondii genetic diversity for swine host species, based on a SNP (C/T) of the B1 gene. Further studies are needed to draw more solid conclusions on the discriminatory power of the B1 target by collecting more swine samples from much broader geographical areas.