Biochemical analysis of encapsulated and non-encapsulated species of Trichinella (Nematoda, Trichinellidae) from cold- and warm-blooded animals reveals a high genetic divergence in the genus.

Multilocus enzyme electrophoresis was used to analyse genetic variation in the genus Trichinella. Twenty-eight isolates belonging to eight species and six genotypes were analysed for 12 enzyme systems, producing 19 different phenotypes. According to Jaccard's similarity index, the isolates clustered into two main groups, specifically, encapsulated species/genotypes and non-encapsulated species/genotypes. Furthermore, the non-encapsulated species clustered into two other groups: the species infecting mammals and birds ( Trichinella pseudospiralis) and those infecting mammals and reptiles ( Trichinella papuaeand Trichinella zimbabwensis). The encapsulated species/genotypes, which only infect mammals, clustered into four main groups: the cosmopolitan species Trichinella spiralis, the species/genotypes of the temperate regions ( Trichinella britovi, Trichinella murrelli, Trichinella T8, and Trichinella T9), the species/genotype of the arctic region ( Trichinella nativa and Trichinella T6), and the equatorial species Trichinella nelsoni. These results are consistent with biological, epidemiological, and molecular data, which show a high genetic divergence in this genus.