Molecular characterization of Enterocytozoon bieneusi in cattle indicates that only some isolates have zoonotic potential

Abstract

In this study, 338 fecal samples were analyzed for Enterocytozoon bieneusi from cattle farms in Florida, Maryland, Michigan, New York, North Carolina, Pennsylvania, Virginia, and Portugal. The internal transcribed spacer region (392 bp) of the rRNA gene of E. bieneusi was amplified using a nested PCR protocol. Thirty-two E. bieneusi-PCR positive samples were sequenced. A high degree of genetic polymorphism, represented by five distinct genotypes (BEB1-BEB5), was found among the E. bieneusi isolates from cattle. Most of the isolates formed a distinct cluster consisting of only the four cattle genotypes, but six isolates of a genotype clustered together with E. bieneusi genotypes from humans and other domestic animals. Therefore, only some E. bieneusi isolates from cattle may be of public health importance.

Epidemiology ofEnterocytozoon bieneusiInfection in Humans

“…Genotypes I (also named BEB2/CEbE) and J (also named BEB1/CEbB, PtEb X), originally detected in cattle [25], were identified in both cow and human samples in this study. Both genotypes coinfected with other genotypes in all positive samples.…”

“…And recently, two groups of researchers reported the analysis of the GenBank E. bieneusi ITS sequence collection, using statistical methods, with the aim to obtain information about diversity, transmission, and evolution of this species [135, 136]. These studies have identified the presence of host-adapted E. bieneusi genotypes in a variety of domestic animals and wild mammals, as well as a large group of E. bieneusi genotypes that do not appear to have host specificity [24, 25, 135, 136]. These latter genotypes, considered zoonotic, are responsible for most human infections.…”

“…In contrast, Type IV (genotype K) was the only genotype found in a population in Cameroon [55]. Moreover, this genotype was also found in humans in other regions [18, 48, 56, 75, 76, 99, 111, 112] and in various animals [25–27, 122–125]. Type V was found only in one HIV-seropositive person.…”

Host Specificity and Source of Enterocytozoon bieneusi Genotypes in a Drinking Source Watershed

“…Over 100 E. bieneusi genotypes have been identified, belonging to at least six phylogenetically distinct genogroups (groups 1 to 5 and the socalled outlier in dogs) (15)(16)(17). Host adaptation is apparent among E. bieneusi genotypes (18)(19)(20), with almost all human isolates and some animal isolates belonging to genotypes in group 1 (3,4). Other genogroups contain mostly animal-adapted genotypes, including group 2 genotypes in cattle, group 3 genotypes in muskrats, group 4 genotypes in raccoons, group 5 genotypes in primates, and the outlier in dogs (15)(16)(17).…”

“…Determination of host adaptation of E. bieneusi genotypes, however, was based largely on ITS sequence characterizations of specimens from only a few domestic and wild animal species (18,19,24,25). Although the bovine-adapted nature of group 2 genotypes was confirmed in subsequent studies (26)(27)(28)(29), the host specificity of other genogroups remains to be determined.…”