Abstract
Viruses closely related to Norwalk-like viruses (NLVs) were recently found in stored stool samples from two calves (United Kingdom and Germany) and four pigs (Japan), sparking discussions about the potential for zoonotic transmission. To investigate if NLVs are commonly present in farm animals, pooled stool samples from 100 pig farms, 48 chicken farms, 43 dairy cow herds, and 75 veal calf farms from the Netherlands were assayed by reverse transcription- polymerase chain reaction amplification, using primers specific for the detection of NLVs from humans. NLV RNA was detected in 33 (44%) of the specimens from veal calf farms and two (2%) specimens from pig farms. Our data show that NLV infections until recently thought to be restricted to humans occur often in calves and sometimes in pigs. While zoonotic transmission has not been proven, these findings suggest that calves and pigs may be reservoir hosts of NLVs.
Highlights
Caliciviruses infect animals and humans [1]
We studied enteric caliciviruses in recently collected fecal samples from cattle, chicken, and swine in the Netherlands by using polymerase chain reaction (PCR) assays specific for Norwalk-like viruses (NLVs) found in humans
The NLV-reverse transcription (RT)-PCR was negative for all pooled specimens from 43 dairy herds and 48 chicken farms
Summary
Caliciviruses infect animals and humans [1]. Within the family Caliciviridae, four genera have been distinguished: vesivirus, lagovirus, Norwalk-like viruses (NLV), and Sapporo-like viruses (SLV) [2]. The genera vesivirus and lagovirus contain a broad range of animal caliciviruses, but viruses in the NLV and SLV genera until recently have been found only in humans. The human caliciviruses separate into at least three genetic clusters, called genogroups (GG), i.e., GGI and GGII NLV and the GGIII SLV [6] Each of these genogroups comprises genomically and antigenically diverse strains [7,8]. Hypotheses for the mechanisms behind the emergence of epidemic types range from large-scale foodborne transmission of a single strain to introduction from a nonhuman reservoir An indication for the latter was a recent report from Japan of the finding of NLV-like sequences in stool specimens from pigs [12]. We analyzed (by sequence analysis) the genetic variation of detected calicivirus strains and compared it with that of prototype GGI and GGII NLV strains
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