17 research outputs found
Detection of Multiple Genotypes of Calicivirus Infection in Asymptomatic Swine in Taiwan
Noroviruses (NoVs) and sapoviruses (SaVs) of the family Caliciviridae are
emerging enteric pathogens in humans and animals. Recent detection of genogroup
II norovirus (GII NoV) RNA from swine raises public health concerns
about zoonotic transmission of porcine NoVs to humans. However, few papers
reported genotype distributions and epidemiological features in swine farms
and their genetic relationship to human strains, which was the objective of our
study. This study investigated the epidemiological features and genotypes of
caliciviruses in swine farms using 533 pig faecal samples from six farms in central
and southern Taiwan, tested for viral RNA using RT-PCR targeting the conserved
polymerase gene. NoVs and SaVs were detected with a positive rate of
7.1% and 0.6%, respectively. To confirm the positive rate of NoVs, 255 pig
faecal samples from two farms in central Taiwan were tested with primer pairs
targeting the partial capsid gene of GII, and 32.3% of the positive rate was
found. Furthermore, the results from the capsid region suggested a higher positive
rate of 41.7% in winter than 26.4% in summer with statistical significance
(P < 0.05). Sequence analysis showed 29 strains belonging to GII.4 (human)
and nine strains belonging to GII.11 (swine) identified based on the partial
polymerase gene. Additional genotypes clustered with GII.2 (human) and GII.18
(swine) were also characterized based on the partial capsid gene. SaVs detected
in porcine faecal samples belonged to genogroup III (GIII), which clustered with
the PEC-Cowden strain. Our study demonstrated the presence of multiple genotypes
of both human and porcine NoVs infecting swine of various ages asymptomatically.
Although the zoonotic potential of detected human NoVs in swine
was not conclusive owing to the lack of local human faecal samples, our study
revealed the importance of monitoring emerging strains in swine to mitigate the
potential impact of recombinant NoVs infecting the human population