Zoonotic viruses are thought to be the highest risk of epidemic
diseases for next years. Among others, these also include rotavirus,
agent of gastroenteritis in man and animals and hepatitis E virus
(HEV), which causes acute hepatitis in humans and infect domestic
and wild animals.
Group A rotaviruses (RVA) infection is preferentially species-specific,
heterologous rotavirus infections may also occur, including animal-tohuman
virus transmission.
Recently, a human RVA of rabbit origin was described in a child with
gastroenteritis, and a bovine-like RVA was isolated from a laboratory
rabbit . Hepatitis E is an emerging disease now recognized to be a zoonosis.
Swine, wild boar, deer and rabbit are considered reservoirs of the
zoonotic HEV genotypes 3 and 4. Recently HEV was detected in both
farmed and wild rabbits in several areas of China, USA and France. The
prevalence of serum antibodies against HEV ranges between 7% and 57% in young animals.
Several evidences support a risk of zoonotic transmission of HEV from
rabbits to humans, including experimental infection of non-human
primates and swine with rabbit HEV and detection of HEV closely
related to rabbit HEV in a man. HEV and RVA infections were studied in 21 farmed and 121 pet rabbits
in Italy. Virus infection was investigated by serological analysis in sera
and by detection of RNA in fecal samples.
During 2013, a total of 121 rabbits attending veterinary examination
were enrolled in this study. Sera and feces were collected from the
same animals (except 7 fecal samples). Seventy-seven pets were
asymptomatic, most others were affected by different pathologies.
Between October 2013 and February 2014, 21 samples were
collected from stud-mare rabbits affected by reproductive failure.
Western blotting (WB). The capsid protein of an Italian gt3 swine
HEV strain expressed in Sf9 cells from a recombinant baculovirus
(Bac\u394111ORF2HEV), the purified SA11 RV and crude extract of mock
Sf9 (negative control) were subjected to WB. Sera were diluted 1:100.
Immunocytochemistry. Sf9 cells infected with Bac\u394111ORF2HEV
and mock cells were fixed and incubated with rabbit sera (1:500).
Replication foci were visualized by reaction with amino-ethylcarbazole.
Reverse-transcription\u2013polymerase chain reaction (RT\u2013PCR) and DNA
sequencing. RNA was extracted using Qiagen RNA-Easy-Mini kit. For both viruses, RT-PCRs were performed using the OneStep RT-PCR kit
(Qiagen). For Rotavirus the NSP5 segment was amplified. For HEV an RT-PCR and a nested-PCR were conducted, amplifying a 300 bp
ORF2 fragment.
None of the 135 fecal samples, (114 pets and 21 farmed rabbits),
showed presence of HEV genome. IgG against HEV were detected
in 4 of 121 pet rabbits tested. Two seropositive animals were
asymptomatic, one was affected by rhinitis. Rabbits showed no clinical
signs of RVA infection. Twelve out of 52 sera recognized specific RVA
proteins. Twelve samples resulted positive in RT-PCR, one was
confirmed through sequence analyses. One animal was positive for
both RVA and HEV IgG.
None of the feces (farmed or pet rabbits) were positive for HEV
genome. The seroprevalence in pet rabbits was 3.3% in this study,
markedly lower than observed in farmed animals (36% in China
and 55% in USA). The lower seroprevalence in our study might
be explained with the different animal population; pets living in
households have no contact with other animals, which reduces
the possible HEV transmission through the fecal-oral route.
The study of naturally occurring heterologous rotaviruses
may help understand how rotavirus cross the host-species
barrier and investigate the molecular determinants that
control rotavirus host-species specificity and pathogenicity.
Contact between pet rabbits and their owners, e.g. changing the
litter, might favor animal-to-human transmission; similar risks occur
in persons with occupational exposure to farmed rabbits. Possible
foodborne transmission of rabbit HEV should also be evaluated
