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 (BacΔ111ORF2HEV), 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 BacΔ111ORF2HEV and mock cells were fixed and incubated with rabbit sera (1:500). Replication foci were visualized by reaction with amino-ethylcarbazole. Reverse-transcription–polymerase chain reaction (RT–PCR) 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.
Rotavirus and Hepatitis E virus infections in rabbits
OSTANELLO, FABIO;
2014
Abstract
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 (BacΔ111ORF2HEV), 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 BacΔ111ORF2HEV and mock cells were fixed and incubated with rabbit sera (1:500). Replication foci were visualized by reaction with amino-ethylcarbazole. Reverse-transcription–polymerase chain reaction (RT–PCR) 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
