Performance of pre-RT-qPCR treatments to discriminate infectious human rotaviruses and noroviruses from heat-inactivated viruses: applications of PMA/PMAxx, benzonase and RNase.

AIMS: Detection/Quantification of RNA viruses is mostly done by reverse-transcriptase (RT)-(q)PCR, but it does not distinguish between infectious and noninfectious viruses. Our aim was to test, how different pretreatments before RT-qPCR could eliminate positivity originated from external nucleic acids or genomes of damaged particles. METHODS AND RESULTS: Heat-inactivated (80°C for 10 min) rotavirus Wa strain and faecal samples containing rotavirus or norovirus were treated with PMA/PMAxx, benzonase or crude extract RNase prior to RT-qPCR. PMA/PMAxx pretreatments were not consistently efficient for RV, although they seemed to work to some extent for heat-inactivated norovirus. Benzonase and RNase provided consistently 2·2-2·8 log10 reductions in the titre of faecal rotavirus. CONCLUSIONS: All pretreatments need to be further validated for each virus separately, taking into account sample matrix and inactivation conditions. Although none of the pretreatments could completely render inactivated viruses undetectable, RNase worked most consistently for both rota- and norovirus. SIGNIFICANCE AND IMPACT OF THE STUDY: This study sheds light on capacity of the most common pre-RT-qPCR treatments to eliminate damaged, noninfectious rotaviruses and noroviruses after thermal treatment. To our knowledge, this is the first time, when benzonase has been used in this context.

Hepatitis E Virus Antibodies in Finnish Veterinarians.

We investigated hepatitis E virus (HEV) infections in Finnish veterinarians engaged in different practice specialties and evaluated the effect of different background factors on HEV exposure by examining total HEV antibodies in samples collected from the participants of the 2009 National Veterinary Congress in Helsinki, Finland. Finnish veterinarians commonly have total HEV antibodies with seroprevalence of 10.2%. Of the non-veterinarians, 5.8% were seropositive. Increasing age was associated with HEV seropositivity, and, surprisingly, the highest HEV seroprevalence (17.8%) among veterinarians was detected among small animal practitioners. Although no positive correlation between swine contacts and HEV seropositivity was found, 22.7% of veterinarians who had had needle stick by a needle that had previously been injected into a pig versus 9.0% of those who had not were seropositive, even though the finding was statistically non-significant (P = 0.07). Our results suggest that, although contact with swine is a known risk factor for HEV infection, the sources of HEV infections are probably numerous, including travelling abroad and possibly also other reservoirs of HEV than pigs.

A longitudinal study revealing hepatitis E virus infection and transmission at a swine test station.

Hepatitis E virus (HEV) is a zoonotic agent that causes acute hepatitis in humans, and infects several animal species, most importantly swine. In the current study, that presents the first evidence of HEV infections in pigs in Finland, genetic divergence and transmission of HEV was investigated among pigs at a swine test station at two occasions. In 2007, HEV RNA was found in 25% of pens, and 35% of 2-3 month-old pigs at the station. Three different isolates, comprising 13 sequences of HEV genotype 3 e that were imported from different farms were detected. In 2010, 39% of pigs were HEV RNA positive on weeks 1, 3, or 5 of a 3-month follow-up, and 11 sequences, all representing one of the isolates that was also present in 2007, were detected. The isolate was considered to be either re-introduced to, or to persist at the station, and it was transmitted between the pigs. The study sheds light on the rate and time of HEV transmission in swine, and describes the epidemiologic variability of HEV isolates over time.