Incursion of Schmallenberg virus into Great Britain in 2011 and emergence of variant sequences in 2016.

Schmallenberg virus (SBV) is a vector-borne orthobunyavirus in the family Bunyaviridae, first identified in Germany before rapidly spreading throughout Europe. To investigate the events surrounding the incursion of this virus into Great Britain (GB) and its subsequent spread, archived sheep serum samples from an unrelated field survey in 2011 were analysed for the presence of SBV specific antibodies, to determine the earliest date of seroconversion. This serological study, along with analysis of the spatial spread of the sources of samples submitted for SBV analysis after January 2012, suggests that SBV entered GB on more than one occasion and in more than one location. Phylogenetic analysis of SBV sequences from 2012 ovine samples, from a variety of counties and dates, demonstrated a non-linear evolution of the virus, i.e. there was no distinct clustering between host species, geographical locations or during the outbreak. This also supports the notion of multiple viruses entering GB, rather than a single virus incursion. Premature termination signals were present in several non-structural putative protein sequences. One SBV sequence exhibited large deletions in the M segment of the genome. After the first outbreak in 2011-2012, interest in SBV in GB waned and continuous surveillance was not upheld. The re-emergence of SBV in 2016 has raised renewed concern and ended speculation that SBV might have been eradicated permanently from GB. When SBV sequences from 2012 were compared with those from the re-emergence in 2016-2017, a second distinct clade of SBV was identified that separates recent strains from those observed during the first outbreak.

Re-emergence of a genetic outlier strain of equine arteritis virus: Impact on phylogeny.

Equine arteritis virus (EAV) is the causative agent of equine viral arteritis (EVA), a respiratory and reproductive disease of equids, which is notifiable in some countries including the Great Britain (GB) and to the OIE. Herein, we present the case of a persistently infected stallion and the phylogenetic tracing of the virus strain isolated. Discussing EAV occurrence and phylogenetic analysis we review features, which may aid to harmonise and enhance the classification of EAV.

Genome sequence analysis of 10 Dutch porcine circovirus type 2 (PCV-2) isolates from a PMWS case-control study.

The factors responsible for the emergence of post-weaning multisystemic wasting syndrome (PMWS) as an epidemic disease with significant impact upon the pig industry are not all known. Porcine circovirus type 2 (PCV-2) has been shown to be necessary but not sufficient for the expression of PMWS. Retrospective serological and molecular surveys have shown that PCV-2 was widespread and was maintained with only occasional reports of sporadic PMWS in the 30 year period prior to the recent emergence of the epidemic form of the syndrome. However, the recent spread of the disease in Europe and elsewhere has pointed to the transmission of a novel pathogen. One explanation to reconcile this paradox is that PWMS is caused by a unique PCV-2 variant that is being spread through pig populations. To test this hypothesis, complete genomes (1767 bp) of 10 Dutch PCV-2 isolates from 4 PMWS affected premises and 6 farms without PMWS were sequenced. Phylogenetic analysis showed that these sequences were grouped together although they differed on 77 nucleotide positions relative to each other (95.6-100% identity between the 10 isolates). None of these nucleotide changes identified impacted upon transcriptional elements or other important recognised features of the genome of the PCV-2. Amino acid changes were recorded on 4 positions in ORF1 and on 16 positions in ORF2 but, importantly, no consistent pattern was evident between PCV-2 isolates from affected and control pigs. These data provide further evidence to suggest that factor(s) in addition to PCV-2 are necessary in the development of PMWS.

Evidence for the presence of hepatitis E virus in pigs in the United Kingdom.

Samples of serum, tissue and faeces from two pig herds in England were examined for hepatitis E virus by reverse-transcriptase PCR (RT-PCR), and a virus strain from each herd was partially sequenced. Eleven of 42 faecal samples and 16 of 21 tissue samples from two pigs were positive for the virus by RT-PCR. Analysis of two unique but closely related nucleotide sequences obtained from the two herds showed that the viruses clustered in genotype III (6) with a human strain of the virus from an autochthonously acquired case of acute hepatitis in the UK. An ELISA based on recombinant open reading frame 2 (ORF-2) was used to detect antibodies to hepatitis E virus in 256 pig sera from the UK; 85.5 per cent of the samples were positive, compared with 58 per cent of similar samples from Swedish pigs and 23.5 per cent of samples from Dutch pigs.

Systematic assessment of the impact of adenovirus infection on a captive reintroduction project for red squirrels (Sciurus vulgaris).

PCR was used to amplify adenoviral DNA, and transmission electron microscopy (TEM) to detect adenovirus particles in tissue and intestinal content samples from red squirrels (Sciurus vulgaris) associated with a reintroduction study on Anglesey (North Wales), from other populations on the island and from stock held at the Welsh Mountain Zoo, 38 km to the east. Samples were collected during the routine surveillance postmortem examinations of all 60 red squirrels with carcases retrieved in a suitable condition between 2004 and 2010, including 29 captive and 31 free-living animals. Following significant clusters of mortality in captive red squirrels, adenovirus was identified retrospectively in faecal material from 12 of 13 (92 per cent) examined carcases from squirrels captive on Anglesey, and 14 of 16 (88 per cent) from the Welsh Mountain Zoo. Virus was identified in 13 of 31 (42 per cent) free-living wild animals, with evidence of both subclinical and clinically significant enteric adenoviral infections in wild squirrels. Without ancillary PCR and TEM testing, the extent of adenovirus infection in such populations would have been underestimated. Screening protocols that include examinations for adenovirus should, therefore, be part of the routine biosecurity measures protecting reintroduction or captive breeding programmes for red squirrels.

Detection and genetic typing of type 2 porcine circoviruses in archived pig tissues from the UK.

Porcine circovirus 2 (PCV-2) is implicated as the causative agent of post-weaning multisystemic wasting syndrome (PMWS) and is also associated with porcine dermatitis and nephropathy syndrome (PDNS). The recent emergence of epidemic PMWS in the United Kingdom was predated by sporadic cases of PDNS dating back to the early 1980's. The aim of this study was to investigate whether PCV-2 DNA was present in archival tissues, and if so, to investigate the relatedness of these viruses with contemporary strains of PCV-2. DNA extracted from paraffin wax-embedded tissue blocks ( n = 68), was subjected to a TaqMan polymerase chain reaction (PCR) targeting a fragment of ORF1 of PCV-2. Positive results were obtained from 41% (9/22), 31% (4/13) and 32% (8/25) of submissions from the 1990's, 1980's and 1970's respectively. The presence of PCV-2 antigen in some of these tissues was confirmed by immunohistochemistry (IHC). A PCR targeting ORF2 was used to obtain sequence data for phylogenetic analysis. Sequences from 5 archival tissues were unique but showed high genetic identity to PCV-2 sequence obtained from a 2000 PDNS case. These data demonstrate that similar isolates of PCV-2 have been present in the UK pig population for more than 30 years.