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Sheep infected with Anaplasma phagocytophilum, the causative agent of tick-borne fever (TBF), develop humoral immune responses 7–14 days after infection. Those individuals that survive acute TBF develop persistent infection, which may last for several months or even for life. The persistence of infection and recurrent bacteraemia is thought to be due to p44-mediated antigenic variation. The present study mapped linear B-cell epitopes within the hypervariable region (HVR) of the surface membrane protein P44 and investigated whether the development of antibodies against B cell epitopes within the HVR was preceded by the expression of p44 variants. Serum samples obtained from five sheep infected with the Old Sourhope strain of A. phagocytophilum (AP-OS) were used to detect antibody reactivity against 20-mer overlapping synthetic peptides spanning the HVR of two p44 variants which were expressed during primary bacteraemia and 3 variants expressed during secondary bacteraemia. The results showed that all five p44 variants of AP-OS have dominant B-cell epitopes residing mainly in the 3rd and 7th of the 10–11 peptides mapping each HVR. Antibody reactivity against peptides of the HVR of all the variants was characterised by a gradual rise, reaching peak levels in samples obtained 24 days post-inoculation (dpi) followed by a gradual decline. Anamnestic responses to whole cell antigens and to some of the dominant antigenic epitopes were detected in some of the animals, which were monitored for 52 weeks.

In order to determine the prevalence of canine enteric coronavirus (CECoV) in the general dog population, faecal samples were obtained in a cross-sectional study of 249 dogs presenting for any reason at veterinary practices randomly selected from across the UK. Demographic and clinical data was obtained for each of the samples, including signalment, number of dogs in the household, reason for visiting the practice, and any recent history of diarrhoea. The samples were tested by RT-PCR for the presence of both type I and type II CECoV. Seven samples were positive (three from dogs in the same household), a prevalence of 2.8% (95% confidence intervals 1.1-5.7). Phylogenetic analysis of partial M gene sequences revealed that all seven positive samples grouped with type I CECoV, the first report of this virus in the UK. None of the positive dogs presented for gastrointestinal disease. Interestingly five of the positive dogs from three separate households were aged over 6 years, suggesting that older dogs may play an important role in the persistence of CECoV in such populations.

This paper discusses the efficacy of cat and dog vaccines, with respect to duration of immunity and regulatory issues. The European Union (EU) regulatory requirements are described: briefly, efficacy claims, which include duration of immunity, have to be specific for the product and supported by controlled laboratory and field trials. As a result, the duration of immunity shown has typically been a minimum, because of the cost and welfare implications of keeping animals for long periods of time in isolation. In contrast, in the US, duration of immunity has not traditionally been required for each individual product, only for rabies vaccines and some other vaccines for which no other products are available. The consequence of this is that in the US, various scientific authorities have produced guidelines appropriate for individual diseases. Undoubtedly this will continue, although the regulatory authorities also appear to be moving towards a position where lack of information may be indicated on the product label, and studies are required to support extended duration of immunity claims. The advantages and disadvantages of laboratory challenge studies versus field trials are discussed, and the use of alternatives such as surrogate markers of protection. The approaches used for small animal vaccines are compared to those used, for example, in human medicine. The main issue for small animals is that unlike in some other species, the aim generally is to maximise protection in the individual, rather than induce protection at the population level. The drawbacks of the present EU system are summarised, and the ways in which the situation is currently being approached and improved are presented.

We have determined the first complete genome sequence and capsid gene sequences of feline calicivirus (FCV) isolates from the UK and Australia. These were compared with other previously published sequences. The viruses used in the comparisons were isolated between 1957 and 1995 from various geographical locations and obtained from cats showing a range of clinical signs. Despite these diverse origins, comparisons between all strains showed a similar degree of sequence variation within both ORF1 (non-structural polyprotein) and ORF2 (major capsid protein) (amino acid distances of 7.7-13.0% and 8.8-18.6%, respectively). In contrast, ORF3 (putative minor structural protein) sequences indicated a more heterogenous distribution of FCV relatedness (amino acid distances of 1.9-17.9%). Phylogenetic analysis suggested that, unlike some other caliciviruses, FCV isolates within the current data set fall into one diverse genogroup. Within this group, there was an overall lack of geographic or temporal clustering which may be related to the epidemiology of FCV infection in cats. Analysis of regions of variability in the genome has shown that, as well as the previously identified variable regions in ORF2, similar domains exist within ORFs 1 and 3 also, although to a lesser extent. In ORF1, these variable domains largely fall between the putative non-structural protein functional domains.

Canine parvovirus (CPV) and feline panleukopaenia virus (FPLV) are two closely related viruses, which are known to cause severe disease in younger unvaccinated animals. As well as causing disease in their respective hosts, CPV has recently acquired the feline host range, allowing it to infect both cats and dogs. As well as causing disease in dogs, there is evidence that under some circumstances CPV may also cause disease in cats. This study has investigated the prevalence of parvoviruses in the faeces of clinically healthy cats and dogs in two rescue shelters. Canine parvovirus was demonstrated in 32.5% (13/50) of faecal samples in a cross sectional study of 50 cats from a feline only shelter, and 33.9% (61/180) of faecal samples in a longitudinal study of 74 cats at a mixed canine and feline shelter. Virus was isolated in cell cultures of both canine and feline origin from all PCR-positive samples suggesting they contained viable, infectious virus. In contrast to the high CPV prevalence in cats, no FPLV was found, and none of 122 faecal samples from dogs, or 160 samples collected from the kennel environment, tested positive for parvovirus by PCR. Sequence analysis of major capsid VP2 gene from all positive samples, as well as the non-structural gene from 18 randomly selected positive samples, showed that all positive cats were shedding CPV2a or 2b, rather than FPLV. Longitudinally sampling in one shelter showed that all cats appeared to shed the same virus sequence type at each date they were positive (up to six weeks), despite a lack of clinical signs. Fifty percent of the sequences obtained here were shown to be similar to those recently obtained in a study of sick dogs in the UK (Clegg et al., 2011). These results suggest that in some circumstances, clinically normal cats may be able to shed CPV for prolonged periods of time, and raises the possibility that such cats may be important reservoirs for the maintenance of infection in both the cat and the dog population.

Feline calicivirus (FCV) has been shown to evolve within individual cats and in the environment of colonies. This evolution and the diversity it creates has important clinical implications, not only for the disease in cats, but also for attempts to control disease by vaccination. Generally speaking, existing vaccines appear to be very effective at controlling the majority of clinical disease. However, some concerns remain including a failure to induce sterilising immunity, occasional vaccine breakdowns, and for live vaccines, occasional vaccine-induced disease. Key areas for future vaccine development include monitoring and broadening the cross-reactivity of vaccine immunity to field viruses, especially the recently evolved highly virulent strains, and attempting to reduce/eliminate field virus shedding by vaccinated cats.

The study determines the sequence evolution of feline calicivirus both in cell culture and in persistently infected cats and relates this to changes in virus neutralisation.

The kobuviruses represent an emerging genus in the Picornaviridae. Here we have used next generation sequencing and conventional approaches to identify the first canine kobuvirus (CaKoV) from outside the USA. Phylogenetic analysis suggests that a single lineage genotype of CaKoV now exists in Europe and the USA with 94% nucleotide similarity in the coding region. CaKoV was only identified in a single case from a case–control study of canine diarrhoea, suggesting this virus was not a frequent cause of disease in this population. Attempts to grow CaKoV in cell culture failed. Sequence analysis suggested CaKoV was distinct from human Aichi virus (AiV), and unlikely to pose a significant zoonotic risk. Serosurveys by ELISA, immunofluorescence and neutralisation tests, using AiV as antigen, suggested kobuvirus infection is prevalent in dogs. In addition, IgG antibody to AiV was also detected in cat sera, indicating for the first time that cats may also be susceptible to kobuvirus infection.