Evaluation of an in-practice test for feline coronavirus antibodies

A commercially available in-practice test for feline coronavirus (FCoV) antibodies (FCoV Immunocomb, Biogal Galed Laboratories) was evaluated by comparison with the gold standard FCoV immunofluorescent antibody (IFA) test. One hundred and three serum or plasma samples were selected and tested: 70 were positive by both tests, 24 were negative by both tests. The in-practice test produced five false positive and four false negative results. The sensitivity of the in-practice test was 95% and the specificity was 83%. When the titres were compared it was found that the in-practice test results were significantly correlated with IFA titres but the degree of correlation was not likely to be clinically useful. The IFA titres of the four false negative samples were found to be low (less than 40) which suggests that even a cat with a false negative result is still unlikely to be excreting FCoV. A negative result with the in-practice assay is likely to be reliable for screening cats prior to entry into an FCoV-free cattery or stud. It would also be useful in the investigation of suspected FIP as most cats with this condition have high IFA titres of antibodies. A strong positive result would be useful in the diagnosis of FIP (in conjunction with other biochemical and cytological testing), but positive results would be of limited value in monitoring FCoV infection in healthy cats as the antibody titre could not be reliably compared with those obtained with IFA. All positive results obtained using the in-practice kit should be confirmed and titrated by IFA. The kit also appeared to work efficiently with ascites samples (n=6) but too few samples were analysed to draw firm conclusions.     

A test of two methods for marking larvae and postlarvae of the giant freshwater prawn, Macrobrachium rosenbergii

This paper describes the successful use of two tagging systems, both produced by Northwest Marine Technology Inc., on larval and postlarval giant freshwater prawns, Macrobrachium rosenbergii. Visible implant (VI) elastomer tags (a coloured liquid that solidifies under the epidermis) were used on stage XI larval prawns (mean weight 0.01 g) and postlarval prawns (mean weight 0.07 g). VI alphanumeric tags (small biocompatible plastic labels also inserted under the epidermis) were tested on postlarval prawns (from a weight of 0.5 g). Tags were inserted using clove oil as anaesthetic, and survival, mortality and growth rates of tagged animals were compared with those of controls that were handled but not anaesthetized or marked. Twenty per cent of the larval prawns (the smallest of the group) died just after tagging, but thereafter the remaining prawns survived well, as did all the tagged postlarval prawns. Visibility of the VI elastomer tags in larval prawns deteriorated with time, though 79% of marks were still visible to the naked eye 70 days after tagging. VI elastomer tags in the postlarval group remained clearly visible for up to 100 days. Visibility of the VI alphanumeric tags fell shortly after tagging, but remained adequate thereafter. Moult rates in control and tagged animals were the same in larvae with VI elastomer tags and postlarvae with VI alphanumeric tags, but the moult rate in the postlarval prawns given elastomer tags was slower than in controls. Rates of growth were similar in tagged (elastomer and alphanumeric) and control postlarval prawns, once the size‐dependent mortality of tagged larval prawns was taken into account. We conclude that VI elastomer tags could be used to mark small numbers of individual larval and immediately postlarval prawns for periods of several months, and that VI alphanumeric tags could be used to mark an unlimited number of individuals from a size of approximately 0.5 g.     

Effects of long-term exposure to enriched CO<Subscript>2</Subscript> on the nutrient-supplying capacity of a grassland soil

Altered soil nutrient cycling under future climate scenarios may affect pasture production and fertilizer management. We conducted a controlled-environment study to test the hypothesis that long-term exposure of pasture to enriched carbon dioxide (CO₂) would lower soil nutrient availability. Perennial ryegrass was grown for 9 weeks under ambient and enriched (ambient + 120 ppm) CO₂ concentrations in soil collected from an 11.5-year free air CO₂ enrichment experiment in a grazed pasture in New Zealand. Nitrogen (N) and phosphorus (P) fertilizers were applied in a full factorial design at rates of 0, 12.5, 25 or 50 kg N ha⁻¹ and 0, 17.5 or 35 kg P ha⁻¹. Compared to ambient CO₂, under enriched CO₂ without P fertilizer, total plant biomass did not respond to N fertilizer, and tissue N/P ratio was increased indicating that P was co-limiting. This limitation was alleviated with the lowest rate of P fertilizer (17.5 kg P ha⁻¹). Plant biomass in both CO₂ treatments increased with increasing N fertilizer when sufficient P was available. Greater inputs of P fertilizer may be required to prevent yield suppression under enriched CO₂ and to stimulate any response to N.     

Lower soil nitrous oxide emissions by a high lipid genetically modified perennial ryegrass line compared to its wild type

We describe an experiment where cattle urine was applied at a rate of 420 kg N ha⁻¹, equivalent to 10 L m⁻², to mesocosm swards of a high lipid genetically modified perennial ryegrass line (HME) and its wild type (WT). We measured N pools and fluxes in the plant and soil, soil microbial populations and N₂O production. HME plants produced 21% greater biomass than WT (p = .02), resulting in greater N uptake (27% higher in HME, p = .05). Urine N recovery in total plant biomass during the experiment in HME and WT swards were 54.7% and 33.9% respectively. The nitrification potential of soil was significantly lower (p = .01) in HME than WT. Partial least square-discriminant analysis using microbial gene abundance data indicated that HME and WT plant growth induced distinct microbial populations in the soil. These differences in plant soil microbial interactions between HME and WT swards resulted in significantly lower N₂O emissions from the HME sward. Total N₂O emissions over the 4 weeks after urine application was 38% lower (p < .03) in HME swards than in WT swards. The next step in this work is to identify the specific changes in HME traits that drive the reduction in N₂O.     

Occurrence of barley yellow dwarf virus in autumn-sown cereal crops in the United Kingdom in relation to field characteristics

The incidence of barley yellow dwarf virus and of its aphid vectors was surveyed in untreated parts of autumn-sown cereal crops, mainly wheat and barley, in the United Kingdom in 1995-8. The incidence of virus in the spring was related to the incidence of aphids in the preceding autumn. Both virus and aphid incidences could also be related to a range of crop and field characteristics, in particular sowing date, regions as defined by their geographical position, topography and climate, the proximity of the field to the sea, the extent of arable land in the vicinity of the field, and the aspect and size of the field. Proximity of cropped fields to setaside areas had no significant effect on either aphid or virus incidence.     

Antigenic and genetic variations in European and North American equine influenza virus strains (H3N8) isolated from 2006 to 2007

Equine influenza virus (EIV) surveillance is important in the management of equine influenza. It provides data on circulating and newly emerging strains for vaccine strain selection. To this end, antigenic characterisation by haemaggluttination inhibition (HI) assay and phylogenetic analysis was carried out on 28 EIV strains isolated in North America and Europe during 2006 and 2007. In the UK, 20 viruses were isolated from 28 nasopharyngeal swabs that tested positive by enzyme-linked immunosorbent assay. All except two of the UK viruses were characterised as members of the Florida sublineage with similarity to A/eq/Newmarket/5/03 (clade 2). One isolate, A/eq/Cheshire/1/06, was characterised as an American lineage strain similar to viruses isolated up to 10 years earlier. A second isolate, A/eq/Lincolnshire/1/07 was characterised as a member of the Florida sublineage (clade 1) with similarity to A/eq/Wisconsin/03. Furthermore, A/eq/Lincolnshire/1/06 was a member of the Florida sublineage (clade 2) by haemagglutinin (HA) gene sequence, but appeared to be a member of the Eurasian lineage by the non-structural gene (NS) sequence suggesting that reassortment had occurred. A/eq/Switzerland/P112/07 was characterised as a member of the Eurasian lineage, the first time since 2005 that isolation of a virus from this lineage has been reported. Seven viruses from North America were classified as members of the Florida sublineage (clade 1), similar to A/eq/Wisconsin/03. In conclusion, a variety of antigenically distinct EIVs continue to circulate worldwide. Florida sublineage clade 1 viruses appear to predominate in North America, clade 2 viruses in Europe.     

Mucopolysaccharidosis type VI in a juvenile miniature schnauzer dog with concurrent hypertriglyceridemia,necrotizing pancreatitis,and diabetic ketoacidosis

A 7-month-old, neutered male miniature schnauzer dog with a history of cryptorchidism and umbilical hernia was referred for diabetic ketoacidosis. Clinical evaluation revealed stunted growth, skeletal abnormalities, hypertriglyceridemia, diabetic ketoacidosis, and acute necrotizing pancreatitis. Further testing was diagnostic for mucopolysaccharidosis type VI causing the stunted growth and skeletal deformities, but no connection between mucopolysaccharidosis type VI, hypertriglyceridemia, and pancreatic diseases was found.     

Reference genes for canine skin when using quantitative real-time PCR

Quantitative real-time PCR (qPCR) facilitates the quantification of mRNA expression. Accurate qPCR analysis of gene expression requires the normalisation of data using a reference or housekeeping gene which is expressed at a similar level in all tissues tested. GAPDH is the most well known and most widely used reference gene but many papers have demonstrated that it is not stably expressed in different tissues. The aim of this study was to measure reference gene stability in canine skin using real-time qPCR. Skin samples from healthy control dogs (n=7) and dogs with atopic dermatitis (lesional skin n=7 and non-lesional skin n=7) were used to quantify seven reference genes (IMP, CG14980, S7, HIRA, GAPDH, RPL13A and SDHA) in canine whole skin. Three different statistical programs (Bestkeeper, GeNorm and Normfinder) were used to assess the stability of the reference genes. The results confirmed that GAPDH is not a stably expressed reference gene in canine skin; this finding may influence interpretation of previous qPCR studies on canine skin using this as a reference gene. RPL13A and CG14980 were found to be the most stably expressed genes in canine whole skin and would be more suitable as reference genes in future studies.