Studies on the contribution of the left unique region of the genome to Murine Gammaherpesvirus-68 pathogenesis

Members of the gamma subgroup of the herpesvirus family are characterised by their ability to establish lifelong latent infection in lymphocytes, and their association with lymphoproliferative disease and a range of malignant tumours. Members include the Epstein-Barr virus (EBV) and Kaposi's sarcomaassociated herpesvirus (KSHV), which are linked with clinically important human diseases, as well as alcelaphine herpesvirus 1 (A1HV-1) and ovine herpesvirus 2 (OvHV-2), which are of veterinary importance. Due to the severe limitations on the study of gammaherpesviruses presented by their species specificity and restricted growth in vitro, infection of laboratory mice with the naturally occurring virus murine gammaherpesvirus 68 (MHV-68) has become an excellent model system for the study of gammaherpesvirus pathogenesis.This project involved the characterisation of murine herpesvirus 76 (MHV-76), another of the murine herpesviruses isolated at the same time as MHV-68. Molecular analysis revealed that MHV-76 is a deletion mutant of MHV-68, that lacks four genes unique to MHV-68 (Ml, M2, M3 and M4) and eight viral tRNA-like genes that are all present at the left end of the MHV-68 genome. Biological characterisation of MHV-76, including the generation and study of rescue viruses which restored the deleted sequence into MHV-76, showed that loss of these genes leads to enhanced clearance of virus from the lungs due to a vigorous inflammatory response. There was also a significant reduction in splenomegaly and the amount of latent virus detectable in the spleen. These results show that the genes present at the left end of the unique region of the MHV-68 genome play a critical role in the viral immune evasion strategy.Detailed studies on one of these unique MHV-68 genes, M2, show that it is a 30kDa protein that has localised homology with the Gab2 and semaphorin protein families. Expression of M2 in mammalian cells reveals that it co-localises to the plasma membrane, as well as being present in diffuse areas of the nucleus and cytoplasm. Generation of a recombinant virus with a disruption in the M2 ORE showed that the M2 gene plays a critical role in the establishment of latency and the regulation of the numbers of latently infected cells in the spleen. The M2 gene is not involved in the genesis of splenomegaly. These studies uncover some of the genetic elements involved in gammaherpesvirus pathogenesis

An immunoturbidimetric assay for bovine haptoglobin

In cattle, the serum protein haptoglobin (Hp) is a major acute phase protein (APP) that rises in concentration over a thousand fold following stimulation by pro-inflammatory cytokines. As such, this APP is a valuable biomarker for infection, inflammation and trauma in cattle. The assay for bovine Hp is becoming more commonplace in clinical pathology and in experimental studies when a biomarker of innate immunity is required. The most widely used assay for Hp utilises its binding to haemoglobin (Hp-Hb binding assay), which at low pH enables the preservation of the native peroxidase activity in the haemoglobin. This assay is used for all species, including species such as dog, cat and pig where the level of Hp is higher in healthy animals of these species than in healthy cattle, and therefore a bovine-specific immunoassay that can be automated would be desirable. Thus, a novel-automated species-specific immunoturbidimetric (IT) assay has been developed. Validation studies showed intra- and inter-assay CVs of below 5% and 9% respectively and a recovery of 99% from samples spiked with bovine Hp and a limit of quantification of 0.033 g/L. The assay is not affected by icterus or lipaemia but had moderate interference from haemoglobin and showed a significant correlation with the Hp-Hb binding assay. This novel IT assay for bovine Hp will allow automated analysis of this important bovine APP to identify changes in the Hp concentration not detectable by current Hp-Hb binding assays. It will enable the incorporation of this assay into herd health assessments, animal welfare analysis and for bovine medicine and research

The effect of the climatic housing environment on the growth of dairy-bred calves in the first month of life on a Scottish farm

SIMPLE SUMMARY: The climatic environment within calf housing can have an effect on calf health, but also on growth and performance. Calves have a lower threshold environmental temperature (lower critical temperature, LCT), below which can impact on the calf’s ability to maintain its core body temperature. This can cause the calf to partition more of its available energy into heat production and less into growth. The LCT decreases as the calf gets older. This year-long study followed 299 dairy-bred calves on one farm in Scotland from birth until approximately 28 days of age, and looked at the proportion of time for which the temperature was below the LCT for the individual calf, as well as the daily liveweight gain (DLWG; kg/d) of the calves during this time. For their first 6–14 days of life the calves were individually housed, and then subsequently group housed. Air temperature (°C), relative humidity (%), and wind speed (m/s) were recorded every hour of every day throughout the study, and calves were weighed regularly so that DLWG could be calculated. The study demonstrated that calves that spent a high proportion of their time below their LCT had a lower DLWG compared to calves that spent a low proportion of their time below their LCT. ABSTRACT: Calf housing is naturally thermodynamic, with interactions between various elements such as wind speed, air temperature, and humidity. This study investigated the effect of the proportion of time for which calves were exposed to effective environmental temperatures below their lower critical temperature (LCT) on their daily liveweight gain (DLWG) within their first month of life. This study used the naturally occurring climatic environment, whereas other such studies have been conducted under climatically controlled conditions. Air temperature (°C), relative humidity (%), and wind speed (m/s) were recorded within the calf housing from birth until approximately 28 days of age, with calves being health-scored and weighed at regular intervals. Calves were housed from birth until 6–14 days old in individual hutches, and then moved into group housing igloo pens. Whilst individually housed, calves that spent less than 32% of their time below their LCT had a DLWG of 0.06 ± 0.34 kg/d (mean ± SE) compared to calves that spent more than 97% of their time below their LCT, which had a DLWG of −0.19 ± 0.045 kg/d. When group housed, calves that spent less than 1% of their time below their LCT had a DLWG of 0.59 ± 0.18 kg/d, whereas calves that spent more than 28% of their time below their LCT had a DLWG of 0.53 ± 0.23 kg/d. The proportion of time for which calves were exposed to effective environmental temperatures below their LCT had a significant effect on DLWG when calves were individually housed. Therefore, exposure to effective environmental temperatures below the LCT can be detrimental to the growth of the calf in the early stages of its life