Experimental Infection of Bulls with a Genital Isolate of Bovine Herpesvirus-4 and Reactivation of Latent Virus with Dexamethasone

Five 13- to 18-month old Belgian Blue bulls were used in this experiment. Four bulls (Nos. 2, 3, 4 and 5) were inoculated intratesticularly with 10(5) plaque-forming units of bovine herpesvirus-4 (BHV-4) in each testicle (Day 0). The challenge BHV-4 strain was previously isolated from testicle cells of a bull exhibiting orchitis and azoospermia. The fifth bull (No. 1) was used as a control and received the same volume of uninfected cell culture supernatant. For 5 days, beginning on Day 51 post-infection, two bulls (Nos. 4 and 5) and the control bull (No. 1) received 0.1 mg kg-1 of dexamethasone. Unilateral castrations were then performed at regular intervals for viral examination. Treatment with dexamethasone reactivated latent BHV-4, but no clinical signs were observed in treated bulls until the end of the experiment (Day 93). Only Bull 3 showed conjunctivitis and temporary azoospermia. The virus was recovered from various samples showing that: (i) BHV-4 can be present in a latent state in the testicles and mononuclear blood cells; (ii) dexamethasone reactivates the virus; (iii) the virus is excreted by nasal and ocular routes. Each infected bull seroconverted and a booster antibody response appeared after dexamethasone treatment as shown by immunofluorescence. Neutralizing antibodies were detected in each bull by complement-dependent neutralization test with titres higher than those obtained by a classical neutralization test. No booster response of neutralizing antibodies was observed after dexamethasone treatment. The antigenically relevant envelope BHV-4 proteins were identified by Western blotting using sera samples from the animals. DNA restriction endonuclease profiles of viruses reisolated after primary infection and reactivation showed only small differences

Rescue of a pathogenic Marek's disease virus with overlapping cosmid DNAs: Use of a pp38 mutant to validate the technology for the study of gene function

Marek's disease virus (MDV) genetics has lagged behind that of other herpesviruses because of the lack of tools for the introduction of site-specific mutations into the genome of highly cell-associated oncogenic strains. Overlapping cosmid clones have been successfully used for the introduction of mutations in other highly cell-associated herpesviruses. Here we describe the development of overlapping cosmid DNA clones from a very virulent oncogenic strain of MDV. Transfection of these cosmid clones into MDV-susceptible cells resulted in the generation of a recombinant MDV (rMd5) with biological properties similar to the parental strain. To demonstrate the applicability of this technology for elucidation of gene function of MDV, we have generated a mutant virus lacking an MDV unique phosphoprotein, pp38, which has previously been associated with the maintenance of transformation in MDV-induced tumor cell lines. Inoculation of Marek's disease-susceptible birds with the pp38 deletion mutant virus (rMd5Δpp38) revealed that pp38 is involved in early cytolytic infection in lymphocytes but not in the induction of tumors. This powerful technology will speed the characterization of MDV gene function, leading to a better understanding of the molecular mechanisms of MDV pathogenesis. In addition, because Marek's disease is a major oncogenic system, the knowledge obtained from these studies may shed light on the oncogenic mechanisms of other herpesviruses

New opportunities for farm accounting

This paper starts out to observe that there is a gap between the importance given to accounting and the low level of bookkeeping and accounting practice in the agricultural sector. Reasons for this gap are that current general accounting rules do not adapt very well to the particularities of farming and are difficult and expensive to implement. We then suggest that the Farm Accountancy Data Network (FADN) and the recently issued International Accounting Standard on Agriculture (IAS 41) could be key elements to improve the use of accounting in European farms. We review the main contributions of IAS 41 and conclude that it provides a strong conceptual framework but might need further instruments for its implementation in practice, given the limitations of the agricultural sector. We continue to explain that FADN is an experienced network that has elaborated very detailed farm accounting procedures, and suggest that these procedures could be turned into a guide for implementing IAS 41. We report empirical data which indicate that current FADN reports are already considered useful by farmers for different purposes. Finally, we analyse in detail the compatibility of IAS 41 and FADN, identifying changes in the FADN procedures that would become necessary if the FADN procedures were to be used for implementing IAS 41 and some aspects of FADN that might have been worthwhile to consider for the final version of IAS 41.