Safety of an Aujeszky's disease vaccine based on deletion mutant strain 783 which does not express thymidine kinase and glycoprotein I

The safety of an Aujeszky's disease virus vaccine based on strain 783, a deletion mutant which does not express glycoprotein I and thymidine kinase, was assessed in pigs, calves and sheep. Four-day-old piglets which were inoculated intranasally and intramuscularly with 10(7) plaque forming units (PFU) developed only slight depression and fever. The virus was transmitted to a sentinel piglet. Six weeks after inoculation, the pigs were injected with high doses of corticosteroids in an attempt to reactivate the vaccine virus. The pigs did not shed Aujeszky's disease virus, did not develop a rise in virus neutralising antibody titres and sentinel pigs remained seronegative to Aujeszky's disease virus. Strain 783 was passaged in two series of three- to five-day old piglets, but after the third and fourth passages virus could no longer be recovered. Pregnant sows were inoculated with 10(7) PFU of virus strain 783 around day 35 or on day 85 of pregnancy, and their fetuses and piglets were assayed for Aujeszky's disease virus and antibodies against Aujeszky's disease virus. No evidence was found for transplacental transmission of the virus. Calves and sheep were given 10(7) PFU of virus strain 783 intranasally or intramuscularly; they survived and did not develop clinical signs of Aujeszky's disease. All the sheep and the calves inoculated intramuscularly developed neutralising antibodies to Aujeszky's disease virus.     

Efficacy of a pseudorabies virus vaccine based on deletion mutant strain 783 that does not express thymidine kinase and glycoprotein I.

The vaccine efficacy of a genetically engineered deletion mutant strain of pseudorabies virus, strain 783, was compared with that of the conventionally attenuated Bartha strain. Strain 783 has deletions in the genes coding for glycoprotein I and thymidine kinase. In experiment 1, which had a 3-month interval between vaccination and challenge exposure, strain 783 protected pigs significantly (P less than 0.05) better against virulent virus challenge exposure than did the Bartha strain. The growth of pigs vaccinated with strain 783 was not arrested, whereas that of pigs vaccinated with the Bartha strain was arrested for 7 days. Of 8 pigs given strain 783, 4 were fully protected against challenge exposure; none of the pigs given strain Bartha was fully protected. In experiment 2, which had a 3-week interval between vaccination and challenge exposure, the growth of pigs vaccinated with strain 783 was arrested for 3.5 days, whereas that of pigs vaccinated with the Bartha strain was arrested for 6 days. In experiment 3, pigs with moderate titer of maternal antibodies were vaccinated twice IM or once intranasally with either strain 783 or Bartha and were challenge-exposed 3 months after vaccination. Pigs given strain 783 twice IM were significantly (P less than 0.05) better protected than were the other pigs. They had growth arrest of only 6 days, compared with 9 days for pigs of other groups, and shed less virus after challenge exposure. Results of this study indicate that the vaccine based on the deletion mutant strain 783 is more efficacious than is the Bartha strain of pseudorabies virus.     

Neurobiological substrates of dread

Given the choice of waiting for an adverse outcome or getting it over with quickly, many people choose the latter. Theoretical models of decision-making have assumed that this occurs because there is a cost to waiting-i.e., dread. Using functional magnetic resonance imaging, we measured the neural responses to waiting for a cutaneous electric shock. Some individuals dreaded the outcome so much that, when given a choice, they preferred to receive more voltage rather than wait. Even when no decision was required, these extreme dreaders were distinguishable from those who dreaded mildly by the rate of increase of neural activity in the posterior elements of the cortical pain matrix. This suggests that dread derives, in part, from the attention devoted to the expected physical response and not simply from fear or anxiety. Although these differences were observed during a passive waiting procedure, they correlated with individual behavior in a subsequent choice paradigm, providing evidence for a neurobiological link between the experienced disutility of dread and subsequent decisions about unpleasant outcomes.     

Search for Climatic Models for Forecasting Microtine Outbreaks1

Models for forecasting outbreaks of harmful Microtines are discussed in terms of the three most important types of rodent damage to agriculture and forestry in the European part of EPPO region: problems to field crops by Microtus arvalis and related species, to horticulture and forestry by M. agrestis and some other species, and injury to the underground parts of various crops by Arvicola terrestris. Two models were developed in parallel but independently for M. arvalis, one in the USSR, the other in France; the former approach included M. socialis. A joint Scandinavian project resulted in models for M, agrestis and Clethrionomys glareolus: the outcome is exemplified by the former case and a few comments are given on other types of model development. The probable mechanism of climatic influence through the food chain on the population dynamics of Microtine rodents is discussed and it is concluded that climatic models are a useful tool in planning rodent control strategies. The role of the EPPO Working Party on Field Rodents as a coordinating body in the development of rodent forecasts is also reviewed.     

POSITRON EMISSION TOMOGRAPHY FEATURES OF CANINE NECROTIZING MENINGOENCEPHALITIS

A Yorkshire terrier and a Chihuahua were referred for acute onset, generalized tonic‐clonic seizures and were suspected to have meningoencephalitis based on magnetic resonance (MR) imaging findings. Brain lesions appeared hyperintense with T2‐weighted imaging and hypointense with T1‐weighted imaging, and were characteristic of necrotizing meningoencephalitis. Both dogs were diagnosed with necrotizing meningoencephalitis based on pathologic findings. Fluorine‐18 fluorodeoxyglucose positron emission tomography (FDG‐PET) was performed on both animals before euthanasia with the permission of the owner. In FDG‐PET images, these lesions seen in MR images were characterized by multifocal or diffuse hypometabolism. Our FDG‐PET results provided evidence of glucose hypometabolism in areas of necrosis and cavitation associated with necrotizing meningoencephalitis. FDG‐PET has the potential to provide valuable diagnostic information in dogs with suspected necrotizing encephalitis.