Annales de recherches veterinaires. Annals of veterinary research最新文献

Two groups, A and B, of two specific pathogen-free pregnant sows were experimentally infected between the 25th and 29th days post-breeding with two strains of ruminant pestivirus: NADL cytopathic bovine viral diarrhoea virus for group A and Aveyron non-cytopathic border disease virus French strain for group B. Two other pregnant sows (group C) were kept uninoculated as control. When 7 weeks old, 8 piglets of group C were put in contact with 4 piglets of group A (group D), and 8 other piglets of group C with 4 piglets of group B (group E) in two separate pens with the purpose of testing the horizontal transmission of the viruses. All animals were kept under observation and serologically controlled at weekly intervals; two pigs of each group were finally submitted to a challenge with hog cholera virus. The two pigs of group E which were put in contact with the offspring of the border disease virus infected sow were protected; all other animals developed typical hog cholera symptoms and died. The relation between neutralizing titres of the sera to ruminant pestiviruses and protection to the challenge with hog cholera virus is discussed. The two protected pigs had high neutralizing antibody titres to border disease virus but no antibody to hog cholera virus at the time of the challenge. Though the two viruses look serologically distant, we surprisingly observed that infection with border disease virus protects against a superinfection with hog cholera virus.

In lymphoid tissue, the presence of high amounts of free proteins and immunoglobulins frequently leads to the observation of non-specific reactivities during immunohistochemical reactions. The types of anti-immunoglobulin sera utilized in these immunohistochemical reactions may be capable of identifying immunoglobulins secreted or harboured by the tissue cells under study, leading to non-specific marking. Incubation of these antisera with serum from the species in which the lymphoid tissue is studied neutralizes the non-specific reactivities connected with the presence of tissue immunoglobulins.

Copper status determined by liver biopsy was also assessed by 3 plasma parameters: total plasma copper (Cu) as well as ceruloplasmin (Cp) and amine oxidase E.C.1.4.3.6. (AO) activities. While 14 out of the 98 cattle, all kept in field conditions, had liver copper levels of less than 20 mg/kg only 5 of these could be distinguished by low plasma Cu and 3 by low Cp activity. In addition, some animals with apparently adequate liver copper had relatively low plasma Cu values, ca 0.5-0.6 mg/l. None of the cattle had decreased AO activity. When all 3 plasma parameters were combined in the form [AO] divided by ([Cp] x [Cu]), detection of the low liver copper was improved in that 9 out of 14 could be distinguished, whereas animals with more than 20 mg/kg DM liver Cu could not. It is suggested that this relationship, tentatively called an index, would merit examination in other situations, since it might provide a better guide to copper status and indicate whether copper repletion therapy was worthwhile.

The influence of the state of pregnancy (mid- and end of pregnancy) on the kinetic disposition of gentamicin was determined in the ewe. Kinetic parameters were determined after a single intravenous bolus administration (4 mg/kg). It was shown that the steady state volume of distribution was significantly increased from mid to end of pregnancy (from 0.09 I.kg-1 to 0.194 I.kg-1). Similarly, plasma clearance was increased by about 150% at the end of pregnancy. These modifications must be taken into account in order to adapt the dosage regimen and determine a withdrawal time for gentamicin.

We describe the first known occurrence in France of the porcine reproductive and respiratory syndrome (PRRS), a new porcine disease that first appeared in Germany in November 1990. Outbreaks of the disease appeared in November 1991 in Brittany (France), with comparable clinical features to those observed in other countries, were definitively confirmed by a serological analysis from the affected animals using an immunoperoxidase monolayer assay with PRRS-virus infected alveolar macrophages. Furthermore, we report the isolation from one serum of a filtrable agent that, in view of its cytopathic effect for porcine alveolar macrophages and of the serologic reactivity of the infected cells, appears similar to the Lelystad virus that has been implicated in the etiology of the disease.