Experimental squalene adjuvant. II. Harmlessness and local reactogenity.

Model experiments on laboratory animals (guinea pigs) were carried out to test the possible allergic reaction (possibility of sensitisation) to the repeated administration of an experimental lipoid adjuvant prepared on the basis of squalene (experimental squalene adjuvant--ESA). No significant differences were observed between the animals sensitised-provoked with ESA and control animals. In order to evaluate the local tissue reactivity (local reactogenity), also with regard to the process dynamics to the administration of ESA, comparative patho-anatomical and patho-histological examinations of tissues were carried out in the location of adjuvant administration. The examinations indicated very low local reactogenity of the experimental lipoid adjuvant prepared in our laboratory. The test of pyrogenicity also confirmed the safety of ESA, the labelled lysate sensitivity lambda was under 0.25 IU/cm3.

Experimental squalene adjuvant. I. Preparation and testing of its effectiveness.

The authors prepared experimental lipoid adjuvant of the oil-in-water (O/W) type, based on squalene (ESA: experimental squalene adjuvant), intended for liquid inactivated veterinary vaccines. The final concentration of squalene in the vaccine was 5% (w/v). Detergents Poloxamer 105 in the concentration of 4% (w/v) and Abil-Care in the concentration of 2% were used as emulsifiers. The water component was inactivated virus suspension. Emulsification at decreased temperatures (up to 37 degrees C) fails to denaturate the immunization antigen. The effectiveness of experimental squalene adjuvant was tested using a liquid inactivated adjuvant rabies vaccine and a liquid porcine parvovirus vaccine in comparison with adjuvant-free vaccines or vaccines potentiated with aluminium hydroxide. The squalene adjuvant increased the immunogenic activity of non-potentiated rabies vaccine approximately 1.8-fold, while aluminium hydroxide increased the effectiveness of rabies vaccine only 1.08-fold. The antigenic activity, i.e. the level of specific antibodies after vaccination was significantly increased by using both adjuvants; ESA was more efficient than aluminium hydroxide.

Effect of ovariohysterectomy on canine postsurgical leukocyte function.

The effect of surgery on phagocytic activity of blood leukocytes and mitogen-induced blastogenesis of lymphocytes was studied in fourteen dogs. Simple ovariohysterectomy with anaesthesia induced by ketamine and xylazine or by ketamine, xylazine and halothane caused a short nonsignificant depression of phagocytic activity that persisted for four hours after surgery. Ingestion capacity of leukocytes decreased significantly immediately after surgery. Mitogen-induced blastogenesis of lymphocytes was depressed significantly in the first 48 hours and despite partial recovery this parameter did not reach the value of the control groups until the end of observation (7 days). A more conspicuous decrease of blastogenic response of blood lymphocytes to mitogens was found after the use of ketamine and xylazine in a dose maintaining anaesthesia. Anaesthesia with ketamine and xylazine in the lower dose and maintained with halothane resulted in a later improvement of the blastogenic response of lymphocytes.

A survey for BVDV antibodies in cattle farms in Slovakia and genetic typing of BVDV isolates from imported animals.

A serological survey for bovine viral diarrhoea virus (BVDV) antibodies on a collection of 1295 serum samples obtained from 6-12 months old cattle originating from 45 farms in Slovakia was carried out. On 13 farms more than 90% of the examined animals were seropositive, on 14 farms 71-90% seroprevalence was observed, on 13 farms only 50-70% animals were found to be positive for BVDV antibodies, while the remaining 5 farms showed fewer than 50% seropositive animals. The average incidence of BVDV antibodies (around 70%) was similar as determined 30 years ago. Of 84 serum samples from seronegative animals originating from 14 farms in which 70-98% seropositivity was observed, six were positive in Ag-BVDV ELISA indicating persistently infected (PI) cattle. On a farm to which animals were imported from abroad, a BVD outbreak was observed. Of 110 animals tested, four were positive in Ag-ELISA indicating the presence of PI cattle on this farm. Genetic typing of two isolates from imported animals performed by RT-PCR (324/326 primers from 5'-UTR), sequencing of PCR products and computer-assisted phylogenetic analysis revealed that they belong to BVDV-1 h group.