Simultaneous vaccination of piglets against foot-and-mouth disease and classical swine fever.

Six-week-old piglets, born of unvaccinated sows, were vaccinated against foot-and-mouth disease (FMD) with a trivalent, inactivated vaccine containing an adjuvant or vaccinated against classical swine fever (CSF) with a live attenuated vaccine or against both diseases simultaneously at two different sites. The antibody response to the FMD vaccine was not significantly influenced by the simultaneous vaccination against CSF. FMD vaccine administered simultaneously with the CSF vaccine produced a significantly higher antibody response to CSF than occurred with CSF vaccination only.

The serological response to foot-and-mouth disease vaccination is not affected by simultaneous infectious bovine rhinotracheitis/adenovirus/parainfluenza 3 vaccination.

Young calves were simultaneously vaccinated by subcutaneous route against foot-and-mouth disease (FMD) and against infectious bovine rhinotracheitis/adenovirus/parainfluenza-3 (IBR/Adeno/PI-3) by intranasal route. The serological response against the 3 FMD virus types of the FMD vaccine was clearly positive. There was no significant difference between results of simultaneous FMD and IBR/Adeno/PI-3 vaccination and FMD vaccination only.

Serological response to a booster foot-and-mouth disease vaccination with strains different from the primary vaccine.

Young calves were vaccinated with belgian foot-and-mouth disease (FMD) vaccine and revaccinated with either the same vaccine or with a foreign FMD vaccine. There was a significant serological response to the primary vaccine strains after the first vaccination which was greater following revaccination. At one and two months after revaccination there was no significant difference between the responses to revaccination with vaccine identical to the primary vaccine or with the foreign FMD vaccine. It was concluded that revaccination of young calves is effective even with an FMD vaccine different from the primary vaccine.

Routine titration of foot-and-mouth disease virus suspensions by analytical ultracentrifugation 2nd communication: sedimentation equilibrium method.

A routine method for the determination of the virus concentration in FMD virus cultures and vaccines was developed. This method was based on sedimentation equilibrium in the analytical ultraviolet scanning ultracentrifuge. The virus suspension was first clarified. The virions were then sedimented in a preparative ultracentrifuge. The resuspended virions were diluted in a Cesium chloride solution and brought to equilibrium in the density gradient generated in the analytical ultracentrifuge. The optical density of the virus band was measured by the UV scanning system. A calculation procedure was developed to compute the density at the limits and at the maximum of the virus band. The virus concentration expressed as weight, was calculated for the original virus suspension.

Studies about the adjuvant activity of saponin fractions in foot and mouth disease vaccine. III. Comparison of the irritant, adjuvant and hemolytic activities of six commercial saponins and their hemolytic fractions obtained by chromatography on sephadex G 100.

12 experimental vaccines were prepared to compare the irritant and adjuvant activity in cattle of 6 commercial saponin preparations and their hemolytic fractions. It is still not known if a single substance is responsible for the irritant, adjuvant and hemolytic activities of the saponin preparations. The quantities of saponin added were standardised on the base of a constant hemolytic activity rather than on a weight of powder per dose of vaccine base. A FMD vaccine was used to reveal the adjuvant activity. It was concluded that the irritation is related to the hemolytic activity and not to the weight of powder. Irritation is slightly reduced when a toxic effect appears. The adjuvant activity was higher for untreated saponin preparations with high hemolytic activity used at low dose and for one of the chromatographic saponin fractions. The adjuvant activity is reduced when toxic effect appear. Toxicity of less hemolytic saponins used at high dose is removed by chromatography. Highly hemolytic saponins used at low dose become toxic after chromatographic treatment.

Routine titration of foot and mouth disease virus suspensions by analytical ultracentrifugation. 1: Sedimentation method.

Infectivity and Complement Fixation (CF) tests are commonly used for the routine titration of Foot and Mouth Disease (FMD) virus suspensions. Only recently were techniques published for the routine determination of the virus concentration by the physical properties of the virions (Fayet et al., 1971; Barteling et al., 1974). These techniques are based on the separation of the virions from the culture fluid by sedimentation through a sucrose gradient, in a preparative ultracentrifuge. The ultraviolet absorption pattern of the tube content is recorded by a flow colorimeter. The virus concentration is estimated using either standard curves or direct caculation by the specific extinction coefficient (Bachrach et al., 1964). In our own attempts to develop a preparative ultracentrifugation technique for the routine titration of FMD virus suspensions, we had to deal with some problems such as remixing of the virus band at the end of the run. We therefore turned over to analytical ultracentrifugation methods. The manipulations are less complicated and the virus band is traced and measured while the rotor is spinning. Four samples are analyzed simultaneously and the scans are repeated to follow the move of the virus band. The sedimentation rate of the virus band, calculated from the repeated scans, helps to detect artifacts. The present paper describes the technique we developed for the routine titration of FMD virus suspensions, by the band sedimentation method, using an ultraviolet scanning analytical ultracentrifuge.