| Foot-and-mouth disease is among the most infectious and contagious diseases. It causes great economic losses to livestock producers and the national economy, the direct losses being due to death in calves, loss of milk yield, loss of weight in beef cattle from chronic lameness. Indirect consequences include devaluation of animal and animal products and restriction of trade.;The influence of various replicative systems on plaque sizes was studied. Plaque sizes of virus replicating in mice, guinea pigs and bovine tongue epithelium were predominantly large. The monolayer cells-produced virus remained as large plaques until passage level 5, from there on, the mean plaque sizes started to decrease. The suspension cells-propagated virus, however, produced predominantly small-sized plaques.;Vaccines were prepared from the 8th and the 9th viral passages of suspension and monolayer BHK cells, respectively. The virus inactivation was combined with 3 mM ethylenemine for 72 hours at 25(DEGREES)C. The antigen mass of the two vaccines was made equal with the CF estimation method. Two groups of steers, consisting of six animals each, were vaccinated with one or the other oil adjuvanted vaccines. Subsequently, the animals were temperatured and examined for FMD lesions for 14 days. The results showed that one out of six steers vaccinated with the monolayer cells-produced virus became susceptible to challenge virus. On the other hand, all the steers vaccinated with the suspension cells-produced vaccine were protected. The mean neutralizing antibody titers of the two groups of animals also did not significantly vary both in the pre and post challenge sera. However, anti-virus infection associated antigen was found only in the post challenge sera of two animals from the suspension vaccine groups and four from the monolayer vaccine group.;In conclusion, no difference of immunogenicity was demonstrated in steers between FMD vaccines formulated from type O(,1) virus grown in suspension or monolayer BHK cells. The antigenicity and the plaque characteristic of the virus are influenced by the replicative systems.;Foot-and-mouth disease virus, O(,1), obtained from infected bovine tongue epithelium was serially passaged 10 times each in mice, guinea pigs, suspended and monolayer BHK cells. Antisera were produced to the 8th passage for the suspension virus and to 10th passage for each of the remaining viruses. All the antisera were fractionated to the 140S specific and the 12S x 140S reactive sera on a 12S protein subunit affinity chromatography column. With the use of various serologic techniques these antisera were applied in the antigenic analysis of the viruses. The results of neutralization and plaque reduction tests showed that the viruses were antigenically different. In the immunodiffusion test, virus produced in the monolayer cells was differentiated by the homologous antisera. The neutralization kinetics test on the other hand, could discriminate viruses of the two BHK cell culture systems from the other viruses but failed to differentiate between the two. |
