[Extraction and freeze-drying of herpes virus C3-1 isolated from turkeys]

Possibilities for producing dried preparations of turkey herpes virus C3-1 by use of various ultra-sound desintegrator-systems and different ways of processing the cell suspensions containing the virus were studied. It was established that cell-less virus of a 1.5 to 2 log smaller quantity than the initial virus containing cell suspension can be produced by ultrasound generator with an indirect action -- a vibrating membrane, which transmits the impulses through a liquid medium and the container's walls on the object. The use of a generator with direct action -- titanic probe placed into the suspension results in an insignificant loss and in some cases even leads to higher titer. In the process of freeze drying the protective media SPGA, 5% pepton and 5% horse serum produce almost equal results. Highest dried virus yield was produced by lyophilization of entire (without centrifugal separation) ultrasounded cell suspension. In such cases the titer of the freeze-drying virus was by 0.2-0.4 log higher than the initial cell virus determined after the microplate method. The authors are of the opinion that titration by this method does not give an exact criterion for comparison of virus content in frozen cell and freeze-dried preparations. A proper protection against Marek's disease was established in laboratory and terrain experiments with chickens following immunization by freze-dried preparations of the strain C3-1 (losses were reduced 3-4 times). An immunization dose of 2000 POU lyophilized virus is recommended for practical use.