Comparison of the infectivity of Babesia bovis, Babesia bigemina and Anaplasma centrale for cattle after cryopreservation in either dimethylsulphoxide (DMSO) or polyvinylpyrrolidone (PVP).

摘要

The suitability of PVP with a molecular weight of 40 000 as an alternative cryoprotectant to DMSO for preparation of Babesia and Anaplasma stabilates used in the production of vaccine was evaluated. Vaccine strains of B. bovis, B. bigemina and A. centrale were collected from the blood of 3 splenectomized calves and stabilates prepared within 30 min of blood collection using DMSO or PVP as cryoprotectant. The stabilates were stored in liquid nitrogen and had final parasite counts per ml of 170X106 for B. bovis, 5X106 for B. bigemina and 160X106 for A. marginale. Following later thawing, the infectivity of the stabilates was tested on uninfected cattle. All animals showed patent infections, and there was no significant difference in the prepatent periods for either of the Babesia spp. or Anaplasma prepared using DMSO or PVP. The suitability of stabilates prepared using PVP for routine vaccine production was also assessed in a 34-month trial using 33 splenectomized vaccine donor calves. Again, all animals became infected and there was no significant difference in prepatent periods. It is concluded that PVP is as effective as DMSO for use as a cryoprotectant for storing B. bovis, B. bigemina and A. centrale, but has the advantage of being less toxicto the parasites and to the cattle.