Accession Number:

AD0840453

Title:

ATTENUATION OF A VIRULENT FOWL POX VIRUS IN CELL CULTURES AND PROPERTIES OF THE ATTENUATED VIRUS,

Descriptive Note:

Corporate Author:

ARMY BIOLOGICAL LABS FREDERICK MD

Personal Author(s):

Report Date:

1968-06-07

Pagination or Media Count:

20.0

Abstract:

Virulent fowl pox virus was attenuated by continuous passage in chick embryo fibroblast cultures, 300 to 350 passages being necessary. The course of attenuation is described. The attenuated virus produces no clinical symptoms when injected cutaneously and parenterally into 14-day-old chicks and its virulence for day-old chicks is also markedly reduced in that only 15 develop generalized infection. Uninoculated animals do not develop the disease by contact with inoculated ones. Its immunizing properties are as good as those of the fully virulent H strains. After cutaneous inoculation there is a general immunity of 100 and a marked cutaneous immunity also. The good immunizing effect in day-old chicks was particularly striking and the percentage of cutaneous immunity was larger among these after parenteral inoculation than in older birds. Its properties make the attenuated culture virus particularly suitable for fowl pox vaccines. In respect of harmlessness it approaches that of the T strains and in effectiveness it approaches the H strains. The production of harmless H strains makes the argument about whether to use H or T strains in vaccination unnecessary. Author

Subject Categories:

  • Animal Husbandry and Veterinary Medicine
  • Microbiology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE