| | | Document Type | : | Latin Dissertation | | Language of Document | : | English | | Record Number | : | 53724 | | Doc. No | : | TL23678 | | Call number | : | 3220023 | | Main Entry | : | Devi Prasanna Patnayak | | Title & Author | : | Live attenuated vaccines against avian pneumovirusDevi Prasanna Patnayak | | College | : | University of Minnesota | | Date | : | 2006 | | Degree | : | Ph.D. | | student score | : | 2006 | | Page No | : | 154 | | Abstract | : | Avian pneumovirus (APV) is increasingly recognized as an important respiratory pathogen of turkeys causing a rapidly spreading disease of all ages. Because of the significant economic impact of the disease, there has been an urgent and critical need to develop effective vaccines and vaccination strategies against APV strains prevalent in the United States. Researchers in the U.S. initially worked on the development of killed vaccines but because of their low efficacy, efforts have now been devoted to the development of live, attenuated vaccines. Earlier, our laboratory reported on the development of an attenuated vaccine by passaging a local isolate (APV/MN-1a) in vitro for 41 passages (named P41). Because of its residual pathogenicity, despite being protective, we further passaged this strain for an additional 22 passages and named it as P63. In the present work, safety and efficacy of this attenuated virus was evaluated. In another approach, cold adaptation was undertaken for developing another live vaccine. Both vaccines were evaluated for their efficacy in turkeys following administration by different routes of inoculation. The duration of immunity with both vaccines was also studied and efforts were made to evaluate possibilities of increasing titers of these vaccines in cell cultures. The results of experimental evaluation indicated that both vaccines were protective in 4-week old turkeys at two different doses. No reversion to virulence was observed when P63 was passaged six successive times in vivo. It was found to be protective following aerosol, oculo-nasal and oral routes of inoculation. The cold adapted vaccine was administered at 1 day of age by all three routes. Although the vaccine was found to be protective, it did produce mild clinical signs in some birds following vaccination. Both vaccines conferred protection for up to 14 weeks post vaccination following administration of a single dose. In another study, both vaccine strains grew to high titers in BGM-70 cells in addition to commonly used Vero cells. Since vaccination is the major method in the control of APV, efforts should continue to improve the current vaccines and to develop newer, more effective vaccines. | | Subject | : | Biological sciences; Avian pneumovirus; Live-attenuated vaccines; Pneumovirus; Vaccines; Veterinary services; Anatomy & physiology; Animals; 0433:Animals; 0778:Veterinary services; 0433:Anatomy & physiology | | Added Entry | : | S. M. Goyal | | Added Entry | : | University of Minnesota |
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