Molecular Characterization of Fowlpox Virus Isolates and Evaluation of Recombinant Vaccines Generated for Protection Against Fowlpox and Reticuloendotheliosis
Singh, Pratik
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/87121
Description
Title
Molecular Characterization of Fowlpox Virus Isolates and Evaluation of Recombinant Vaccines Generated for Protection Against Fowlpox and Reticuloendotheliosis
Author(s)
Singh, Pratik
Issue Date
2002
Doctoral Committee Chair(s)
Deoki N. Tripathy
Department of Study
Veterinary Clinical Medicine
Discipline
Veterinary Clinical Medicine
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Animal Pathology
Language
eng
Abstract
Fowlpox, an economically important disease of chickens, is prevented by routine immunization of birds in endemic areas with an attenuated live Fowlpox virus (FPV) vaccine. However, despite this precaution, outbreaks of Fowlpox still continue to occur in vaccinated chickens suggesting a lack of adequate protection by current vaccines. To determine the probable causes for these outbreaks, field isolates were compared with the vaccine strains. Antigenic variation amongst the strains was evident in immunoblotting with polyclonal and monoclonal antibodies. Biological differences were detected by the prolonged persistence and appearance of secondary lesions with field strains as well as variation in their protective ability. The contrasting difference noted between field isolates and vaccine strains was, the retention of variable lengths of an avian retrovirus sequences integrated in their genomes. Whereas only remnants of the long terminal repeats (LTR) of reticuloendotheliosis virus (REV) were detected in the genomes of the vaccine strains, either these partial LTR or nearly intact proviral copies of REV were found in the genomes of all field isolates so far examined. Since integrated REV can be released from the FPV genome and cause immuno-suppression, this symbiotic relationship presumably benefits both viruses by maintaining REV as part of FPV and enhancing the pathogenicity of FPV. In this regard, removal of REV from the genome of a field strain of FPV coincided with decreased virulence of the altered virus for the chickens. However, REV associated suppression of lymphocyte response to mitogen stimulation due to REV infection was not detected, suggesting that other immuno-suppressive mechanisms are involved. Since, under natural conditions, chickens become dually infected with both FPV and REV, a FPV recombinant expressing the REV envelop gene was generated. In current study, chickens immunized with the recombinant were protected against challenge both FPV and REV. This is the first study on (i) the molecular analyses of field strains of FPV isolated from outbreaks in previously vaccinated chicken flocks (ii) the role of integrated REV in the virulence of FPV and (iii) generation of the first FPV strain lacking any integrated REV sequences.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
