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Dissertation
Genetic effects on host virus interactions: antigenic variation during E55+ MuLV infection of inbred strains of mice and the virus neutralizing antibody response
Doctor of Philosophy (Ph.D.), Medical College of Pennsylvania and Hahnemann University
Apr 2000
DOI:
https://doi.org/10.17918/00007132
Abstract
E55+MuLV is a chronic murine leukemia virus (MuLV) that exhibits strain specific differences in its ability to cause a T-cell lymphoma in immunocompetent adult mice. All strains of mice resolve the acute infection caused by E55+ MuLV and establish a low-level persistent infection. Some strains, known as long-term nonprogressors (LTNP), maintain this low-level persistent infection for at least two years. Other strains, known as progressors, experience a rise in virus levels around 4-6 months post-infection concordant with the development of a T-cell lymphoma. The goal of the studies presented in this thesis was to identify differences in virus-host interactions between progressor and long-term nonprogressor (LTNP) strains responsible for their respective abilities in maintaining the low-level persistent E55+ MuLV infection. In E55+ MuLV infected adult immunocompetent BALB.K progressors, a variant virus (E55- MuLV) emerges and is present in all virus-induced tumors isolated. The LTR regions of both E55+ and E55- MuLV were sequenced to determine if alterations were present that could be responsible for changes in virus replication rate, tissue tropism, or disease specificity. No alterations in LTR sequence were noted. Sequence analysis of both the gag and pol genes (the env was previously characterized) was performed to determine if significant changes were present that could be responsible for loss of recognized immune epitopes. Two nucleotide changes resulting in a single amino acid difference between the gag genes and six nucleotide changes resulting in three amino acid differences between the pol genes were identified. A consistent alteration in the env region resulting from a recombination event with an endogenous MuLV is present in E55- MuLV. This alteration has been shown to be associated with an inability to be neutralized by serum from E55+ MuLV infected progressor BALB.K mice. B10.BR LTNP, on the other hand, are able to neutralize E55- MuLV when infected with E55+ MuLV. To demonstrate the importance of neutralizing antibodies in establishment and maintenance of low-level persistent infection with E55+ MuLV, [mu]MT mice (B-cell deficient) were employed in two studies. Both studies demonstrated that [mu]MT mice were unable to resolve the acute phase of infection with E55+ MuLV. Furthermore, one of the studies demonstrated that passive antibody transfer from immunized immunocompetent C57B1/6 was sufficient to confer the ability to resolve acute phase infection in [mu]MT mice. It was next decided to pursue the genetic basis underlying the difference in ability between BALB.K and B10.BR to neutralize E55- MuLV when infected with E55+ MuLV. To determine whether this ability was due to a dominantly inherited trait, (B10.BR x BALB.K)F1 mice were bred, infected with E55+ MuLV at six weeks of age, and sacrificed 8 weeks later. In vitro neutralization assays were then performed with serum from these mice to determine their ability to neutralize E55- MuLV. The results demonstrated that 100% of these mice neutralize E55- MuLV (hence the trait is dominantly inherited). (B10.BR x BALB.K)F1 x BALB.K backcross mice were then bred to establish how many loci were responsible for the trait. Backcross mice were infected with E55+ MuLV at six weeks of age, and serum was harvested 8 weeks later for use in in vitro neutralization assays. It was determined that 34/46 (73.9%) of these mice generated neutralizing antibodies against E55- MuLV, indicating that two loci are responsible for the trait Utilizing microsatellite mapping, a candidate for one of these loci was identified on chromosome 10 (D1OMit117, LOD=2.37, p=9.5 x 10⁻⁴). At present no known genes which map to this region appear to be candidates. Furthermore, it was noted that a sex difference existed in antibody production such that male mice produced a response both more frequently, and at a higher titer (LOD=3.7, p=3.8 x 10⁻⁵).
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Details
- Title
- Genetic effects on host virus interactions
- Creators
- Jason Halegoua
- Contributors
- Kenneth J. Blank (Advisor) - Temple University
- Awarding Institution
- Medical College of Pennsylvania and Hahnemann University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Medical College of Pennsylvania and Hahnemann University; Philadelphia, Pennsylvania
- Number of pages
- x, 120 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- School of Medicine (1993-1996, 1998-2002); Medical College of Pennsylvania and Hahnemann University (1993-1996, 1998-2002)
- Other Identifier
- 991021888053004721