The Role of APOBEC3 in Controlling Retroviral Spread and Zoonoses

FieldValue
dc.contributor.authorRosales Gerpe, María Carla
dc.date.accessioned2014-08-21T17:26:59Z
dc.date.available2014-08-21T17:26:59Z
dc.date.created2014
dc.date.issued2014
dc.identifier.urihttp://hdl.handle.net/10393/31484
dc.identifier.urihttp://dx.doi.org/10.20381/ruor-6320
dc.description.abstractAPOBEC3 (A3) proteins are a family of host-encoded cytidine deaminases that protect against retroviruses and other viral intruders. Retroviruses, unlike other viruses, are able to integrate their genomic proviral DNA within hours of entering host cells. A3 proteins hinder retroviral infectivity by editing retroviral replication intermediates, as well as by inhibiting retroviral replication and integration through deamination-independent methods. These proteins thus constitute the first line of immune defense against endogenous and exogenous retroviral pathogens. The overall goal of my Master's project was to better understand the critical role A3 proteins play in restricting inter- and intra-host transmission of retroviruses. There are two specific aspects that I focused on: first, investigating the role of mouse APOBEC3 (mA3) in limiting the zoonotic transmission of murine leukemia retroviruses (MLVs) in a rural environment; second, to identify the molecular features in MLVs that confer susceptibility or resistance to deamination by mA3. For the first part of my project, we collected blood samples from dairy and production cattle from four different geographical locations across Canada. We then designed a novel PCR screening strategy targeting conserved genetic regions in MLVs and Mouse Mammary Tumor Virus (MMTV) and MMTV-like betaretroviruses. Our results indicate that 4% of animals were positive for MLV and 2% were positive for MMTV. Despite crossing the species barrier by gaining entry into bovine cells, our study also demonstrates that the bovine A3 protein is able to potently inhibit the spread of these murine retroviruses in vitro. The next question we asked was whether mA3 could also mutate and restrict murine endogenous retroviruses and thereby partake in limiting zoonotic transmission. Moloney MLV and AKV MLV are two highly homologous murine gammaretroviruses with opposite sensitivities to restriction by mA3: MoMLV is resistant to restriction and deamination while AKV is sensitive to both. Design of MoMLV/AKV hybrid viruses enabled us to map the region of mA3 resistance to the region encoding the glyco-Gag accessory protein. Site-directed mutagenesis then allowed us to correlate the number of N-linked glycosylation sites with the level of resistance to deamination by mA3. Our results suggest that Gag glycosylation is a possible viral defence mechanism that arose to counteract the evolutionary pressure imposed by mA3. Overall, my projects show the important role A3 proteins play in intrinsic immunity, whether defending the host from foreign retroviral invaders or endogenous retroviral foes.
dc.language.isoen
dc.publisherUniversité d'Ottawa / University of Ottawa
dc.subjectAPOBEC3
dc.subjectdeamination
dc.subjectrestriction factor
dc.subjectHIV
dc.subjectretrovirus
dc.subjectaccessory protein
dc.subjectgammaretrovirus
dc.subjectglycosylation
dc.subjectglyco-Gag
dc.subjectzoonosis
dc.subjectN-linked glycosylation
dc.subjectretroviral transmission
dc.subjectcattle
dc.subjectbovine
dc.subjectmice
dc.subjectmurine
dc.subjectendogenous retroviruses
dc.subjectexogenous retroviruses
dc.subjectMoloney murine leukemia virus
dc.subjectAkv murine leukemia virus
dc.subjectFriend murine leukemia virus
dc.subjectXenotropic Murine leukemia virus-Related Virus
dc.subjectXMRV
dc.subjectMouse mammary tumor virus
dc.subjectMMTV
dc.subjectcancer
dc.subjectcytidine deaminases
dc.subjectA3G
dc.subjectmouse APOBEC3
dc.subjectmA3
dc.subjecthypermutation
dc.subjectinhibition
dc.subjectretroviral spread
dc.subjectfitness
dc.titleThe Role of APOBEC3 in Controlling Retroviral Spread and Zoonoses
dc.typeThesis
dc.faculty.departmentBiochimie, microbiologie et immunologie / Biochemistry, Microbiology and Immunology
dc.contributor.supervisorLanglois, Marc-André
dc.degree.nameMSc
dc.degree.levelmasters
dc.degree.disciplineMédecine / Medicine
thesis.degree.nameMSc
thesis.degree.levelMasters
thesis.degree.disciplineMédecine / Medicine
uottawa.departmentBiochimie, microbiologie et immunologie / Biochemistry, Microbiology and Immunology
CollectionThèses, 2011 - // Theses, 2011 -

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