All ETDs from UAB

Advisory Committee Chair

John C Kappes

Advisory Committee Members

Robinna Lorenz

Zdenek Hel

Olaf Kutsch

Phillip Smith

Peter Prevelige

Document Type

Dissertation

Date of Award

2011

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Heterosexual transmission of human immunodeficiency virus type&ndash1 (HIV&ndash1) accounts for the majority of infections worldwide, with women representing the larger percentage of infected individuals. The events leading to the transmission of HIV&ndash1 at mucosal surfaces are not well defined. Based on the observations that transmitted viruses nearly exclusively utilize the CCR5 coreceptor, and that in 80% of heterosexual transmissions a single virus variant establishes infection, there appears to be a selection mechanism that allows only a subset of viruses to be transmitted. This genetic bottleneck suggests that transmitted viruses may possess specific phenotypic and/or genotypic properties that allow for their preferential transmission. Elucidating the biological characteristics of these viruses may be instrumental in developing an efficacious vaccine. Utilizing viral sequences determined by single genome amplification (SGA), we generated infectious molecular clones (IMCs) of 10 full&ndashlength clade B transmitted viral genomes. To directly examine determinants in Env, we also generated a Renilla luciferase reporter virus that expresses viral env genes in cis (Env&ndashIMC&ndashLucR viruses). Transmitted viruses were compared to &ldquoprototypic&rdquo macrophage&ndashtropic viruses (BaL, SF162 and YU&ndash2), which are commonly utilized in studies of HIV&ndash1 transmission, for infectivity and replication in primary CD4+ T lymphocytes, monocyte&ndashderived macrophages (MDM) and vaginal mucosal cells. Transmitted viruses replicated to high titers in CD4+ T lymphocyte cultures, with similar kinetics to control viruses. However, in MDM, their replication was 10 to 100&ndashfold lower than that of the controls. In both CD4+ T lymphocytes and MDM, Env&ndashIMC&ndashLucR viruses replicated similarly to their cognate full&ndashlength virus, indicating the low macrophage tropism phenotype observed for the transmitted viruses is due to virus&ndashspecific molecular determinants in Env. Additionally, MDM infected with transmitted viruses contained significantly less reverse&ndashtranscribed cDNA compared to cells infected with control viruses, indicating the phenotype manifests early in the virus life cycle. In vaginal mucosal cells, both transmitted and control viruses were infectious, and flow cytometric analysis identified HIV&ndash1 antigen positive T lymphocytes, dendritic cells and macrophages in the cultures. These results indicate that transmitted viruses are not highly tropic for MDMs and further analysis will reveal whether transmitted viruses possess tropisms for specific vaginal mucosal cells.

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