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Definition of the range and distribution of human immunodeficiency virus macrophage tropism using PCR-based
Abstract:
The tropism of human immunodeficiency virus (HIV) for macrophages (m phi) is a well recognized phenomenon, but the range and distribution of m phi-tropic phenotypes have not been defined by quantitative means. This study uses a PCR-based infectivity assay to derive an index of m phi tropism for several common strains of HIV. The results show that m phi tropism varies over about six orders of magnitude and that the most m phi-tropic strains have a higher infectivity for m phi than for peripheral blood lymphocytes. Strains were distributed throughout this range, suggesting that m phi tropism is a continuously variable phenotypic property. Although the degree of tropism was strongly influenced by the mode of isolation and propagation of virus strains, there was no evidence for the existence of distinct m phi-tropic or non-m phi-tropic phenotypes. Finally, the tropism of two selected strains was found to be determined by an early step in replication, probably virus entry.
Insights
Human immunodeficiency virus (HIV) shows variable tropism for macrophages. This study quantifies HIV macrophage tropism, revealing a continuous spectrum of infectivity rather than distinct phenotypes.
Area of Science:
- Virology
- Immunology
Background:
- Human immunodeficiency virus (HIV) exhibits tropism for macrophages (m phi), a key cellular target.
- Quantitative data on the range and distribution of macrophage-tropic HIV phenotypes are limited.
Purpose of the Study:
- To quantitatively define the range and distribution of macrophage tropism among common HIV strains.
- To investigate whether distinct macrophage-tropic or non-tropic HIV phenotypes exist.
Main Methods:
- Utilized a PCR-based infectivity assay to generate an index of macrophage tropism for various HIV strains.
- Assessed infectivity of HIV strains for both macrophages and peripheral blood lymphocytes.
Main Results:
- Macrophage tropism for HIV strains varied significantly, spanning six orders of magnitude.
- The most macrophage-tropic strains demonstrated higher infectivity for macrophages than for peripheral blood lymphocytes.
- HIV tropism was found to be a continuously variable phenotypic property, not falling into distinct categories.
- Virus isolation and propagation methods influenced the degree of tropism observed.
Conclusions:
- HIV macrophage tropism exists on a continuous spectrum, with no evidence of discrete tropism categories.
- Early replication steps, likely including virus entry, determine the tropism of selected HIV strains.