Diverse viral glycoproteins as well as CD4 co-package into the same human immunodeficiency virus (HIV-1) particles.
BACKGROUND
Retroviruses can acquire not only their own glycoproteins as they bud from the cellular membrane, but also some cellular and foreign viral glycoproteins. Many of these non-native glycoproteins are actively recruited to budding virions, particularly other viral glycoproteins. This observation suggests that there may be a conserved mechanism underlying the recruitment of glycoproteins into viruses. If a conserved mechanism is used, diverse glycoproteins should localize to a single budding retroviral particle. On the other hand, if viral glycoproteins have divergent mechanisms for recruitment, the different glycoproteins could segregate into different particles.


RESULTS
To determine if co-packaging occurs among different glycoproteins, we designed an assay that combines virion antibody capture and a determination of infectivity based on a luciferase reporter. Virions were bound to a plate with an antibody against one glycoprotein, and then the infectivity was measured with cells that allow entry only with a second glycoprotein. We tested pairings of glycoproteins from HIV, murine leukemia virus (MLV), Rous sarcoma virus (RSV), vesicular stomatitis virus (VSV), and Ebola virus. The results showed that glycoproteins that were actively recruited into virions were co-packaged efficiently with each other. We also tested cellular proteins and found CD4 also had a similar correlation between active recruitment and efficient co-packaging, but other cellular proteins did not.


CONCLUSIONS
Glycoproteins that are actively incorporated into HIV-1 virions are efficiently co-packaged into the same virus particles, suggesting that the same general mechanism for recruitment may act in many viruses.
Devon A
DA
Gregory
Grace Y
GY
Olinger
Tiffany M
TM
Lucas
Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, MO, USA. marcjohnson@missouri.edu.
Marc C
MC
Johnson
D015704:CD4 Antigens / Q000378:metabolism*; D002460:Cell Line; D006023:Glycoproteins / Q000378:metabolism*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D014764:Viral Proteins / Q000378:metabolism*; D019065:Virus Assembly
D015704:CD4 Antigens; D006023:Glycoproteins; D014764:Viral Proteins