Incorporation of high levels of chimeric human immunodeficiency virus envelope glycoproteins into virus-like particles.
The human immunodeficiency virus (HIV) envelope (Env) protein is incorporated into HIV virions or virus-like particles (VLPs) at very low levels compared to the glycoproteins of most other enveloped viruses. To test factors that influence HIV Env particle incorporation, we generated a series of chimeric gene constructs in which the coding sequences for the signal peptide (SP), transmembrane (TM), and cytoplasmic tail (CT) domains of HIV-1 Env were replaced with those of other viral or cellular proteins individually or in combination. All constructs tested were derived from HIV type 1 (HIV-1) Con-S DeltaCFI gp145, which itself was found to be incorporated into VLPs much more efficiently than full-length Con-S Env. Substitution of the SP from the honeybee protein mellitin resulted in threefold-higher chimeric HIV-1 Env expression levels on insect cell surfaces and an increase of Env incorporation into VLPs. Substitution of the HIV TM-CT with sequences derived from the mouse mammary tumor virus (MMTV) envelope glycoprotein, influenza virus hemagglutinin, or baculovirus (BV) gp64, but not from Lassa fever virus glycoprotein, was found to enhance Env incorporation into VLPs. The highest level of Env incorporation into VLPs was observed in chimeric constructs containing the MMTV and BV gp64 TM-CT domains in which the Gag/Env molar ratios were estimated to be 4:1 and 5:1, respectively, compared to a 56:1 ratio for full-length Con-S gp160. Electron microscopy revealed that VLPs with chimeric HIV Env were similar to HIV-1 virions in morphology and size and contained a prominent layer of Env spikes on their surfaces. HIV Env specific monoclonal antibody binding results showed that chimeric Env-containing VLPs retained conserved epitopes and underwent conformational changes upon CD4 binding.
Wang
Bao-Zhong
BZ
Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA 30322, USA.
Liu
Weimin
W
Kang
Sang-Moo
SM
Alam
Munir
M
Huang
Chunzi
C
Ye
Ling
L
Sun
Yuliang
Y
Li
Yingying
Y
Kothe
Denise L
DL
Pushko
Peter
P
Dokland
Terje
T
Haynes
Barton F
BF
Smith
Gale
G
Hahn
Beatrice H
BH
Compans
Richard W
RW
D000818:Animals; D000956:Antigens, Viral; D015704:CD4 Antigens / Q000378:metabolism; D006678:HIV / Q000737:chemistry / Q000648:ultrastructure; D006801:Humans; D010446:Peptide Fragments / Q000235:genetics; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D011995:Recombination, Genetic; D014771:Virion / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D054299:env Gene Products, Human Immunodeficiency Virus / Q000235:genetics* / Q000378:metabolism*
D000956:Antigens, Viral; D015704:CD4 Antigens; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D054299:env Gene Products, Human Immunodeficiency Virus