Scrambling of the amino acids within the transmembrane domain of Vpu results in a simian-human immunodeficiency virus (SHIVTM) that is less pathogenic for pig-tailed macaques.
Previous studies have shown that the transmembrane (TM) domain of the subtype B Vpu enhances virion release from cells and some studies have shown that this domain may form an oligomeric structure with properties of an ion channel. To date, no studies have been performed to assess the role of this domain in virus pathogenesis in a macaque model of disease. Using a pathogenic molecular clone of simian human immunodeficiency virus (SHIVKU-1bMC33), we have generated a novel virus in which the transmembrane domain of the Vpu protein was scrambled but maintained hydrophobic in nature (SHIVTM), which presumably would disrupt any ion channel TM properties of this protein. Vectors expressing the Vpu as a fusion protein with the enhanced green fluorescent protein (VpuTMEGFP) indicate that it was transported to the same intracellular compartment as the unmodified Vpu protein but did not down-regulate cell surface expression of CD4. To assess the pathogenicity of SHIVTM, three pig-tailed macaques were inoculated with the SHIVTM and monitored for 6-8 months for CD4+ T cell levels, viral loads and the stability of the sequence of the vpu gene. Our results indicated that unlike the parental SHIVKU-1bMC33, inoculation of macaques with SHIVTM did not cause a severe CD4+ T cell loss over the course of their infections. Sequence analysis of the vpu gene analyzed from sequential PBMC samples derived from macaques revealed that the scrambled TM was stable during the course of infection. At necropsy, examination of tissues revealed low viral loads and none of the pathology commonly observed in lymphoid and non-lymphoid tissues following inoculation with the pathogenic parental SHIVKU-1bMC33 virus. Thus, these results show for the first time that the TM domain of Vpu contributes to the pathogenicity of SHIVKU-1bMC33 in pig-tailed macaques.
Department of Anatomy and Cell Biology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA.
David R
DR
Hout
Melissa L
ML
Gomez
Erik
E
Pacyniak
Lisa M
LM
Gomez
Sarah H
SH
Inbody
Ellyn R
ER
Mulcahy
Nathan
N
Culley
David M
DM
Pinson
Michael F
MF
Powers
Scott W
SW
Wong
Edward B
EB
Stephens
D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology / Q000821:virology*; D000818:Animals; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D015536:Down-Regulation; D015497:HIV-1 / Q000235:genetics*; D054298:Human Immunodeficiency Virus Proteins; D006801:Humans; D008198:Lymph Nodes / Q000821:virology; D008254:Macaca nemestrina; D017434:Protein Structure, Tertiary / Q000502:physiology; D016865:Reassortant Viruses / Q000472:pathogenicity / Q000502:physiology*; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000472:pathogenicity*; D054334:Viral Regulatory and Accessory Proteins / Q000502:physiology*; D014774:Virulence; D014779:Virus Replication; D000086082:Viroporin Proteins
D054298:Human Immunodeficiency Virus Proteins; D054334:Viral Regulatory and Accessory Proteins; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins