HIV p55/17

HIV p55/17 Full Name

Human Immunodeficiency Virus Type 1 p17; Human Immunodeficiency Virus Type 1 p55

HIV p55/17 Introduction

HIV-1 p55, commonly referred to as the Gag polyprotein precursor, is a 55 kDa polypeptide that plays a central role in viral assembly and maturation. During virion formation, p55 is proteolytically processed by the HIV-1 protease into mature structural components, including matrix p17 (MA), capsid p24 (CA), nucleocapsid p7 (NC), and the p6/spacer peptides, with some schemata additionally describing p15/p24 cleavage products. This proteolytic cascade is essential for the proper assembly of infectious virions and has been extensively characterized in foundational studies spanning several decades. Monoclonal antibody mapping and biochemical analyses demonstrate the relationship between the precursor and its mature products, reinforcing the centrality of p55 in virion architecture. Beyond structural roles, p55 serves as a substrate for host and viral factors that regulate budding, assembly, and particle maturation, highlighting its dual importance in both virion formation and as a key antigenic target in vaccine design. Studies show that interference with p55 processing, including the use of protease inhibitors such as pepstatin A, prevents the maturation of p17 and p24 and blocks virion infectivity, illustrating that p55 processing is indispensable for productive viral replication.

The immunological relevance of p55 Gag is well-documented, particularly in the context of cytotoxic T lymphocyte (CTL) responses. p55-directed vaccines and virus-like particles (VLPs) have been shown to elicit broad and durable CD8+ T cell responses in non-human primates and murine models, with multiple epitopes across p55 and its processed components contributing to long-lived immunity. The structural form of Gag is a critical determinant of immunogenicity: particulate Gag in VLPs consistently induces stronger cellular responses than soluble or intracellular forms, emphasizing the importance of presenting Gag in a quasi-native context to optimize CTL activation. In addition, p55 interacts with viral envelope components, including gp41, and associates with lipid rafts (detergent-resistant membranes), which influence proper incorporation of Env into budding virions. Mutations in the MA/p17 domain of p55 can disrupt envelope association and impair particle formation, demonstrating the functional interplay between Gag structural domains and viral envelope determinants. These observations collectively illustrate that p55 not only drives assembly but also orchestrates the precise structural organization needed for immunogenicity and virion integrity.

Beyond its canonical role in virion assembly, p55 exhibits broader interactions with host cellular pathways. In vitro studies indicate that p55 or Gag-derived fragments can modulate osteoblast differentiation and mesenchymal stem cell function via signaling pathways such as RUNX2/PPARγ, suggesting potential systemic effects of Gag proteins outside classical immune or virological contexts. While these findings derive primarily from cell line models, they point to a capacity of Gag to interact with diverse host proteins and influence cellular biology, which may contribute to certain complications observed in HIV-infected individuals. Taken together, HIV-1 p55 Gag is central to the viral life cycle as the precursor of essential structural proteins, a potent immunogen capable of eliciting broad CTL responses, and a modulator of host-cell interactions. Its processing by HIV protease, structural interactions with Env, and immunogenic properties underscore its importance in both fundamental HIV biology and applied strategies for vaccine design and therapeutic intervention.

Alternate Names for HIV p55/17

HIV1 p17 + p55; HIV; Human immunodeficiency virus; Lentivirus; HIV1 p17/55; HIV1 p17; HIV1 p55; Human Immunodeficiency Virus Type 1 p17; Human Immunodeficiency Virus Type 1 p55

• 1. Kalams S., et al. Focusing HIV-1 Gag T cell responses to highly conserved regions by DNA vaccination in HVTN 119. JCI Insight. 2024;9(18).
  2. Yuan Y., et al. HIV-1 p55-gag protein induces senescence of human bone marrow mesenchymal stem cells and reduces their capacity to support expansion of hematopoietic stem cells in vitro. Cell Biology International. 2017;41(9):969-981.
  3. Zhang S., et al. Membrane-Active Sequences within gp41 Membrane Proximal External Region (MPER) Modulate MPER-Containing Peptidyl Fusion Inhibitor Activity and the Biosynthesis of HIV-1 Structural Proteins. PLOS One. 2015;10(7):e0134851.
  4. Zhang Z., et al. Characterization and epitope mapping of a panel of monoclonal antibodies against HIV-1 matrix protein. Biotechnology and Applied Biochemistry. 2018;65(6):807-815.