Human Immunodeficiency Virus
Human Immunodeficiency Virus (HIV) exists in two distinct types, HIV type 1 (HIV-1) and HIV type 2 (HIV-2). The predominant virus worldwide is HIV-1, whilst HIV-2 is geographically restricted to West Africa, and is less infectious and causes slower disease progression.
HIV-1 viruses may be further divided into groups, being M, N, O and P. The HIV-1 group M viruses predominate and are responsible for the AIDS pandemic. Within the M group of HIV-1 there are a number of genetically distinct sub-types (also known as clades). Different subtypes can also combine genetic material to form a hybrid virus or “circulating recombinant form (CRF)”. Subtype B is the most common in the Americas and Western Europe, whilst subtype C is the predominant form in Africa and India. Most research has been carried out into subtype B, although it accounts for only around 12% of infections worldwide.
HIV GP120 protein
HIV GP120 protein (or gp120) is the name of the glycoprotein which forms the spikes sticking out of a HIV virus particle. HIV gp120 protein is essential for virus entry into cells as it plays a vital role in seeking out specific cell surface receptors for entry. Three gp120s, bound as heterodimers to a transmembrane glycoprotein, gp41, are thought to combine in a trimer to form the envelope spike, which is involved in virus-cell attachment. Approximately 50% of the mass of HIV gp120 protein is due to glycosylation, the high level of which may prevent gp120 from being recognised by the human immune response. gp120 binds to the human cell surface antigen CD4, which is primarily expressed by Helper T lymphocytes and monocytes/macrophages.
This recombinant HIV gp120 protein is derived from a CRF first isolated in China, which is a combination of subtypes B and C. It is derived from the env. gene of HIV-1 strain CN54 gp160 (GenBank Gene Ac. # AX149771, Thr27-Arg498) fused with a polyhistidine tag at the C-terminus, and has a calculated MW of 53.8 kDa. The protein migrates at 80-110 kDa in reducing SDS-PAGE due to glycosylation
****SHIPPING AND STORAGE NOTIFICATION: This recombinant protein has been lyophilised to maximise stability. It is shipped at ambient temperature, and may be stored for up to 1 year at 4C prior to reconstitution. Following reconstitution it should be stored at -80C. Extensive stability tests have shown no negative effects on antigen performance for 7 days of shipping at ambient temperature.