Anti-HIV Activity of Lung SRCR (gp-340) in Saliva

描述（由申请人提供）：虽然从HIV阳性受试者获得的唾液通常对HIV RNA序列呈PCR阳性，但从口腔样本中培养病毒是极其困难的。再加上流行病学观察表明艾滋病毒很少经口传播，现在人们普遍认为唾液中含有灭活病毒的因素。我们之前证明了大多数个体的唾液能够在体外特异性地抑制HIV-1感染。研究人员利用具有高抗hiv活性个体的下颌和腮腺唾液样本，鉴定并纯化了两种高分子量唾液凝集素（SAG）和黏液蛋白（MG2）。这两种纯化的糖蛋白在体外唾液浓度下抑制HIV-1感染。我们随后证明了抑制机制涉及唾液蛋白与gp120的结合，以及随后gp120从病毒粒子中脱落。

DESCRIPTION (provided by applicant): While saliva obtained from HIV positive subjects is often PCR positive for HIV RNA sequences, it is extremely difficult to culture virus from oral samples. Coupled with the epidemiologic observations that HIV is rarely orally transmitted, it is now widely believed that saliva contains factors that inactivate the virus. We previously demonstrated that saliva from most individuals was able to specifically inhibit HIV-1 infection in vitro. Submandibular and parotid saliva samples from individuals demonstrating high levels of anti-HIV activity were used to identify and then purify two high molecular weight sialyated glycoproteins, salivary agglutinin (SAG) and mucin (MG2). Both of these purified glycoproteins inhibited HIV-1 infection in vitro at concentrations found in saliva. We subsequently demonstrated that the mechanism of inhibition involved binding of the salivary proteins to gp120, and subsequent shedding of gp120 from the virion. Prakobphol et al (2000), utilizing proteomic technology, demonstrated that SAG was identical to the lung scavenger receptor protein, gp-340, a member of the scavenger receptor cysteine rich (SRCR) family. We obtained a molecular clone for this gene, expressed the protein in mammalian cells and found that recombinant gp-340 was identical to SAG in terms of its structural and biologic activities. In the present proposal we will (1) Identify regions on gp120 that interact with gp-340; create stable transfected cells that express high levels of gp-340, and demonstrate that it is indeed identical to SAG in all of its biologic properties; (2) Identify discrete regions of gp-340 that mediate env binding and HIV inhibition; and (3) establish the mechanism(s) involved in the interaction of the bioactive portion of gp-340 in order to develop novel therapeutic agents with anti-HIV activity.