Cross-Neutralizing Antibodies in Rabbits Immunized with HIV-1 gp160 Purified from Simian Cells Infected with a Recombinant Vaccinia Virus

Abstract

A recombinant vaccinia virus in which the transcription of the human immunodeficiency virus type 1 (BRU isolate) env gene is driven by the 11K late vaccinia promoter yields about 10-fold higher amounts of gp160 env protein upon infection of monkey cells than does a recombinant in which gp160 is expressed using the 7.5K early-late promoter. The gp160 was purified from detergent lysates of infected cells by lentil lectin affinity chromatography followed by immunoaffinity chromatography, and was obtained in yields of 1-2 mg/10(9) cells of material estimated to be about 70% pure. Pairs of rabbits were immunized with purified gp160 using either one of five different adjuvants or an immunostimulating complex. In all cases a substantial humoral immune response was obtained after boosting, including an activity that neutralized the homologous (BRU) isolate of HIV-1. In some cases, this activity also neutralized two distantly related isolates, SF2 and MN.

Improved Elicitation of Neutralizing Antibodies against Primary Human Immunodeficiency Viruses by Soluble Stabilized Envelope Glycoprotein Trimers

“…Previous studies have demonstrated that gp120 induces neutralizing antibodies active against clinical HIV-1 isolates only after multiple immunizations, and then only at very low titers and with limited breadth (3,4,6,14,28,29,41,57,76,79). Nonetheless, since no other defined immunogen has proven consistently superior to gp120 in this respect, the use of gp120 as a point of comparison was reasonable (6,33,41,75). In this study, we utilized a conservative immunization protocol consisting of a priming inoculation followed by two boosts.…”

“…Most antibodies elicited against the HIV-1 envelope glycoproteins during natural infection or after vaccination are incapable of neutralizing HIV-1 infectivity in vitro (3,4,14,29,33,41,42,54,57,75,76,79). Neutralizing antibodies that are elicited often are restricted to a limited number of HIV-1 strains.…”

“…When the gp120-gp41 junction is modified to reduce proteolytic cleavage, these soluble gp140 glycoproteins assemble into dimers and tetramers in addition to the monomeric forms (9,21,22). The elicitation of neutralizing antibodies by oligomeric forms of soluble gp140 has been disappointing, perhaps because these oligomers do not fully resemble the biologically relevant envelope glycoprotein trimers (6,21,33,75).…”

Characterization of the Outer Domain of the gp120 Glycoprotein from Human Immunodeficiency Virus Type 1

“…Many monoclonal antibodies (MAbs) to the HIV-1 envelope glycoproteins have been derived from naturally infected humans, as well as from animals immunized with viral envelope glycoproteins (3,5,15,17,27,29,39,51,54,64,65,71). Generally, they can be divided into four categories (43).…”

Elicitation of Neutralizing Antibodies with DNA Vaccines Expressing Soluble Stabilized Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Trimers Conjugated to C3d

“…Oligomeric or trimeric forms of Env that more closely mimic the native protein structure on the viral membrane elicit low to moderate levels of neutralizing antibodies (3,17,21,35,44,58). The reason for these disappointing results may be due in part to the inability of these immunogens to remain as a trimer upon inoculation.…”