Titration of a Vaccine Stock Preparation of Human Immunodeficiency Virus Type 1_sf2in Cultured Lymphocytes and in Chimpanzees

Abstract

A large stock preparation of the HIV-1SF2 isolate has been derived after serial passage in human peripheral blood mononuclear cells (PBMCs). This viral stock has a titer of 10(4.9) TCID50 in human PBMCs and 10(4.2) TCID50 in chimpanzee PBMCs. By inoculation into animals the 50% chimpanzee infectious dose titer was found to be about 10(2.3). Virus isolation from animals was achieved on most occasions within 1-4 weeks after inoculation and then became transient. Viral RNA and DNA PCR analyses confirmed the virus infection of the chimpanzees. Anti-HIV antibody levels in the inoculated animals ranged from 1:400 to 1:6400 as measured by ELISA. About 680 vials of this stock preparation, frozen at -190 degrees C, are available for future studies of vaccines and antiviral therapies.

Lactobacilli-Expressed Single-Chain Variable Fragment (scFv) Specific for Intercellular Adhesion Molecule 1 (ICAM-1) Blocks Cell-Associated HIV-1 Transmission across a Cervical Epithelial Monolayer

“…Supernatants were cleared of cells by centrifugation and filtered through a 0.2-m syringe filter (Millipore). The cell-free virus was quantified by HIV-1 p24 ELISA (sensitivity of 12.5-350 pg/ml; PerkinElmer) and by coculture with PBMC from a healthy, HIV-negative donor to determine TCID 50 as previously described (15).…”

Transmission of Simian Immunodeficiency Virus SIVcpz and the Evolution of Infection in the Presence and Absence of Concurrent Human Immunodeficiency Virus Type 1 Infection in Chimpanzees

“…The study design included one naive control animal, which would be used to receive SIVcpz by the same dose and route if one of the routes of transmission failed in any of the HIV-1-infected animals. Furthermore, since the infectious dose has been demonstrated not to influence the levels of viremia and kinetics of SIV infection (17) or HIV-1 infection (23), an estimated minimum of a log-fold excess infectious dose was used based on titration studies in macaques and chimpanzees (5,23,25). Whenever possible, blood samples from all animals in the study were drawn 1 to 2 months prior to exposure and at 2-week intervals for the first 2 months and then monthly until 6 months postexposure, when sampling was reduced to once every 2 months for the 1-year follow-up period.…”

Characteristics of primary infection of a European human immunodeficiency virus type 1 clade B isolate in chimpanzees.

“…The chimpanzee-human immunodeficiency virus type 1 (HIV-1) model has been used successfully to demonstrate the efficacy of several experimental HIV-1 vaccines in protection from infection (Arthur et al, 1989 ;Berman et al, 1988 ;Bruck et al, 1994 ;Girard et al, 1991) with common laboratory strains of HIV-1 such as Lai\IIIB (Arthur et al, 1989) and SF2 (Murthy et al, 1996). There is substantial concern that the characteristics of these laboratory strains are not representative of primary Author for correspondence : Jonathan Heeney.…”

“…HIV-1 SF# stock grown in human peripheral blood mononuclear cells (PBMC) to avoid problems with human cell lines induced a relatively weak infection in chimpanzees with only transient and inconsistent PCR and virus isolation, and subsequently a relatively poor immune response (Girard et al, 1995 ;Murthy et al, 1996). In an effort to provide a more clinically relevant virus stock for HIV-1 vaccine efficacy trails in chimpanzees, an initiative was launched by Programme EVA (European Vaccine against AIDS) sponsored by the EC Biomedicine and Health programme, and undertaken together with the European Centralised Facility for preclinical HIV-1 vaccine development (ECCF), to evaluate and select European clade B HIV-1 primary isolates as candidate challenge viruses.…”

“…Infection of chimpanzees with an HIV-1 SF# stock was described by Murthy et al (1996). Of the (non-Lai\IIIB) challenge virus stocks described so far for chimpanzees, only HIV-1 SF# is highly similar to the North American clade B consensus sequence (Myers et al, 1994).…”