11th International AIDS Conference Vancouver, British Columbia — July 7-12, 1996

Int Conf AIDS 1996 Jul 7-12; 11:5 (abstract no. We.A.142)
Thompson J, Hu SL, Kuller L, Travis B, Morton WR, Agy MB; University of Washington, Seattle, WA, USA.

OBJECTIVE: To determine the macaque infectious dose (MID) of SHIVIIIB in pig-tailed macaques, Macaca nemestrina, in preparation for challenging animals previously immunized with an envelope based candidate HIV-1 vaccines.

METHODS: SHIVIIIB used in this study was prepared and characterized by Virus Research Institute and obtained from TSI Mason Laboratories. Following initial studies that demonstrated SHIVIIIB replication in M. nemestrina PBMC in vitro, a two-phase animal titration study was undertaken. In the first phase, three pairs of animals were inoculated intravenously with SHIVIIIB doses of 100, 10, or 1 TCID50. In the second phase, one macaque was inoculated with 10 TCID50, two with 1 TCID50 and three with 0.1 TCID50. The animals were monitored by virus culture, quantitative PBMC DNA PCR and serology.

RESULTS: All of the macaques except one 1 TCID50 recipient in phase one and one 0.1 TCID50 recipient in phase two became infected. Seroconversion occurred within four weeks in all virus-positive macaques. Virus culture results were confirmed by quantitative DNA PCR; both techniques revealed relatively heavy virus loads in PBMC from all infected animals regardless of their respective inoculating doses.

CONCLUSION: Our results define the MID50 for SHIVIIIB in M. nemestrina to be in the range of 0.1-1.0 TCID50. Due to the high levels of virus recovered and the length of time that our study animals remained viremic, we concluded that SIV-HIV chimeras may play a significant role during HIV-1 candidate vaccine evaluation in models utilizing pig-tailed macaques.

960707
WeA142

Copyright © 1996 - International AIDS Society (IAS). Reproduction of this abstract (other than one copy for personal reference) must be cleared through the IAS.