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.

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Accurate assessment of gestational age, date of parturition, and evaluation of placental abnormalities are essential to monitor obstetrical and fetal complications in captive chimpanzee (Pan troglodytes) breeding colonies. Since ultrasonography is a safe and noninvasive technique for monitoring chimpanzee pregnancies, we have developed a technique to estimate the date of parturition using the fetal biparietal diameter (BPD) of the skull from real-time ultrasonographic measurements. A formula for determining gestational age was based on analysis of data obtained from 62 pregnancies over an %year period. From this formula an estimated gestational age was calculated and compared with menstrual cycle data from the period near the time of the estimated date of conception (EDC). If the data from the scan and cycle history were in agreement within 7 days, the estimate date of conception was corrected to be 3 days prior to detumescence of the sex cycle phase. Lastly, the estimated date of parturition (EDP) was predicted to be 240 days after the EDC. To evaluate the utility of this prediction, we subsequently examined 13 chimpanzee pregnancies using the above technique and compared it to the actual date of parturition (ADP). Nine of the 13 chimpanzees delivered within 2 weeks of the EDP. In addition to estimating gestational age, ultrasonography may be a useful tool for evaluating fetal growth and placental abnormalities and assessing third trimester complications in chimpanzee pregnancies.