NEONATAL DISEASE INDUCED BY SIV INFECTION OF THE RHESUS-MONKEY (MACACA-MULATTA)

Seven 72-hr-old Indian origin rhesus monkeys (Macaca malatta) were ino culated with 10 animal ID50 of SIV/Delta(B670). Nine age-matched anima ls were used as uninoculated controls. All seven inoculated animals be came infected as verified by viral isolation and SIV p26 antigenemia. Five of seven infected animals died within a mean of 31 days (range, 2 6-41 days), with high levels of antigenemia beginning 1-2 weeks postin oculation (PI) that persisted until death. Absolute lymphocyte numbers were within normal limits in all animals in both groups throughout th e study. Inoculated animals that died within a mean of 31 days (short- term survivors) had significantly lower numbers of CD4(+)CD29(+) (help er/inducer) lymphocytes than did long-term surviving inoculated animal s through 3 weeks PI. Numbers of CD4(+) lymphocytes were no different when controls were compared to all inoculated animals through 4-5 week s PI. The two inoculated animals surviving 216 and 423 days PI (long-t erm survivors) did demonstrate declining CD4(+) cells, but only late i n disease. CD8(+) lymphocytes were significantly lower in short-term s urvivors when compared to long-term survivors through 5 weeks PI. Anti body production against SIV viral proteins was detected only in the lo ng-term survivors and was similar to results from past studies in juve niles. Clinical signs in the inoculated group were consistent with tho se seen in past studies on older animals. Persistent bacterial infecti ons, primarily of the GI and respiratory tracts, were seen in the infe cted group. Aside from the lack of some opportunistic infections such as cytomegalovirus (CMV) and Pneumocystis carinii, necropsy findings w ere not different when compared to past studies on juvenile animals. W e concluded from the experimental results that mean survival time afte r inoculation in 3-day-old infants is considerably shorter than in ani mals inoculated as juveniles and that a greater percentage of infected animals demonstrated persistent antigenemia and progressive disease. A decline in the CD4(+)CD29(+) lymphocyte subset may be a more reliabl e early indicator of progressive disease and early death than declinin g CD4(+) percentages in the SIV-infected neonate.