87 ANTI-RETROVIRAL ACTIVITIES OF BAICAL[N IN VITRO AND iN VIV0, llongshan Chert, Xing-quan Zhang, Li Teng, Xiao-xian Wu, Yao-zeng Lu, Xiao-shan Tang, Xian-shu Yang, xu- guang Yen, Institute of Medicinal Biotechnology, institute of Experimental, Chinese Academy of Medical Sciences, Beijing, I00050, China. Baicalin
is a f l a v o n o i d i s o l a t e d from Chinese t r a d i t i o n a l
baicalensis. It competatively inhibited HIV-I recombinant P66 r e v e r s e transcriptase with IC50 of 22u~ in vitro, inhibited H!V-I CPE, [FA and P24 in H9 c e l l c u l t u r e s with IC50 of i. 6, 3. 3 and 4. 74 ug/ml, tixe s e l e c t i v e indexes were 81.~I, ]9.68 a ~ 27 55 r e s p e c t i v e l y . ~ u r i n e leukemia v i r u s ip i n f e c t e d B~IL/C mice resulted sigaificant spleenomegaly, i e u k o c y t o s i s and s l i g h t anemia. B a i c a l i n ~ g/kg per oral were given to 6 NULVrav infected mice, treatment was started 2 hrs. a f t e r i n f e c t i o n b i d for 20 dass s i g n i f i c a L t l 5 inhibited the
spleen index, white blood count and increased red blood count and ~emoglobulin ~. SIVmac strain iv infected R~esus monkey developed viramia and iymphopathy effect. 3aicalin I00 and 300 mg/kg, 2 monkeys in each dose group, were given by oral QD, 2 times before SIV infection and continously QD up to 60 days after infection. ~ood samples were taken before; i0, 14, 17, 21, 30 days during and 2 and 30 days a f t e r t r e a t m e n t for SlY c u l t i v a t i o ~ and PCR d e t e c t i o n , The e x p e r i m e n t a l monkeys were s a c r i f i z e d 30 days a f t e r c e s s a t i o n of t r e a t m e n t , the iympho-nodes were taken for p a t h o l o g i c a l study, The r e s u l t s showed t h a t SIV were found in BCL t r e a t e d monkey sera, bu~ the p a t h o l o g i c a l f i n d i n g s of the SIV i n f e c t e d monkey's lymph- nodes in t r e a t e d group were l e s s than t h a t of the c o n t r o l group.
88 Sequences within the HIV- 1 LTR Required for Strand Transfer By Integrase In Vitro D. J. Hazuda, P. J. Felock, R.L. LaFemina, and A.L.Wolfe Dept. of Antiviral Research, Merck Research Labs, West Point, Pa, 19486 Integration of the human immunodeficiency virus (HIV- 1) provirus into the genome of the host cell is required for productive infection of cultured T-lymphoid cells. The endonucleolytic and strand transfer processes which are necessary for integration are mediated by a unique viral enzyme, integrase, presenting potential opportunities for the development of selective HIV therapeutics. It is therefore essential to evolve a detailed understanding of the functional interactions between this enzyme and its specific viral DNA substrate. We have used a plate based assay (Hazuda et al., 1994, NAR 22, pp. 1121-1122 ) which uncouples the requirement for donor and target substrates to analyze donor substrate sequences for their potential influence on the HIV-1 integrase-mediated strand transfer reaction. Using different retroviral LTR's as donor substrates, the MuLv LTR was shown to be inactive, and the HTLV LTR partially active relative to the analogous HIV sequence. Careful mutational analysis of the terminal 6 bases within the LTR known to be important for cleavage and strand transfer confirmed previous studies, but also demonstrated that sequence differences between the three LTR's within this region are insufficient to account for their disparate activities. To address this discrepancy, a series of chimeric LTR's were constructed switching defined sequences between HIV and MuLv. The results of these studies suggest that HIV integrase requires two additional upstream sequences within the LTR for efficient donor activity. In HIV, substituting either of these regions with sequences from the MuLv LTR reduced activity. In contrast, the activity of the MuLv LTR was enhanced when the HIV motifs were introduced. In either case, substituting the intervening sequences had no measurable effect. Further characterization of the contribution made by specific base pairs within the two regions identified by these chimera analyses is currently underway.