SCIENTIFIC CORRESPONDENCE

tion may not be at the expense of losing HIV-1 subtype and second-receptor use the ability to use CCR5. Alternatively, it is possible that most SI isolates contain a SIR - The identification of the chemo­ is also a more divergent set of viruses mixed population of SI and NSI quasi­ kine receptors fusin (now renamed known as the outlier (0) group. It is pos­ species, and thus seem to be able to use CXCR4) and CCR5 as the main co­ sible that different genetic subtypes might both CCR5 and CXCR4. receptors for HIV-1 entry into CD4 + cells preferentially use different co-receptors, To confirm our observations on HOS of the immune system will assist our hence contributing to the uneven world­ cells, we tested the ability of isolates from understanding of HIV-1 transmission and wide distribution of viral subtypes. The different subtypes to replicate in peripher­ pathogenesisH. Here we report data only recent report on this topic indicates al blood mononucleocytes (PBMC) from showing that the phenotype of the virus, that virus strains from subtypes A, C and individuals homozygous or heterozygous rather than its genetic subtype, deter­ E can use CCR5, although only a few for a recently identified defective allele of mines receptor usage. viruses were tested5. CCR5 that contains a 32-nucleotide dele­ The phenotype of a virus is closely We therefore examined 18 viral isolates tion (L'.32) in the second external loop and associated with whether it preferentially from the HIV-1 M group (at least three encodes a non-functional protein for HIV- uses CXCR4 or CCR5: NSI viruses, for each of subtypes A, B, C, D and E), 1 entry7·H. We reasoned that if isolates which are macrophage-tropic and do not and two from the 0 group, for second- from non-B subtypes could use cofactors other than CCR5 for entry into PBMC, SECOND-RECEPTOR USAGE BY DIFFERENT GENETIC SUBTYPES OF HIV-1 they would replicate in the cells of L'.32 homozygotes. We therefore tested the p24 production in HOS.CD4 cells* p24 production in PBMC same panel of viruses for replication in

Virus Subtype Phenotype CCR1-4 1 CCR5 CXCR4 PB' wtjwt wt/!>32 !>32/!>32§ stimulated PBMC from two homozygous (L'.32/L'.32), one heterozygous (wt/L'.32) and 93KE101 A NSI + + + one wild-type (wt/wt) individuals (see 931N103 A NSI + + + table). No NSI isolate, irrespective of the 92RW009 A Sl + + + + + 92HA593 B Sl + + + + + genetic subtype, could replicate in PBMC 92HA594 B Sl + + + + + from L'.32 homozygotes, but all replicated 92HA596 B Sl + + + + + efficiently in wild-type and heterozygote JRCSF B NSI + + + PBMC. In contrast, every SI isolate could JRFL B NSI + + + replicate in all PBMC regardless of CCR5 NL43 B Sl + + + + genotype, presumably by using CXCR4. 92ZW101 c NSI + + + Thus, there is an absolute requirement for 92ZW102 c NSI + + + the presence of a functional CCR5 allele 92ZW106 c Sl + + + + for replication of NSI strains of all the 94KE102 D NSI + + + genetic subtypes tested. 94KE103 D NSI + + + We conclude that CCR5 and CXCR4 92UG046 D Sl + + + + + 93TH304 E Sl + + + + + are the main co-receptors for HIV-1 sub­ 93TH305 E NSI + + + types A-E and group 0. Viral phenotype 93TH307 E NSI + + + is dominant over genotype in terms of CA9 0 NSI + + + co-receptor usage. Thus, the uneven MVP5180 0 Sl + + + + + worldwide distribution of HIV-1 subtypes

*Plus symbol, p24 concentration >60 pg ml- 1 ; minus symbol, ~10 pg ml- 1 is more likely to be the result of stochastic 1 Identical results were obtained with CCR1, 2, 3 and 4. dissemination. However, it is conceivable 'Negative control cells containing vector pBABE-puro only2 that sequence polymorphisms in CCR5 § Identical results were obtained with PBMC from two cases. and CXCR4 in different human popula­ tions could affect the efficiency of HIV-1 induce syncytia, use CCR5, whereas SI receptor usage. These 20 HIV-1 isolates, entry in a subtype-dependent manner. strains, which induce syncytia or are originating from 8 different countries, had Finally, the common usage of CCR5 and adapted to T-cell lines, prefer CXCR4. previously been genetically subtyped and CXCR4 by multiple genetic subtypes sug­ There is one example of a broadly tropic their NSI or SI phenotypes determined in gests that drugs targeting these receptors HIV-1 strain able to use both CCR5 and MT-2 cells. To assess second-receptor use, might not be unduly compromised by 4 CXCR4 for entry • In addition, CCR1, we added 500 TCID50 (half-maximal HIV-1 genetic diversity. CCR2b and CCR3 can function to a tissue-culture infectious dose) of each iso­ Linqi Zhang limited extent as HIV-1 co-receptors for late to HOS cells engineered to express Yaoxing Huang some viral strains3- 5• With a single excep­ human CD4 and CCR1, CCR2b, CCR3, Tian He tion', these studies used HIV-1 strains or CCR4, CCR5 or CXCR4 (ref. 2). We Yunzhen Cao env genes derived solely from genetic assessed virus replication using super­ David D. Ho* subtype B, the subtype of HIV-1 that pre­ natant p24 antigen concentration on day 6 Aaron Diamond AIDS Research Center, dominates in North America and Europe after infection. The Rockefeller University, but not globally. Nine HIV-1 genetic sub­ We found that each NSI isolate could New York, types (A to I) have now been designated utilize CCR5 for entry, irrespective of its New York 10016, USA within the major (M) group, and there genetic subtype (see table). However, SI e-mail: [email protected]

isolates could use both CCR5 and *To whom correspondence should be addressed. CXCR4, except for one subtype B TCLA Scientific Correspondence 1. Feng, Y., Broder, C. C., Kennedy, P. E. & Berger. E. A. virus (NL43) and one subtype C SI prima­ Science 272, 872-877 (1996). Scientific Correspondence is intended to ry isolate (92ZW106), which could only 2. Deng, H. eta/. Nature 381. 661-666 (1996). provide a forum in which readers may utilize CXCR4. The finding that dual­ 3. Dragic, T. eta/. Nature 381, 667-673 (1996). raise points of a scientific character. 4. Doranz, B. J. eta/. Ce//85, 1149-1158 (1996). receptor usage is more common among SI 5. Choe, H. et al. Ce//85, 1135-1148 (1996). Priority will be given to letters of fewer 6. Alkhatib G. eta/. Science 272, 1955-1958 (1996). than 500 words and ten references. strains suggests that adaptation of HIV-1 7. Liu, R. eta/. Ce/186, 367-377 (1996). to use CXCR4 during phenotypic evolu- 8. Samson, M. eta/. Nature 382, 722-725 (1996). 768 NATURE · VOL 383 · 31 OCTOBER 1996