AIDS RESEARCH AND HUMAN RETROVIRUSES Volume 14, Number 5, 1998 Mary Ann Liebert, Inc. Sequence Note HIV Type 2 Vif Proteins Have Specific Conserved Amino Acid Motifs A.C. RIBEIRO,1 J. MONIZ PEREIRA,1 and I. BARAHONA1,2 Biological and clinical behaviors of HIV type 1 (HIV- 1) and HIV type 2 (HIV-2) vary significantly in terms of viral infectivity. Initially, HIV-2 was localized in west Africa, while HIV-1 rapidly spread to various countries in America, Europe, and Africa. Currently HIV-2 is also present in south central Africa, South America, North America, and Europe. Portugal is the European country with the highest percentage of HIV-2 infection, with 10% of AIDS cases due to HIV-2.1 Human immunodeficiency viruses contain the viral infectiv- ity factor, Vif, which is known to modulate HIV infection in cultures of T cell lines in a host cell-dependent manner. How- ever, the role and mechanisms of action of Vif remain largely unknown. HIV-1 strains defective in Vif generate virions that infect cell lines with an efficiency approximately 1000 times lower than wild-type viruses.2 More recent studies have shown that Vif is essential, in both types of HIV, for the infection of peripheral blood mononuclear cells (PBMCs) and also of some cell lines.3-6 During HIV-1 infection, Vif protein is found in the cyto- plasm both in a soluble form and associated with the mem- branes,7 and it is also present in the mature virus particle.8,9 HIV-1 Vif is encoded by a Rev-dependent singly spliced 5-kb transcript that is expressed late in the virus life cycle together with gag, pol, and env mRNAs.10 It is important during late events in the virus life cycle, especially at the stage of viral par- ticle formation, but its function is apparent only after the virus enters target cells.11-15 HIV-1 and HIV-2 have a similar but distinct genomic orga- nization and share only approximately 50% of nucleotide se- quence. The vif genes in HIV-1 and HIV-2 are both located be- tween the pol and env genes and encode proteins with similar molecular masses (23 kDa) and P/ values (10.35) but little global amino acid sequence similarity.16 The function and mechanism of action of viral proteins have been characterized mostly in HIV-1, and little is known about the mechanism of action occurring in HIV-2. A better under- standing of HIV-2 proteins might explain the differences be- tween these two types of viruses, in particular why HIV-1 is highly infective and HIV-2 is not. We have analyzed vif genes obtained from lymphocytes of several asymptomatic and symptomatic patients or from pri- mary isolates of HIV-2 strains in order to avoid adaptation of HIV-2 variants to the cell lines. We have also defined conserved and HIV-2-specific motifs present in Vif proteins from the amino acid sequences. Some of the nucleotide sequences of vif genes analyzed are from viruses of Guinea-Bissau patients: HIV-2Vm is from an asymptomatic patient, HIV-2ali is from a patient with AIDS- related complex (ARC) and HIV-2sar is from an AIDS patient. Other vif nucleotide sequences were obtained from Portuguese patients: HIV-2aug is from an asymptomatic patient, and HIV-2jaui and HIV-2JAu2 are from the same AIDS patient (but taken 3 months apart). Two of the strains—HIV-2ali and HIV-2jau—grow only in PBMCs but not in any T cell line, in- cluding the MT2 strain. Moreover, they are unable to induce syncytium formation and so they can be classified as non-syn- cytium-inducing (NSI) strains. vif genes from the different isolates were amplified by a sin- gle-round polymerase chain reaction (PCR), and the amplified products were subcloned in plasmid pSK+ (Stratagene, La Jolla, CA). Several clones of each strain were sequenced by the dideoxy method of Sänger. Representative clones of HIV-2ali, HIV-2jaui, and HIV-2JAu2 isolates have the GenBank acces- sion numbers L28934, L28935, and L28936, respectively. Al- ternatively, vif genes were cloned in plasmid pCR3 (Invitrogen, San Diego, CA) after nested PCR from PBMCs, and sequenced by the same method. In this study we present the sequence of 10 different vif genes from 5 different patients. Nucleotide sequence analysis shows that they are all similar, vif genes of HIV-2JAUi and HIV-2JAu2 are highly similar (97.2%), and correspond to different samples of the same patient. The lowest identity (83%) was obtained from the comparison of vif genes sequenced from HIV-2jAU and HIV-2VM- 'Departamento de Microbiología, Faculdade de Farmacia de Lisboa, 1600 Lisbon, Portugal. 2Instituto Superior Ciencias de Saúde-Sul, 2825 Monte da Caparica, Portugal. 465