A blood donor infected with human immunodeficiency virus-type 1 (HIV-1) and a cohort of six blood or blood product recipients infected from this donor remain free of HIV-1-related disease with stable and normal CD4 lymphocyte counts 10 to 14 years after infection. HIV-1 sequences from either virus isolates or patient peripheral blood mononuclear cells had similar deletions in the nef gene and in the region of overlap of nef and the U3 region of the long terminal repeat (LTR). Full-length sequencing of one isolate genome and amplification of selected HIV-1 genome regions from other cohort members revealed no other abnormalities of obvious functional significance. These data show that survival after HIV infection can be determined by the HIV genome and support the importance of nef or the U3 region of the LTR in determining the pathogenicity of HIV-1.

After prolonged infection with this attenuated strain of HIV-1, there is evidence of immunologic damage in three of the four subjects with detectable plasma HIV-1 RNA. The CD4 lymphocyte counts appear to be stable in the three subjects in whom plasma HIV-1 RNA remains undetectable.

Life-threatening opportunistic cytomegalovirus infection is a complication of the acquired immunodeficiency syndrome (AIDS) that occurs in 7.4% or more of patients with AIDS. Cytomegalovirus retinitis, colitis, esophagitis, and gastritis are the commonest manifestations of severe cytomegalovirus end-organ disease. Extensive trials with intravenous ganciclovir, a nucleoside analogue with myelosuppressive toxicity, have shown that ganciclovir halts the progression of cytomegalovirus retinitis and gastrointestinal disease. Since relapse is common when therapy is discontinued, most patients with AIDS need life-long maintenance therapy. The clinical response to ganciclovir therapy is usually accompanied by diminished shedding of the virus. Based on limited data, foscarnet, a pyrophosphate analogue, also appears to have some efficacy in treating cytomegalovirus infection. Unlike ganciclovir, foscarnet does not cause myelosuppression. An important direction for future clinical research is the development of more effective and less toxic therapy, as well as orally bioavailable drugs for maintenance therapy.

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Little is known about the functions of the matrix (M) protein of respiratory syncytial virus (RSV). By analogy with other negative-strand RNA viruses, the M protein should inhibit the viral polymerase prior to packaging and facilitate virion assembly. In this study, localization of the RSV M protein in infected cells and its association with the RSV nucleocapsid complex was investigated. RSV-infected cells were shown to contain characteristic cytoplasmic inclusions. Further analysis showed that these inclusions were localization sites of the M protein as well as the N, P, L and M2-1 proteins described previously. The M protein co-purified with viral ribonucleoproteins (RNPs) from RSVinfected cells. The transcriptase activity of purified RNPs was enhanced by treatment with antibodies to the M protein in a dose-dependent manner. These data suggest that the M protein is associated with RSV nucleocapsids and, like the matrix proteins of other negative-strand RNA viruses, can inhibit virus transcription.Human respiratory syncytial virus (RSV) is a non-segmented negative-strand RNA virus belonging to the family Paramyxoviridae, genus Pneumovirus (Collins et al., 1996). RSVinfected cells contain characteristic cytoplasmic inclusions. Previous studies have shown that these inclusions contain the nucleocapsid (N) protein, the viral polymerase (P and L proteins) (Collins et al., 1996) and the transcription elongation factor protein M2-1 (Garcia et al., 1993). It has been proposed that, as with Sendai virus, the P protein interacts with the newly synthesized N protein to prevent incorrect assembly of the nucleocapsid and to deliver it to the nascent RNA during genome replication (Curran et al., 1995 ;Garcia-Barreno et al., 1996), whereas the M2-1 protein is required for the synthesis of full-length viral RNA (Collins et al., 1996). These obser-

For the treatment of acyclovir-resistant herpes simplex infection in patients with AIDS, foscarnet has superior efficacy and less frequent serious toxicity than vidarabine. Once the treatment is stopped, however; there is a high frequency of relapse.

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Cytoplasmic inclusions in respiratory syncytial virus-infected cells comprising viral nucleocapsid proteins (L,N Respiratory syncytial virus (RSV), a member of the familyParamyxoviridae, is one of the most important viral agents causing lower respiratory tract disease in infants, the elderly, and immunocompromised patients of all ages (3, 6, 21). The genome of RSV is a nonsegmented negative-strand RNA encoding 11 proteins (3). In RSV-infected cells, the viral RNA with the L (polymerase), N (nucleocapsid), P (phosphoprotein), and M2-1 proteins form the polymerase complex in which the transcription of messenger and genomic RNA takes place. As the cytoplasmic inclusions in RSV-infected cells have been shown to contain all elements of the polymerase complex and are capable of transcription in isolation (1, 7), it is presumed that they are major sites of viral transcription.Several studies have shown that the N protein is the major driver for the formation of these cytoplasmic inclusions. N associates with viral RNA, and N-RNA complexes are resistant to RNase treatment (18). Inclusion-like structures are formed when the N and P proteins are coexpressed in cells (7), and this association results from a specific protein-protein interaction between N and P, which can be disrupted by mutagenesis (8, 24). Garcia et al. (7) also showed that the M2-1 protein is present in cytoplasmic inclusions; subsequent investigations confirmed that the association of the M2-1 protein with inclusions resulted from its association with P (16).We previously reported that the RSV M protein is also found in cytoplasmic inclusions late during infection, in association with the N, P, and M2-1 proteins (11). Since we have also shown that the M protein inhibits virus transcription (11), the role of the M protein in cytoplasmic inclusions may be to inhibit viral transcription as a prelude to viral assembly and budding, driven by the M protein bringing cytoplasmic nucleocapsids into association with RSV envelope proteins (10). The concept is supported by data indicating specific interactions between M and the cytoplasmic domains of envelope glycoproteins (10).To date, it is not known how M becomes associated with the nucleocapsid complex. In the current study, we demonstrate that the N terminus of M can bind directly to M2-1 in a cell-free assay and that M colocalizes with M2-1 in the cytoplasm of cells either infected with RSV or expressing only M and M2-1 proteins. Using a cotransfection system, it was demonstrated that M associates with inclusion-like structures formed by N and P only in the presence of M2-1. MATERIALS AND METHODS Cells and virus.Human epithelial (HEp2) cells were grown in Dulbecco's modified Eagle's medium supplemented with 10% fetal calf serum (FCS) at 37°C and 5% CO 2 . RSV subgroup A strain A2 (a gift from Paul Young, University of Queensland, Brisbane, Australia) was grown in HEp2 cells as previously described (9). To prepare the virus stock, an 80% confluent cell monolayer was infected with RSV at a multiplicity of infect...