Sensitization of rhabdo-, lenti-, and spumaviruses to human serum by galactosyl(alpha1-3)galactosylation

Vesicular stomatitis virus, human immunodeficiency virus type 2, and human foamy virus, which were produced by cell lines expressing galactosyl(alpha1-3)galactosyl (alphaGal) sugars, were found to be less stable in human serum than those from alphaGal-negative cells, indicating that galactosyl(alpha1-3)galactosylation sensitizes these viruses as well as mammalian type C oncoviruses (Rother et al., J. Exp. Med. 182:1345-1355, 1995; Takeuchi et al., Nature (London) 379:85-88, 1996) to complement killing via natural anti-alphaGal antibodies. Thus, virus killing mediated by anti-alphaGal antibodies may play a role as a barrier to animal-to-human infection of various enveloped viruses. Virus vectors for human in vivo gene therapy based on the viruses mentioned above should be produced from alphaGal-negative cells.

Biological characterization of human immunodeficiency virus type 1 clones derived from different organs of an AIDS patient by long-range PCR

In order to characterize the biological properties of human immunodeficiency virus type 1 (HIV-1) variants from different tissues (peripheral blood mononuclear cells [PBMC], lymph node, spleen, brain, and lung) of one patient, we have chosen long-range PCR to amplify virtually full-length HIV proviruses and to construct replication-competent viruses by adding a patient-specific 5' long terminal repeat. To avoid selection during propagation in CD4+ target cells, we transfected 293 cells and used the supernatants from these cells as challenge viruses for tropism studies after titration on human PBMC. Despite differences in the V3 loop of the major variants found in brain and lung compared to lymphoid tissues all recombinant HIV clones obtained showed identical cell tropism and replicative kinetics. After infection of human PBMC these viruses replicated with similar kinetics, with a slow/low-titer, non-syncytium-inducing phenotype. In contrast to the prediction of macrophage tropism, drawn from the V3 loop sequence, none of these viruses infected monocyte-derived macrophages. The challenge of blood dendritic cells by these recombinant viruses in the presence of tumor necrosis factor alpha, granulocyte-macrophage colony-stimulating factor, and interleukin-4 resulted in a productive infection only after adding stimulated CD4+ T lymphocytes. Therefore, the biological properties of the HIV-1 variants derived from nonlymphoid tissue of this patient did not differ from those of HIV-1 variants from lymphoid tissue with respect to tropism for primary cells such as PBMC, macrophages, and blood dendritic cells.

Multiple extracellular domains of CCR-5 contribute to human immunodeficiency virus type 1 entry and fusion

Human immunodeficiency virus type 1 (HIV-1) entry is governed by the interaction of the viral envelope glycoprotein (Env) with its receptor. The HIV-1 receptor is composed of two molecules, the CD4 binding receptor and a coreceptor. The seven-membrane-spanning chemokine receptor CCR-5 is one of the coreceptors used by primary isolates of HIV-1. We demonstrate that the mouse homolog of CCR-5 (mCCR-5) does not function as an HIV-1 coreceptor. A set of chimeras of human CCR-5 and mCCR-5 was studied for Env-induced cell fusion and HIV-1 infection. Using the HIV-1ADA envelope glycoprotein in a syncytium formation assay, we show that replacement of any fragment containing extracellular domains of mCCR-5 by its human counterparts is sufficient to allow Env-induced fusion. Conversely, replacement of any fragment containing human extracellular domains by its murine counterpart did not lead to coreceptor function loss. These results show that several domains of CCR-5 participate in coreceptor function. In addition, using a panel of primary nonsyncytium-inducing and syncytium-inducing isolates that use CCR-5 or both CXCR-4 and CCR-5 as coreceptors, we show that the latter dual-tropic isolates are less tolerant to changes in CCR-5 than strains with a more restricted coreceptor use. Thus, different strains are likely to have different ways of interacting with the CCR-5 coreceptor.

The cyclin encoded by Kaposi's sarcoma-associated herpesvirus stimulates cdk6 to phosphorylate the retinoblastoma protein and histone H1

Kaposi's sarcoma-associated herpesvirus (KSHV or human herpesvirus 8) is a novel gammaherpesvirus implicated in the cause of Kaposi's sarcoma and certain malignancies of lymphatic origin. One of the candidate genes possibly involved in promoting tumor development is an open reading frame (ORF) with sequence similarity to human type D cyclin genes. This cyclin-like gene, when expressed in tissue culture cells, promotes phosphorylation and inactivation of the retinoblastoma tumor suppressor protein and thereby may result in deregulation of cell division control. We report here the biochemical characterization of this cyclin (KSHV-cyc) and the kinase activity that it elicits upon expression in tissue culture cells. We demonstrate that the kinase activity associated with KSHV-cyc is sensitive to the cdk inhibitor p27 (KIP) and due to activation of cdk6. However, in contrast to cdk6 activated by cellular type D cyclins, the cdk6 activated by KSHV-cyc is capable of phosphorylating not only the retinoblastoma protein but also histone H1. This finding implies that activation by KSHV-cyc alters the substrate preference of this cdk. This may have important physiological consequences in that the kinase activity triggered by this viral cyclin may abrogate cell cycle checkpoints in addition to those targeted by cellular cyclin D-cdk6 kinase.

CD4-independent infection by human immunodeficiency virus type 2 strain ROD/B: the role of the N-terminal domain of CXCR-4 in fusion and entry

The human immunodeficiency virus type 2 (HIV-2) strain ROD/B can efficiently use the 7tm chemokine receptor CXCR-4 as a primary receptor to enter CD4-negative cells. We have stably expressed CXCR-4 on mink lung Mv-1-lu and feline kidney CCC cells (normally restrictive to HIV entry) and have shown efficient fusion, entry, and replication of ROD/B. Mutation of the two N-linked glycosylation sites on CXCR-4 (N11-->I, and N176-->Q) or pretreatment of CCC or Mv-1-lu cells expressing wild-type CXCR-4 with the glycosylation inhibitor tunicamycin increased fusion and entry by ROD/B. Deletion of portions of the N terminus of CXCR-4 resulted in a 3- to 10-fold decrease in cell-free infection by ROD/B and complete inhibition of cell-cell fusion by both ROD/B and another HIV-2 strain, CBL23. These data suggest that the N-terminal domain of CXCR-4 is involved in but is not essential for the efficient fusion of ROD/B with CD4-negative cells. Deletion of the C-terminal (intracellular) domain of CXCR-4 did not significantly affect entry by ROD/B, indicating that intracellular signalling through this domain does not play a significant role in entry by HIV-2.

Pediatric Vesicoureteral Reflux Guidelines Panel summary report on the management of primary vesicoureteral reflux in children

PURPOSE

The American Urological Association convened the Pediatric Vesicoureteral Reflux Guidelines Panel to analyze the literature regarding available methods for treating vesicoureteral reflux diagnosed following a urinary tract infection in children and to make practice policy recommendations based on the treatment outcomes data insofar as the data permit.

MATERIALS AND METHODS

The panel searched the MEDLINE data base for all articles from 1965 to 1994 on vesicoureteral reflux and systematically analyzed outcomes data for 7 treatment alternatives: 1) intermittent antibiotic therapy, 2) bladder training, 3) continuous antibiotic prophylaxis, 4) antibiotic prophylaxis and bladder training, 5) antibiotic prophylaxis, anticholinergics and bladder training, 6) open surgical repair and 7) endoscopic repair. Key outcomes identified were probability of reflux resolution, likelihood of developing pyelonephritis and scarring, and possibility of complications of medical and surgical treatment.

RESULTS

Available outcomes data on the various treatment alternatives were summarized in tabular form and graphically, and the relative probabilities of possible outcomes were compared for each alternative. Treatment recommendations were based on scientific evidence and expert opinion. The panel concluded that only a few recommendations can be derived purely from scientific evidence of a beneficial effect on health outcomes.

CONCLUSIONS

For most children the panel recommended continuous antibiotic prophylaxis as initial treatment. Surgery was recommended for children with persistent reflux and other indications, as specified in the document.

Etiology of AIDS-related Kaposi's sarcoma and lymphoma

Kaposi's sarcoma (KS) and non-Hodgkin's lymphomas (NHL) are common consequences of HIV infection. These tumours appear to be precipitated by herpesviruses. Epstein-Barr virus (EBV) is implicated as a cause of up to 50% of systemic NHLs and up to 100% of central nervous system lymphomas in patients with AIDS. KS may be a consequence of the newly identified gamma-herpesvirus KSHV (KS-associated herpesvirus or HHV-8). This herpesvirus is found in all KS biopsies from different epidemiologic forms of this disease. KSHV is also implicated in the pathogenesis of a rare form of B cell lymphoma called body-cavity based lymphoma or primary effusion lymphoma (PEL).

CD4-independent infection by HIV-2 (ROD/B): use of the 7-transmembrane receptors CXCR-4, CCR-3, and V28 for entry

We have assayed a variety of 7tm chemokine receptors (CCR-2b, CCR-3, CCR-4, CCR-5, CXCR-1, CXCR-4) and two orphan 7tm receptors (V28 and EBI.1) for their ability to allow infection of CD4-negative feline kidney CCC cells by the HIV-2 strains ROD/A and ROD/B. We found that ROD/B was able to use CXCR-4 transiently expressed in CCC cells, and infection by ROD/A was enhanced 15-fold in the presence of sCD4. Feline CCC cells also became permissive to ROD/B and ROD/A entry when transiently transfected with the chemokine receptor CCR-3 or the orphan 7tm receptor V2B, when cultured in the presence of sCD4. Entry of ROD/A into CCC cells expressing CCR-3 could be blocked by 800 ng/ml eotaxin, the natural ligand for CCR-3.

Role of the amino-terminal extracellular domain of CXCR-4 in human immunodeficiency virus type 1 entry

We have studied the role of the N-terminal extracellular domain of the human immunodeficiency virus type 1 (HIV-1) coreceptor, CXCR-4, in the entry and fusion of syncytium-inducing strains of HIV-1. Progressive deletions were introduced in the N-terminal extracellular domain of CXCR-4 and the effect on infection by different isolates was tested. Infection of cells expressing the different CXCR-4 deletion mutants by HIV-1 LAI and 89.6 was reduced only about twofold. In contrast, the HIV-1 GUN-1 and RF isolates were substantially more impaired in their ability to mediate cell-free infection and cell-cell fusion. Since LAI and RF are T-cell line-tropic viruses while 89.6 and GUN-1 are dual tropic, no clear correlation between tropism and requirements for CXCR-4 N-terminal sequences emerged. We also introduced point mutations at the two N-linked glycosylation sites. The isolates tested (LAI, RF, GUN-1, and 89.6) were not affected by the removal of predicted N-linked glycosylation sites in CXCR-4. We conclude that distinct virus strains interact differently with the CXCR-4 coreceptor and that the N-terminal extracellular domain is not the sole functional domain important for HIV-1 entry.

A novel exogenous retrovirus sequence identified in humans

A 932-bp retrovirus sequence was cloned by reverse transcriptase PCR from salivary gland tissue of a patient with Sjögren's syndrome. The sequence is related to that of type B and type D retroviruses and was present in a sucrose density gradient fraction corresponding to that of an enveloped retrovirus particle. Sequences amplified from tissues of eight individuals with or without Sjögren's syndrome had over 90% similarity and were present at a level of less than one copy per 10(3) cells. The sequence was not detectable in human genomic DNA by PCR or by Southern hybridization. These data indicate that the sequence represents an infectiously acquired genome, provisionally called human retrovirus 5.

Infection of human cells by an endogenous retrovirus of pigs

The possible use of pig organs and tissues as xenografts in humans is actively being considered in biomedical research. We therefore examined whether pig endogenous retrovirus (PERV) genomes can be infectiously transmitted to human cells in culture. Two pig kidney cell lines spontaneously produce C-type retrovirus particles. Cell-free retrovirus produced by the PK-15 kidney cell line (PERV-PK) infected pig, mink and human kidney 293 cell lines and co-cultivation of X-irradiated PK-15 cells with human cells resulted in a broader range of human cell infection, including human diploid fibroblasts and B- and T-cell lines. Kidney, heart and spleen tissue obtained from domestic pigs contained multiple copies of integrated PERV genomes and expressed viral RNA. Upon passage in human cells PERV-PK could rescue a Moloney retroviral vector and acquired resistance to lysis by human complement.

Our retroviral heritage

Darwin could not have foretold that we are descended from viruses as well as from apes. While there is clear evidence that viral diseases, such as polio and rabies, affected ancient civilizations, viruses were not defined until the early years of this century, shortly after the rediscovery of mendelian genetics. That retroviral genomes can oscillate between infectious and genetic modes of transmission seemed preposterous before the discovery of reverse transcription in 1970. Those of us who had earlier provided mendelian evidence for germ-line transmission of retroviruses were subject of friendly ridicule. Today, the shunting of genetic elements between chromosomes and RNA, and the generation of processed pseudogenes, seems commonplace. It is timely, however, to revisit the topic of human endogenous retroviruses-the subject of this article.

Detection of human herpesvirus 8 DNA in semen from HIV-infected individuals but not healthy semen donors

OBJECTIVE

To ascertain the prevalence of Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus (HHV) type 8, and cytomegalovirus (CMV) DNA in semen was investigated.

METHODS

Amplification by nested polymerase chain reaction was used to detect viral DNA sequences in samples from 24 HIV-infected gay men, 15 of them with Kaposi's sarcoma (KS), and 115 healthy donors.

RESULTS

Six of the 24 HIV-infected patients had detectable HHV-8 DNA in their semen: three of the 15 patients with KS and three of the nine patients without KS. CMV DNA was detected in 20 semen samples from HIV-infected patients. None of the semen samples from healthy donors had detectable HHV-8 DNA and rates of CMV DNA detection were low (3%).

CONCLUSIONS

The study demonstrates the presence of HHV-8 in semen from HIV-infected individuals with, or at risk, of developing KS and the potential for sexual transmission of the virus. We found no evidence of HHV-8 in the semen of HIV-uninfected donors.

Molecular mimicry of human cytokine and cytokine response pathway genes by KSHV

Four virus proteins similar to two human macrophage inflammatory protein (MIP) chemokines, interleukin-6 (IL-6), and interferon regulatory factor (IRF) are encoded by the Kaposi's sarcoma-associated herpesvirus (KSHV) genome. vIL-6 was functional in B9 proliferation assays and primarily expressed in KSHV-infected hematopoietic cells rather than KS lesions. HIV-1 transmission studies showed that vMIP-I is similar to human MIP chemokines in its ability to inhibit replication of HIV-1 strains dependent on the CCR5 co-receptor. These viral genes may form part of the response to host defenses contributing to virus-induced neoplasia and may have relevance to KSHV and HIV-I interactions.

Primary, syncytium-inducing human immunodeficiency virus type 1 isolates are dual-tropic and most can use either Lestr or CCR5 as coreceptors for virus entry

A panel of primary syncytium-inducing (SI) human immunodeficiency virus type 1 isolates that infected several CD4+ T-cell lines, including MT-2 and C8166, were tested for infection of blood-derived macrophages. Infectivity titers for C8166 cells and macrophages demonstrated that primary SI strains infected macrophages much more efficiently than T-cell line-adapted HIV-1 strains such as LAI and RF. These primary SI strains were therefore dual-tropic. Nine biological clones of two SI strains, prepared by limiting dilution, had macrophage/C8166 infectivity ratios similar to those of their parental viruses, indicating that the dual-tropic phenotype was not due to a mixture of non-SI/macrophage-tropic and SI/T-cell tropic viruses. We tested whether the primary SI strains used either Lestr (fusin) or CCR5 as coreceptors. Infection of cat CCC/CD4 cells transiently expressing Lestr supported infection by T-cell line-adapted strains including LAI, whereas CCC/CD4 cells expressing CCR5 were sensitive to primary non-SI strains as well as to the molecularly cloned strains SF-162 and JR-CSF. Several primary SI strains, as well as the molecularly cloned dual-tropic viruses 89.6 and GUN-1, infected both Lestr+ and CCR5+ CCC/CD4 cells. Thus, these viruses can choose between Lestr and CCR5 for entry into cells. Interestingly, some dual-tropic primary SI strains that infected Lestr+ cells failed to infect CCR5+ cells, suggesting that these viruses may use an alternative coreceptor for infection of macrophages. Alternatively, CCR5 may be processed or presented differently on cat cells so that entry of some primary SI strains but not others is affected.

Laser capture microdissection

Laser capture microdissection (LCM) under direct microscopic visualization permits rapid one-step procurement of selected human cell populations from a section of complex, heterogeneous tissue. In this technique, a transparent thermoplastic film (ethylene vinyl acetate polymer) is applied to the surface of the tissue section on a standard glass histopathology slide; a carbon dioxide laser pulse then specifically activates the film above the cells of interest. Strong focal adhesion allows selective procurement of the targeted cells. Multiple examples of LCM transfer and tissue analysis, including polymerase chain reaction amplification of DNA and RNA, and enzyme recovery from transferred tissue are demonstrated.

Prevalence of Kaposi's sarcoma associated herpesvirus infection measured by antibodies to recombinant capsid protein and latent immunofluorescence antigen

BACKGROUND

Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8, may be the infectious cause of KS. Its prevalence in the general population, on the basis of detection of the virus genome, is controversial. To investigate the seroprevalence, we measured antibodies to a recombinant capsid-related (lytic cycle) KSHV antigen and a latent antigen complex.

METHODS

We selected potentially immunoreactive capsid-related proteins of KSHV by expressing them as recombinant proteins and testing them in western blot assays. We used a truncated recombinant protein encoded by KSHV open reading frame 65 (orf 65) to develop a diagnostic enzyme-linked immunosorbent assay (ELISA) and tested sera from HIV-infected individuals with KS, HIV-uninfected patients with "classic" KS, other HIV risk groups, and blood donors. We also compared the antibody response to this capsid-related protein to the response to latent antigen(s) in an immunofluorescence assay.

FINDINGS

77/92 (84%) sera from KS patients reacted with the KSHV orf 65 protein and 84/103 (81.5%) reacted with KSHV latent antigen(s). The dominant immunogenic region of orf 65 is within the carboxyterminal 80 aminoacids, a region with little sequence similarity to the related Epstein-Barr virus, suggesting that orf 65 is a KSHV specific antigen. Only three sera from patients with haemophilia (1/84) or from intravenous drug users (2/63) had KSHV specific antibodies in the orf 65 assay whereas none of these sera reacted with latent antigen. Antibodies to KSHV were also infrequently found in UK and US blood donors by either assay (UK, 3/174 with orf 65 and 4/150 with latent antigen; US, 6/117 with orf 65 and 0/117 with latent antigen). They were more common among HIV-infected gay men without KS (5/16 by orf 65 ELISA, 10/33 by IFA), HIV-uninfected STD clinic attenders (14/166 by IFA), and Ugandan HIV-uninfected controls (6/17 by orf 65 ELISA, 9/17 by IFA). Antibody reactivity to the orf 65 protein (ELISA) and to latent antigen(s) (IFA) was concordant in 89% of 462 sera tested but reactive blood donor sera were discordant in both assays. Four AIDS-KS sera were unreactive in both assays.

INTERPRETATION

The distribution of antibodies to both a capsid-related recombinant protein and latent antigen(s) of KSHV strongly supports the view that infection with this virus is largely confined to individuals with, or at increased risk for, KS. However, infection with KSHV does occur, rarely, in the general UK and US population and is more common in Uganda. Antibodies to latent antigen(s) or to orf 65 encoded capsid protein will not detect all cases of KSHV infection, and a combination of several antigens will probably be required for accurate screening and confirmatory assays.

HIV infection and neoplasia

HIV infection predisposes to several neoplastic conditions, especially non-Hodgkin lymphoma (NHL) and Kaposi's sarcoma (KS), and also intraepithelial cervical neoplasia (CIN) and anal neoplasia (AIN) (but not cervical or anal invasive cancer) and possibly seminoma. For neoplasias associated with oncogenic human viruses (ie, some NHL, CIN, AIN, and probably KS) the role of HIV is most probably linked to its immunosuppressive effect and interference with immune-mediated tumour surveillance. HIV-1, through its regulatory protein tat, might also have a direct promoting effect on KS lesions but it is not essential for their development. The increased frequency of Burkitt's lymphoma and Epstein-Barr-virus-negative large-cell lymphoma in AIDS patients, but not in immunosuppressed transplant patients, and the increased rate of testicular tumours in HIV-infected individuals remain unexplained and may indicate either a direct role for HIV or other cofactors.

Endogenous D-type (HERV-K) related sequences are packaged into retroviral particles in the placenta and possess open reading frames for reverse transcriptase

All primates studied to date produce retroviral-like particles in their placentae. We have purified these particles from two primate species, one Old World (human) and one New World (marmoset), and have identified the retroviral sequences which are packaged into these particles. Three families of sequences have been detected in these particles in human, all of which have the highest homology to B- and D-type retroviruses and to the human endogenous retrovirus HERV-K10. Previous studies have reported that the New World monkeys do not possess sequences with homology to HERV-K10. We have identified a new family of low-copy-number sequences which are present in New World monkeys and which possess 70% homology to the HERV-K family. Particles from both species possess reverse transcriptase activity and we have found that some of these retroviral particles package sequences which encode long open reading frames in pol, as revealed by expression cloning in Escherichia coli. These open reading frames could encode the reverse transcriptase enzyme activity found in the particles.