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Biomedical subjects

H M Friedman

Publications and source records attributed to H M Friedman.

At least 37 records · Page 2Linked to original sources
PubMed1996

Immune evasion properties of herpes simplex virus type 1 glycoprotein gC.

Herpes simplex virus type I (HSV-1) glycoprotein gC binds complement component C3b, and purified gC inhibits complement activation. Two HSV strains carrying mutations in the gC gene which rendered them unable to bind C3b were compared with wild-type and marker-rescued viruses to evaluate the role of gC on the virion in protecting HSV-1 from complement-mediated neutralization. The gC mutant viruses were markedly susceptible to neutralization by nonimmune human serum, showing up to a 5,000-fold decline in titer after 1 h of incubation with serum. In contrast, wild-type or marker-rescued viruses showed a twofold reduction in titer. Studies with hypogammaglobulinemic and immunoglobulin G-depleted serum supported the observation that neutralization occurred in the absence of antibody. Neutralization of gC mutant strains by nonimmune serum was rapid; their half-life was 2 to 2.5 min, compared with 1 h for wild-type virus. Ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)-treated human serum or C4-deficient guinea pig serum failed to neutralize gC mutant strains, indicating a role for components of the classical complement pathway. gC had little additional effect on neutralization by the combination of antibody plus complement compared with complement alone. The results indicate that the magnitude of the protection offered by gC-1 is larger than previously recognized; that in the absence of gC-1, complement neutralization is rapid and is mediated by components of the classical complement pathway; and that gC mainly protects against antibody-independent complement neutralization, suggesting a probable role for gC early in infection, before antibodies develop.

Animals↗
PubMed1996

Disulfide bond structure determination and biochemical analysis of glycoprotein C from herpes simplex virus.

A biochemical analysis of glycoprotein C (gC of herpes simplex virus was undertaken to further characterize the structure of the glycoprotein and to determine its disulfide bond arrangement. We used three recombinant forms of gC, gC1(457t), gC1(delta33-123t), and gC2(426t), each truncated prior to the transmembrane region. The proteins were expressed and secreted by using a baculovirus expression system and have been shown to bind to monoclonal antibodies which recognize discontinuous epitopes and to complement component C3b in a dose-dependent manner. We confirmed the N-terminal residues of each mature protein by Edman degradation and confirmed the internal deletion in gC1(delta33-123t). The molecular weight and extent of glycosylation of gC1 (457t), gC1(delta33-123t), and gC2(426t) were determined by treating each protein with endoglycosidases and then subjecting it to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometric analysis. The data indicate that eight to nine of the predicted N-linked oligosaccharide sites on gC1(457t) are occupied by glycans of approximately 1,000 Da. In addition, O-linked oligosaccharides are present on gC1(457t), primarily localized to the N-terminal region (amino acids [aa] 33 to 123) of the protein. gC2(426t) contains N-linked oligosaccharides, but no O-linked oligosaccharides were detected. To determine the disulfide bond arrangement of the eight cysteines of gC1(457t),the protein was cleaved with cyanogen bromide. SDS-PAGE analysis followed by Edman degradation identified three cysteine-containing fragments which are not connected by disulfide linkages. Chemical modification of cysteines combined with matrix-assisted laser desorption ionization mass spectrometry identified disulfide bonds between cysteine 1 (aa 127) and cysteine 2 (aa 144) and between cysteine 3 (aa 286) and cysteine 4 (aa 347). Further proteolysis of the cyanogen bromide-generated fragment containing cysteine 5 through cysteine 8, combined with mass spectrometry and Edman degradation, showed that disulfide bonds link cysteine 5 (aa 386) to cysteine 8 (aa 442) and cysteine 6 (aa 390) to cysteine 7 (aa 419). A similar disulfide bond arrangement is postulated to exist in gC homologs from other herpesviruses.

Amino Acid Sequence↗
PubMed1995

Evidence of active cytomegalovirus infection in clinically stable HIV-infected individuals with CD4+ lymphocyte counts below 100/microliters of blood: features and relation to risk of subsequent CMV retinitis.

To determine the frequency and significance of cytomegalovirus (CMV) viremia and viruria in HIV-positive subjects with low CD4+ lymphocyte counts but with no clinical indications for culture, we studied 100 consecutive clinically stable subjects with CD4+ cells < or = 100/microliters of blood who agreed to culture of blood and urine. Serum was tested for CMV antibody, p24 antigen, neopterin, and liver enzyme concentrations, and patients were offered funduscopic examination. Subjects' records were reviewed an average of 9.1 months after enrollment for evidence of subsequent CMV retinitis. Three of the original cohort proved ineligible because of CD4+ count > 100/microliters; CMV antibody was present in 96% of the remainder. Isolation of CMV from blood was uncommon (2 of 93 seropositive subjects) whereas viruria occurred in 51.6%; likelihood of having a positive urine culture was significantly related to the subject's absolute CD4+ lymphocyte count: 60% for those with CD4+ < or = 50/microliters, vs. 26.1% for those with CD4+ 51-100/microliters. Neither serum p24 antigen nor neopterin was predictive of CMV in urine or blood. No subjects submitting to ophthalmologic exam had unsuspected CMV retinitis. Subsequent development of retinitis correlated with CMV viruria on entry: 13.5% if urine-positive, 1.9% if negative (p = 0.029; Fisher exact test).

Adult↗
PubMed1995

Characterization of regions of herpes simplex virus type 1 glycoprotein E involved in binding the Fc domain of monomeric IgG and in forming a complex with glycoprotein I.

Glycoprotein E (gE) and glycoprotein I (gI) of herpes simplex virus type 1 form a molecular complex that binds the Fc domain of monomeric IgG. Two approaches were used to define regions of gE-1 involved in monomeric IgG binding and complex formation with gI-1. First, we constructed 22 in-frame gE-1 linker-insertion mutants and, in cotransfection experiments with gI-1, assayed each mutant for IgG monomer binding and the ability to complex with gI-1. Nine mutants with insertions between gE-1 amino acids 235 and 380 failed to bind IgG monomers, whereas mutants outside this region retained binding activity. Each mutant reacted with several gE-1 mAbs, was detected at the cell surface, and was fully processed. Only two gE-1 mutants with insertions at residues 235 and 264 lost the ability to co-immunoprecipitate with gI-1, which defines a region of gE-1 that complexes with gI-1. As an additional approach, we assayed 8 gE-1/gD-1 fusion proteins containing large overlapping gE-1 peptides inserted within the ectodomain of gD-1 for binding of IgG monomers and complex formation with gI-1. Three fusion proteins containing gE-1 peptides that overlap at residues 183-402 bound monomeric IgG. This region of gE-1 includes the Fc binding region defined by linker insertion mutagenesis. Five fusion proteins containing gE-1 peptides that overlap at residues 183-288 were co-immunoprecipitated with gI-1, confirming results of gE-1 linker insertion mutagenesis. These studies define two regions on gE-1 involved in Fc binding activity, one that interacts with gI-1, and another that binds IgG.

Amino Acid Sequence↗
PubMed1995

Relationship of oral disease to the presence of cytomegalovirus DNA in the saliva of AIDS patients.

Cytomegalovirus is an important pathogen in persons infected with human immunodeficiency virus. In this study a thorough oral examination was done and blood and urine cultures for cytomegalovirus were obtained from a group of 31 patients with acquired immunodeficiency syndrome with CD4 lymphocyte counts less than 150 cells/mm3. Whole saliva was also collected for detection of cytomegalovirus deoxyribonucleic acid (DNA) via the polymerase chain reaction. The presence of cytomegalovirus DNA in the saliva specimens was not related to the presence of cytomegalovirus in the urine, which suggests a local source of cytomegalovirus from salivary gland and kidney parenchyma. There was also a strong statistical relationship between salivary cytomegalovirus DNA and xerostomia (p = 0.0004), which suggests that cytomegalovirus may be a cause of salivary gland dysfunction in patients with acquired immunodeficiency syndrome with low CD4 counts.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Infection due to parvovirus B19 in patients infected with human immunodeficiency virus.

Parvovirus B19 has been described as a cause of chronic anemia in immunosuppressed patients, including those infected with human immunodeficiency virus (HIV). In this study serological assays and the polymerase chain reaction (PCR) were used to establish the prevalence of both prior and active infection due to parvovirus B19 among a general population of 105 HIV-infected individuals (cohort I) and among 22 HIV-infected patients with anemia (cohort II). Eight individuals in cohort I (7.6%) had IgG antibodies to parvovirus B19, while none had B19-specific IgM antibodies. In cohort II, four patients (18.2%) had B19-specific IgG antibodies and none had IgM antibodies. Only one person in cohort I (0.95%) and one person in cohort II (4.5%) had evidence on PCR of persistent infection with parvovirus B19; both of these patients lacked IgG and IgM antibodies to parvovirus. Both individuals with B19 viremia were anemic and had CD4 lymphocyte counts suggesting advanced immunosuppression (< 50/mm3). The observed low prevalences of B19 seropositivity and active B19 infection differ from the rates documented in previous studies and indicate that infection with parvovirus B19 is uncommon in some groups of HIV-infected patients.

AIDS-Related Opportunistic Infections↗
PubMed1995

Failure of culture and polymerase chain reaction to detect human immunodeficiency virus (HIV) in seronegative steady sexual partners of HIV-infected individuals.

Because of concern that steady sexual partners of patients infected with human immunodeficiency virus (HIV) may be infected despite negative results in tests for antibody to HIV, we studied 50 sexually active couples with discordant antibody results, assessing the agreement between these serological results and those obtained by p24 antigen testing, the polymerase chain reaction (PCR), and culture. Forty-nine of 50 seropositive sexual partners were also positive for HIV by PCR; the remaining seropositive partner was positive by culture. All seronegative partners also had negative results in the other three tests. Moreover, seronegative partners continued to have negative results in all tests for a mean follow-up period of 17 months despite ongoing sexual relations with their seropositive partners. Seronegative infection was not documented in these partners at risk for sexual transmission of HIV. HIV-negative individuals in stable, monogamous sexual relationships with HIV-infected partners apparently do not have a high incidence of infection despite continued sexual exposure.

Adult↗
PubMed1994

The interaction of glycoprotein C of herpes simplex virus types 1 and 2 with the alternative complement pathway.

Glycoprotein C (gC) of herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) binds the human complement fragment C3b, but the two proteins differ in their ability to bind C3b on infected cell surfaces. In addition, gC-1, but not gC-2, accelerates the decay of the alternative pathway C3 convertase, thereby affecting later steps of the complement cascade. Previously, we constructed linker insertion and deletion mutants of gC-1 and gC-2 and used transient transfection to express mutant proteins in uninfected cells. In spite of the differences between gC-1 and gC-2, C3b binding was localized to residues within the central portion of both proteins, encompassing the first four cysteines. For gC-1, deletion mutants lacking amino acids 33 to 123 or 367 to 469 or lacking both regions still bound C3b. We recombined these deleted forms of gC-1 into gC-39, an HSV-1 strain lacking the gC gene. The altered forms of gC-1 were incorporated into virions, expressed on the surface of infected cells, and bound C3b. We used these proteins to investigate the structural basis for the inhibitory action of gC-1 on the complement cascade. We found that gC-1 does not inhibit formation of the alternative pathway C3 convertase. This convertase is stabilized by the serum protein properdin. Purified gC-1, but not gC-2, inhibits the binding of properdin to C3b, suggesting that this destabilizes the convertase. The mutant lacking amino acids 367 to 449 was able to inhibit properdin binding to a limited extent when present at high concentrations, although it bound to C3b more weakly than wild-type gC. In contrast, the protein lacking amino acids 33 to 123 was unable to inhibit properdin binding to C3b. Thus, gC-1 contains two structural domains, one for C3b binding, residues 124 to 366, and another, residues 33 to 133, which interferes with properdin binding to C3b.

Animals↗
PubMed1994

Characterization of domains of herpes simplex virus type 1 glycoprotein E involved in Fc binding activity for immunoglobulin G aggregates.

Herpes simplex virus type 1 glycoproteins gE and gI form receptors for the Fc domain of immunoglobulin G (IgG) which are expressed on the surface of infected cells and on the virion envelope and which protect the virus from immune attack. Glycoprotein gE-1 is a low-affinity Fc receptor (FcR) that binds IgG aggregates, while gE-1 and gI-1 form a complex which serves as a higher-affinity FcR capable of binding IgG monomers. In this study, we describe two approaches used to map an Fc binding domain on gE-1 for IgG aggregates. First, we constructed nine plasmids encoding gE-1/gD-1 fusions proteins, each containing a large gE-1 peptide inserted into the ectodomain of gD-1. Fusion proteins were tested for FcR activity with IgG-sensitized erythrocytes in a rosetting assay. Three of the fusion proteins containing overlapping gE-1 peptides demonstrated FcR activity; the smallest peptide that retained Fc binding activity includes gE-1 amino acids 183 to 402. These results indicate that an Fc binding domain is located between gE-1 amino acids 183 and 402. To more precisely map the Fc binding domain, we tested a panel of 21 gE-1 linker insertion mutants. Ten mutants with insertions between gE-1 amino acids 235 and 380 failed to bind IgG-sensitized erythrocytes, while each of the remaining mutants demonstrated wild-type Fc binding activity. Taken together, these results indicate that the region of gE-1 between amino acids 235 and 380 forms an FcR domain. A computer-assisted analysis of the amino acid sequence of gE-1 demonstrates an immunoglobulin-like domain contained within this region (residues 322 to 359) which shares homology with mammalian FcRs.

Amino Acid Sequence↗
PubMed1993

HIV in the oral cavity: virus, viral inhibitory activity, and antiviral antibodies: a review.

Although it is generally assumed that HIV transmission does not occur through casual oral contact, persistent reports in the literature and the well-documented case of the Florida dentist (Ou et al., 1992) have served to elevate concerns and interest about the possibility of oral transmission of HIV. The literature suggests that: (1) the presence of infectious virus in the oral cavity is an uncommon event; (2) PCR data indicate that HIV sequences may be present in the oral cavity at reasonably high frequency--further studies are warranted; (3) saliva appears to contain potent anti-HIV activity that may be responsible for the low oral virus titer; and (4) oral secretions are a reliable source for monitoring anti-HIV antibodies. It is clear that the oral cavity will remain a focus for HIV research, in terms of both viral transmission/pathogenesis and for noninvasive diagnosis of the HIV-positive individual.

Antiviral Agents↗
PubMed1992

Structural basis of C3b binding by glycoprotein C of herpes simplex virus.

Glycoproteins C (gC) from herpes simplex virus type 1 (HSV-1) and HSV-2, gC-1 and gC-2, bind the human complement fragment C3b, although the two glycoproteins differ in their abilities to act as C3b receptors on infected cells and in their effects on the alternative complement pathway. Previously, we identified three regions of gC-2 (I, II, and III) which are important for C3b binding. In this study, our goal was to identify C3b-binding sites on gC-1 and to continue our analysis of gC-2. We constructed a large panel of mutants by using the cloned gC-1 and gC-2 genes. Most of the mutant proteins were transported to the surface of transiently transfected L cells and reacted with one or more monoclonal antibodies to discontinuous epitopes. By using 31 linker insertion mutants spread across the coding region of gC-1, we identified four regions in the ectodomain of gC-1 which are important for C3b binding, three of which are similar in position to C3b-binding regions I, II, and III of gC-2. Region III shares some similarities with the short consensus repeat found in CR1, the human complement receptor. These were, in part, the targets for construction of 20 single amino acid changes in region III of gC-1 and gC-2. These mutants identified similarities and differences in the C3b-binding properties of gC-1 and gC-2 and suggest that the amino half of region III is more important for C3b binding. However, our results do not support the concept of a structural relationship between the short consensus repeat of CR1 and gC, since mutations of some of the conserved residues, including three of four cysteines in region III, had no effect on C3b binding. Finally, we constructed four deletion mutants of gC-1, including one which lacked residues 33 to 123, as well as residues 367 to 449. This severely truncated molecule, lacking four cysteines and five potential N-linked glycosylation sites, was transported to the cell surface and retained its ability to bind monoclonal antibodies as well as C3b. Thus, the four distinct C3b-binding regions of gC-1 and several epitopes within two different antigenic sites are localized within residues 124 to 366.

Amino Acid Sequence↗
PubMed1991

Effect of Towne live virus vaccine on cytomegalovirus disease after renal transplant. A controlled trial.

OBJECTIVE: To test the efficacy of vaccination with the Towne live attenuated cytomegalovirus vaccine. DESIGN: A double-blind, randomized, placebo-controlled trial in candidates for renal transplantation. The cytomegalovirus serologic status of both recipients and donors were determined, and the recipients were followed for periods of 6 months to 7 years after transplant. SETTING: A university transplant center. PATIENTS: The analyses were made on 237 patients who were given either vaccine or placebo, received renal transplants, and were followed for at least 6 months. INTERVENTION: Subcutaneous inoculation with Towne live attenuated virus or with placebo. MAIN OUTCOME MEASURES: The presence of cytomegalovirus infection was defined by virus isolation and antibody tests. If infection occurred, a prearranged scoring system for cytomegalovirus disease was used to objectify disease severity. RESULTS: The vaccine was well tolerated, and there were no discernible long-term adverse effects. Recipients who were originally seropositive did not clearly benefit from vaccination. Protective efficacy was analyzed in the group at highest risk for cytomegalovirus disease; recipients who were seronegative at the time of vaccination and who received a kidney from a seropositive donor. Compared with placebo recipients, vaccinated patients in this group had significantly less severe cytomegalovirus disease, with a significant reduction in disease scores (P = 0.03) and 85% decrease in the most severe disease (95% CI, 35% to 96%), although infection rates were similar. Graft survival at 36 months was improved in vaccinated recipients of cadaver kidneys (8 of 16) compared with unvaccinated recipients (4 of 16) (P = 0.04). CONCLUSIONS: Previous vaccination of seronegative renal transplant recipients with live cytomegalovirus results in reduction of disease severity mimicking the action of naturally derived immunity.

Adult↗
PubMed1991

Entry of human immunodeficiency virus-1 into glial cells proceeds via an alternate, efficient pathway.

Although the CD4 molecule is the cellular receptor for human immunodeficiency virus-1 (HIV-1) in cells of the lymphocyte/monocyte lineage, a number of investigators have also been able to infect cells, including several of central nervous system (CNS) origin, that do not express CD4 protein or mRNA. These infections are generally nonpermissive. To ascertain whether the nonpermissive nature of infection in glial cells is due to an inefficient entry pathway, we prepared a permanently transfected U373-MG cell line expressing the CD4 molecule and demonstrated that HIV-1 still replicates at a low level. Furthermore, a virus uptake assay indicated that HIV-1 enters glial cells effectively, even in the absence of CD4. These results demonstrate that HIV-1 entry is efficient and that the restrictive nature of the infection in glial cells is due to postentry mechanisms. In addition, these findings support the existence of an alternate, efficient, entry pathway in some glial cells.

Blotting, Western↗
PubMed1991

Herpes simplex virus glycoprotein C is a receptor for complement component iC3b.

Herpes simplex virus type 1-infected cells bind C3b and iC3b, but not C3d, at the cell surface. Herpes simplex virus type 2 (HSV-2)-infected cells bind none of these C3 fragments. A transfection assay was used to demonstrate that binding of iC3b was to gC1. Although iC3b did not bind to HSV-2-infected cells, it did bind to mammalian cells transfected with the gC2 gene. Using linker insertion mutants, three domains on gC2 that are important for binding iC3b were mapped; these regions were similar to previously defined regions involved in binding C3b. These results suggest that some of the functions served by gC may be similar to those of CR3, the mammalian receptor for iC3b.

Amino Acid Sequence↗
PubMed1991

Herpes simplex virus type 1 Fc receptor protects infected cells from antibody-dependent cellular cytotoxicity.

Recent studies indicate that the herpes simplex virus type 1 (HSV-1) Fc receptor (FcR) can bind antiviral immunoglobulin G by participating in antibody bipolar bridging. This occurs when the Fab domain of an immunoglobulin G molecule binds to its antigenic target and the Fc domain binds to the HSV-1 FcR. In experiments comparing cells infected with wild-type HSV-1 (NS) and cells infected with an FcR-deficient mutant (ENS), we demonstrate that participation of the HSV-1 FcR in antibody bipolar bridging reduces the effectiveness of antibody-dependent cellular cytotoxicity.

Animals↗