PubMed Health⌕ Search

Biomedical subjects

U A Gompels

Publications and source records attributed to U A Gompels.

At least 19 recordsLinked to original sources
PubMed2004

Linkage of human cytomegalovirus glycoprotein gO variant groups identified from worldwide clinical isolates with gN genotypes, implications for disease associations and evidence for N-terminal sites of positive selection.

Previously, we identified the glycoprotein gO gene, UL74, as a hypervariable locus in the human cytomegalovirus (HCMV) genome [Virology 293 (2002) 281]. Here, we analyze gO from 50 isolates from congenitally infected newborns, transplant recipients, and HIV/AIDS patients from Italy, Australia, and UK. These are compared to four gO groups described from USA transplantation patients [J. Virol. 76 (2002) 10841]. Phylogenetic analyses identified seven genotypes. Divergence between genotypes was up to 55% and within 3%. Discrete linkage was shown between seven hypervariable gO and gN genotypes, but not with gB. This suggests interactions, while gN and gO are known to form complexes with distinct conserved glycoproteins gM, gH/gL, respectively, both are involved in fusogenic entry and exit. Codon-based maximum likelihood models showed evidence for sites of positive selection. Further analyses of disease relationships should take into account these newly defined gO/gN groups.

Amino Acid Sequence↗
PubMed2000

RANTES binding and down-regulation by a novel human herpesvirus-6 beta chemokine receptor.

The human herpesvirus 6 (HHV-6) U51 gene defines a new family of betaherpesvirus-specific genes encoding multiple transmembrane glycoproteins with similarity to G protein-coupled receptors, in particular, human chemokine receptors. These are distinct from the HHV-6 U12 and HCMV US28 family. In vitro transcription and translation as well as transient cellular expression of U51 showed properties of a multiple transmembrane protein with a 30-kDa monomer as well as high m.w. aggregates or oligomers. Transient cellularly expressed U51 also appeared to form dimeric intermediates. Despite having only limited sequence similarity to chemokine receptors, U51 stably expressed in cell lines showed specific binding of the CC chemokine RANTES and competitive binding with other beta chemokines, such as eotaxin; monocyte chemoattractant protein 1, 3, and 4; as well as the HHV-8 chemokine vMIPII. In epithelial cells already secreting RANTES, U51 expression resulted in specific transcriptional down-regulation. This correlated with reduced secretion of RANTES protein into the culture supernatants. Regulation of RANTES levels may alter selective recruitment of circulating inflammatory cells that the virus can infect and thus could mediate the systemic spread of the virus from initial sites of infection in epithelia. Alternatively, chemokine regulation could modulate a protective inflammatory response to aid the spread of virus by immune evasion. Such mimicry, by viral proteins, of host receptors leading to down-regulation of chemokine expression is a novel immunomodulatory mechanism.

Amino Acid Sequence↗
PubMed1999

Novel, nonconsensus cellular splicing regulates expression of a gene encoding a chemokine-like protein that shows high variation and is specific for human herpesvirus 6.

There are few genes that are specific and diagnostic for human herpesvirus-6. U83 and U22 are two of them. U22 is unique, whereas U83 encodes distant similarity with some cellular chemokines. Reverse transcription-polymerase chain reaction, cDNA cloning, and sequence analyses show polyadenylated RNA transcripts corresponding to minor full-length and abundant spliced forms of U83 in human herpesvirus 6-infected cells. The splice donor and acceptor sites do not fit consensus sequences for either major GT-AG or minor AT-AC introns. However, the spliced form can also be detected in a U83 transfected cell line; thus the novel sites are used by cellular mechanisms. This intron may represent a new minor CT-AC splicing class. The novel splicing regulates gene expression by introducing a central stop codon that abrogates production of the chemokine-like molecule, resulting in an encoded truncated peptide. The use of metabolic inhibitors and an infection time course showed expression of the two RNA transcripts with immediate early kinetics. However, the full-length product accumulated later, dependent on virus DNA replication, similar to U22. Sequence analyses of 16 strains showed high variation (13%) in U83, with conservation of the novel splice sites. Representative strain variants had similar kinetics of expression and spliced products.

3' Untranslated Regions↗
PubMed1999

N- and C-terminal external domains of human herpesvirus-6 glycoprotein H affect a fusion-associated conformation mediated by glycoprotein L binding the N terminus.

Human herpesvirus-6 (HHV-6), like other betaherpesviruses, shows cell fusion with wild-type strains, and this cellular spread is mediated by the glycoprotein gH/gL complex. Anti-fusion monoclonal antibodies (MAbs) specific for HHV-6 glycoprotein gH inhibit infection and prevent cellular spread by syncytia formation. Reactivity of these MAbs with gH deletion mutants suggests a conserved C-terminal fusion-associated domain. A conserved motif here has an N-glycosylation site and characteristics of a beta turn. Motif deletion abrogated MAb recognition while co-expression with glycoprotein gL restored this conformational epitope, indicating the importance of folding and not glycosylation at this site. Our previous studies showed gL binding to gH at an N-terminal domain specific for betaherpesviruses. To further examine the function of this N-terminal domain, a betaherpesvirus-specific motif was deleted. This mutant gH still bound gL, and was recognized by the anti-fusion MAbs; however, recognition was now primarily in the immature form and reduced during processing to the mature form. A model is discussed whereby gL binding gH at the N-terminal domain acts to draw together the C-terminal extracellular domain and this interaction affects a functional conformation during glycoprotein maturation.

Animals↗
PubMed1998

Sequence analyses of human herpesvirus-8 strains from both African human immunodeficiency virus-negative and -positive childhood endemic Kaposi's sarcoma show a close relationship with strains identified in febrile children and high variation in the K1 glycoprotein.

Human herpesvirus-8 (HHV-8) DNA sequences have been identified in all forms of Kaposi's sarcoma (KS), a cancer found primarily in adult AIDS patients. We have identified HHV-8 strains in a rare human immunodeficiency virus (HIV)-negative form of KS, which is endemic in children in parts of sub-Saharan Africa. This was shown in Zambia, where we also had identified HHV-8 sequences in blood from HIV-negative febrile children without KS. In order to investigate the relationship of these Zambian strains to each other and to those from other forms of KS, we compared them to strains we have characterized from European AIDS KS (Denmark) and all published sequences from all forms of KS. Four distinct genomic regions were examined by PCR and sequencing: ORF26, ORF75, gH and K1. The results showed a distinct grouping of strains from both sets of Zambian children in all genomic regions studied, but which was most pronounced in the K1 glycoprotein gene. This gene was highly variable, encoding up to 25% amino acid sequence variation. In contrast, the Zambian groups were closely related to each other, with only 2% variation. Similar results were found in comparisons to the K1 sequences from HIV-positive febrile infants or KS children. The data raise the possibility that in areas where rare childhood endemic KS occurs, geographical variation in HHV-8 may relate to differences in virulence or transmission.

AIDS-Related Opportunistic Infections↗
PubMed1997

Infection with AIDS-related herpesviruses in human immunodeficiency virus-negative infants and endemic childhood Kaposi's sarcoma in Africa.

Novel herpesviruses have been described recently. These include human herpesviruses 6, 7 and 8 (HHV-6, -7, -8). HHV-6 has at least two strain groups, variants A and B. The B strains are predominant in the West and can account for over 97% of infections in infants. In contrast, the A strains are rare and the few well-characterized isolates have been from adult African AIDS patients. It is not clear whether the HHV-6 variant A strains are AIDS-related and/or whether they can also be acquired as childhood infections and may reactivate later during adulthood. What contribution geographical variation plays has yet to be assessed. HHV-8 has been associated with AIDS-related epidemic Kaposi's sarcoma (KS), but has also been identified in endemic KS. In regions of Africa where KS is endemic, the onset of AIDS has led to increased prevalence of KS. In this report, we examine in Zambia, an AIDS epidemic and KS endemic region, infection with these novel herpesviruses during infancy. In blood samples from human immunodeficiency virus-negative infants with first febrile episode, both semi-quantitative PCR and sequence analyses were used to identify HHV-8 in 8% and HHV-6 in 30%, with 44% of these variant A; in childhood endemic KS biopsies HHV-8 was detected in 100% and HHV-6 in none. The high viral-DNA loads in the infant blood samples were consistent with viraemia. This is the first demonstration that HHV-6 variant A and HHV-8 may be acquired as common childhood infections.

AIDS-Related Opportunistic Infections↗
PubMed1996

Definition of a human herpesvirus-6 betaherpesvirus-specific domain in glycoprotein gH that governs interaction with glycoprotein gL: substitution of human cytomegalovirus glycoproteins permits group-specific complex formation.

Formation of the glycoprotein gH/gL heterooligomer has important implications for understanding the pathology of human herpesvirus-6(HHV-6)-associated disease because this complex is essential for infectivity and fusogenic cell-to-cell spread. Definition of the HHV-6 gH domain involved in protein-protein interactions was addressed by targeting regions defined by conserved cysteines identified by alignment of gH amino acid sequences representative of all herpesvirus subfamilies. Studies using site-directed mutagenesis and transient cellular expression showed that the N-terminus of HHV-6 gH includes a 230-amino-acid domain required for interaction with HHV-6 gL encompassing residues conserved specifically amongst betaherpesviruses. Interestingly, the human cytomegalovirus (HCMV) homologues, UL75 (gH) or UL115 (gL), can substitute for HHV-6 glycoproteins and participate in heterologous complex formation. Furthermore, the region which governs this heterologous gL binding also maps to the N-terminal portion of HHV-6 gH. Although both proteins can functionally substitute for complex formation there are also specific differences. Surprisingly, further deletion of HHV-6 gH to 145-amino-acid-domain residues abolishes complex formation with HHV-6 gL but allows interaction with HCMV gL. This may be related to requirements in HHV-6 for homodimer formation before complex formation between gH and gL. Under nonreducing conditions HHV-6 gH and gL form multimeric complexes consistent with intra- and intermolecular dimer formation stabilised by disulphide bonds whereas for HCMV there is no evidence for dimer formation for gH and multimeric complexes have only been observed between gH and gL. In summary, both HHV-6 and HCMV glycoproteins can interact and the heterologous complex between HHV-6 gH and HCMV gL is possibly more stable. This may result in important biological consequences in vivo during cellular coinfections by facilitating spread of the viruses, with applications to altered cellular tropisms and effects on reactivation from the latently infected cell.

Base Sequence↗
PubMed1995

The DNA sequence of human herpesvirus-6: structure, coding content, and genome evolution.

The complete DNA sequence was determined for strain U1102 of human herpesvirus-6, a CD4+ T-lymphotropic virus with disease associations in immunodeficient settings and a possible complicating factor in AIDS. The genome is 159,321 bp in size, has a base composition of 43% G + C, and contains 119 open reading frames. The overall structure is 143 kb bounded by 8 kb of direct repeats, DRL (left) and DRR (right), containing 0.35 kb of terminal and junctional arrays of human telomere-like simple repeats. Since eight open reading frames are duplicated in the repeats, six span repetitive elements and three are spliced, the genome is considered to contain 102 separate genes likely to encode protein. The genes are arranged colinearly with those in the genome of the previously sequenced betaherpesvirus, human cytomegalovirus, and has a distinct arrangement of conserved genes relative to the sequenced gammaherpesviruses, herpesvirus saimiri and Epstein-Barr virus, and the alphaherpesviruses, equine herpesvirus-1, varicella-zoster virus, and herpes simplex virus. Comparisons of predicted amino acid sequences allowed the functions of many human herpesvirus-6 encoded proteins to be assigned and showed the closest relationship in overall number and similarity to human cytomegalovirus products, with approximately 67% homologous proteins as compared to the 21% identified in all herpesviruses. The features of the conserved genes and their relative order suggested a general scheme for divergence among these herpesvirus lineages. In addition to the "core" conserved genes, the genome contains four distinct gene families which may be involved in immune evasion and persistence in immune cells: two have similarity to the "chemokine" chemotactic/proinflammatory family of cytokines, one to their peptide G-protein-coupled receptors, and a fourth to the immunoglobulin superfamily.

AIDS-Related Opportunistic Infections↗
PubMed1995

Characterization of human telomeric repeat sequences from human herpesvirus 6 and relationship to replication.

Here we examine by polymerase chain reaction amplification followed by cloning and sequence analyses selected regions of the human herpesvirus 6 (HHV-6) genome which contain human telomeric repeats (TTA-GGG). We determine the relative number, arrangement and orientation of the repeats in the unit length genome, in concatemeric replicative intermediates and in heterogeneous (het) regions. We also examine distribution of the repeats in the entire genome (159 kb) and their orientation relative to DNA packaging motifs and the origin of lytic replication. In the prototype orientation the HHV-6 repeat is the related complement, TAACCC. We show that tandem arrays of this repeat are present in the right and left long direct repeats (DRL and DRR, 8 kb each) which bound the long unique sequence (UL, 143 kb). Within each DR there is a left terminal imperfect tandem array and a right terminal perfect tandem array (58 copies). In DR they are each adjacent to DNA packaging motifs, pac1 and pac2, described for herpes simplex virus and human cytomegalovirus, in the arrangement pac1-imperfect repeat-7.2 kb-perfect repeat-pac2. Five independent clones were isolated and sequence determined from junctions of concatemeric replicative intermediates which showed adjacent pac2 and pac1 motifs surrounded by telomeric repeats. Favoured cleavage sites for unit length genomes were indicated which avoided cleavage within the repeats. Analyses of the complete genome showed no tandem repeats within UL but did show a polar distribution of monomeric copies and related sequences around the origin of replication, with an effect on the overall base composition. The implications for virus replication are discussed.

Amino Acid Sequence↗
PubMed1993

Human herpesvirus-6 glycoprotein H and L homologs are components of the gp100 complex and the gH external domain is the target for neutralizing monoclonal antibodies.

Previous studies have shown that monoclonal antibody (MAb) 2E4 neutralizes infectivity of human herpesvirus-6 (HHV-6) and also inhibits virus-induced T-lymphocyte syncytia formation. Here we characterize two additional MAbs, 1D3 and 5E7, which have similar properties, and identify the glycoprotein targets. The MAbs could immunoprecipitate and immunofluorescence glycoprotein from both A and B variant strain groups of HHV-6. In reactions with infected cells the MAbs immunoprecipitated a complex of glycoproteins, the "gp100" complex, composed of a major glycoprotein species of 100,000 M(r) and minor components of 80,000 M(r) and 32,000 M(r). We show that the 100,000 M(r) product and most likely the 80,000 M(r) correspond to the HHV-6 homologue of herpes simplex virus-1 (HSV-1) glycoprotein H (gH) while the 32,000 M(r) species corresponds to the glycoprotein L (gL) equivalent. All three MAbs could specifically immunoprecipitate either gH expressed on its own in fibroblasts or a complex of gH and gL co-expressed, but could not immunoprecipitate gL expressed on its own. Consistent with these results, the MAbs could recognize gH in an immunofluorescence assay but not gL. Therefore although the MAbs recognized the complex of glycoproteins, they appeared specific for gH. The HHV-6 glycoproteins were produced in a transient expression system induced by T7-vaccinia virus. Immunoprecipitations were carried out in comparisons with an "epitope-tagged" gH, a recombinant glycoprotein designed to contain at the N-terminus the linear epitope for MAb LP14, raised originally against HSV-1 glycoprotein gD. The epitope-tagged gH was also used as a positive control in determining the domain of HHV-6 gH to which MAbs 2E4, 1D3 and 5E7 were directed. Two gH deletions were constructed, one deleting sequences which may serve as a transmembrane and cytoplasmic anchor domains, the second deleting also part of the external domain. MAb LP14 could immunoprecipitate both HHV-6 gH deletions but the gp100 MAbs recognized only the full-length product or the intact external domain minus the transmembrane and cytoplasmic domains. This indicated the epitopes for these MAbs are contained in the external domain of gH, consistent with the MAbs action in neutralization of virion infectivity and inhibition of virus to cell spread by T-lymphocyte fusion.

Amino Acid Sequence↗
PubMed1993

Two groups of human herpesvirus 6 identified by sequence analyses of laboratory strains and variants from Hodgkin's lymphoma and bone marrow transplant patients.

Fifteen human herpesvirus 6 (HHV-6) strain variants were analysed by PCR amplifications, restriction enzyme site polymorphism and sequence analyses. Three DNA regions were chosen for study: a fragment of a variable glycoprotein gene (210 bp), the conserved glycoprotein H (gH) gene complete with intergenic sequences (2381 bp) and the 5' intergenic region with the N-terminal coding sequence of gH up to a polymorphic BamHI site (427 bp). Infected cell DNA from five laboratory reference strains including GS, U1102, AJ, Z29 and KF were examined together with DNA from peripheral blood lymphocytes infected with HHV-6 reactivated from blood and/or marrow from five bone marrow transplant (BMT) patients. Separate blood and marrow isolates were obtained from four BMT patients. In addition, HHV-6 sequences were examined directly from one of six Hodgkin's lymphomas and six B cell proliferations which contained HHV-6 DNA as detected by PCR amplification. The results show two groups of very closely related but heterogeneous strains which correlate with previous groupings by antigenic and restriction site differences. These are variant A strains (including laboratory strains GS, U1102 and AJ) and variant B strains (including laboratory strains Z29 and KF, the Hodgkin's lymphoma strain, and the nine BMT patient isolates). Variations between the groups were 4 to 6% in nucleotide sequence and 5 to 8.5% in amino acid sequence. Within each group maximum heterogeneity was observed in different genes. Variant A strains differed by 2.0% in the variable glycoprotein gene sequence whereas variant B strains were identical in this region; conversely, variant B strains differed by 2 to 3% in the gH N-terminal and intergenic sequences whereas variant A strains differed there by less than 0.2%. There was evidence for sequence drift independent of selection: relationships between the groups were shown by analyses of amino acid sequence, coding nucleotide sequence as well as intergenic sequence, and the B variant-specific BamHI site in the gH gene was due to a non-coding nucleotide substitution. There was little evidence for in vivo or in vitro variation: the gH nucleotide sequence from the uncultured lymphoma strain (first variant B gH gene identified) was almost identical to the gH sequence from four BMT isolates, and matched BMT isolates from blood and marrow were identical or with a single nucleotide substitution.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1993

Identification and expression of the human herpesvirus 6 glycoprotein H and interaction with an accessory 40K glycoprotein.

In herpes simplex virus (HSV) the small secreted glycoprotein gL forms a heterodimer with the transmembrane envelope glycoprotein gH. Here we identify the human herpesvirus 6 (HHV-6) gL gene, express HHV-6 gL and gH homologues, and examine interactions between HHV-6 gH and gL. The HHV-6 gL gene encoded a glycoprotein with an amino acid sequence which showed closest similarity to the human cytomegalovirus (HCMV) gL homologue (18% identity). Products of HHV-6 gH and gL genes were characterized in an in vitro transcription-translation system and in a transient in vivo expression system. Both gH and gL were transcribed and translated in vitro to give products of apparent M(r) of 65K and 28K in SDS-PAGE, and these could be processed by addition of microsomes to 110K and 40K, respectively. To study gH/gL interactions, gH was tagged with the nine amino acid epitope for monoclonal antibody LP14 (anti-HSV-1 gD). LP14 and a human serum sample specifically immunoprecipitated gH and a stable complex of gH and gL co-expressed in an in vivo vaccinia virus-T7 system. The gH and gL produced in this in vivo expression system corresponded to the M(r)s of the fully processed glycoproteins identified in the in vitro system. The gH expressed together with gL was recognized by human sera more easily than when examined on its own in immunofluorescence assays. Dual expression of gH and gL in transfected T lymphocytes (JJhan) caused reactions with 75% of human sera tested (12 HHV-6-positive, HCMV-negative serum samples), but gL expressed alone was not recognized by these sera. The immunofluorescence studies also showed that the glycoproteins were localized in Golgi-like bodies in fibroblasts, but occurred throughout the endoplasmic reticulum in T lymphocytes, the normal cellular target for HHV-6. These results show the identification of the HHV-6 homologue to the HCMV and HSV gL genes, identification and production of HHV-6 gH and gL expressed both in vitro and in vivo, complex formation between these glycoproteins, and evidence that this complex may be localized differently in fibroblasts as compared to T lymphocytes and that it is immunogenic.

Adult↗
PubMed1992

Glycoprotein H of human cytomegalovirus (HCMV) forms a stable complex with the HCMV UL115 gene product.

The human cytomegalovirus (HCMV) UL75 gene product is the homologue of herpes simplex virus type 1 (HSV-1) glycoprotein H (gH), a virion glycoprotein that is essential for infectivity and which is conserved among members of the alpha-, beta- and gamma-herpesviruses. It has previously been shown that HSV-1 gH forms a stable complex with HSV-1 gL, the product of the UL1 gene, and the formation of this complex facilitates the cell surface expression of gH. None of the open reading frames within the HCMV genome encode a product with discernible sequence homology with HSV-1 gL, but an examination of the arrangement of conserved genes in HCMV suggested that the UL115 gene is a 'positional homologue' of HSV-1 UL1 which, like UL1, encodes a small secreted glycoprotein. Co-expression of HCMV gH (the UL75 gene product) and the UL115 gene product revealed that these proteins form a disulphide-linked complex and that the formation of this complex results in cell surface expression of gH. This complex is analogous to the gH:gL complex of HSV-1 and the HCMV UL115 gene product is therefore the functional homologue of HSV-1 gL.

Cells, Cultured↗
PubMed1992

Infectivity determinants encoded in a conserved gene block of human herpesvirus-6.

The nucleotide sequence was determined for a 9.3 kb BamHI DNA fragment derived from a cosmid clone (Lorist 6) library of the 160 kb human herpesvirus-6 (HHV-6) strain U1102 genome. Analysis of the sequence showed two different sources for the DNA; 8.0 kb was derived from HHV-6, while 1.3 kb was derived from the right repeat of transposon Tn10, the insertion sequence (IS) element IS10R. The IS element sequence is shown to be derived from the host bacteria of the plasmid. The HHV-6 sequence represents a highly conserved part of the genome encoding 15% of the genes conserved among the other human herpesviruses in only 5% of the genome. Six genes were identified, five encoding products with amino acid sequence similarity to homologues in herpes simplex virus (HSV), Varicella Zoster Virus (VZV), human cytomegalovirus (CMV) and Epstein-Barr Virus (EBV). All had closest amino acid similarity to CMV proteins. Three clustered structural genes, included glycoprotein H, a major conserved determinant of infectivity, were jointed to a putative dUTPase homologue in an arrangement distinct to CMV and HHV-6. In the other herpes viruses these genes are separated by over 50 kb. The gene at this point of genetic rearrangement had no sequence similarity to proteins of other herpesviruses. However, there is a protein at this locus in CMV with similar composition and character. Both appear to be highly glycosylated, secreted glycoproteins with repetitive elements similar to those of human mucins. Comparison of sequence available in the HHV-6 GS strain also shows this to be a variable region (5% nucleotide differences) in an overall conserved DNA sequence (0.5%).

Amino Acid Sequence↗
PubMed1991

The genome of human herpesvirus 6: maps of unit-length and concatemeric genomes for nine restriction endonucleases.

More than 50 fragments resulting from complete digestion of the DNA of human herpesvirus 6 (HHV-6, strain U1102) with BamHI, EcoRI, HindIII, KpnI, NruI, SalI or SmaI have been isolated as clones in M13, plasmid, cosmid and lambda vectors. Using these clones, maps have been constructed for the fragments produced by nine restriction enzymes from unit-length virus genomes and from their concatemeric precursors. The unit-length genome is a linear, double-stranded molecule of 161.5 kbp composed of a central segment of a largely unique sequence of 141 kbp (U) with a sequence of 10 kbp duplicated in the same orientation at both 'left' and 'right' genomic termini (i.e. 'left' and 'right' copies of the direct repeat; DRL and DRR). Adopting as standard an orientation in which the major capsid protein gene is 'left' of the gene for alkaline exonuclease, then the 'right' genome termini and DRL. U junctions occur close to or within repetitive (GGGTTA)n sequences. Repetitions of short sequence motifs are present in at least two other regions of the genome. One of these regions consists of a simple repeat (TC/G) of approximately 1.5 kbp in length and is unstable as clones in bacterial vectors. The second region is stably maintained in such vectors and consists of a tandem array of at least 25 copies of a 110 bp sequence containing a single KpnI site. Comparisons of fragments arising from unit-length DNA with those from virus DNA from the nuclei of infected cells have shown that the concatemeric junctions in intracellular DNA contain head-to-tail dimers of the terminal duplications (i.e. ...U1.DRR1.DRL2.U2...). The gross structure established here for the genome from the U1102 isolate of HHV-6 resembles closely that suggested by Pellett and his colleagues for the Z29 isolate and differs from that of the five previously characterized human herpesviruses. This structure of HHV-6 DNA bears a superficial resemblance to that proposed for DNA from channel catfish virus and equine cytomegalovirus.

Base Sequence↗
PubMed1991

Characterization and sequence analyses of antibody-selected antigenic variants of herpes simplex virus show a conformationally complex epitope on glycoprotein H.

Thirteen antigenic variants of herpes simplex virus which were resistant to neutralization by monoclonal antibody 52S or LP11 were isolated and characterized. The antibodies in the absence of complement potently neutralize infectivity of wild-type virus as well as inhibit the transfer of virus from infected to uninfected cells ("plaque inhibition") and decrease virus-induced cell fusion by syncytial strains. The first variant isolated arose in vivo. Of 66 type 1 isolates analyzed from typing studies of 100 clinical isolates, one was identified as resistant to neutralization by LP11 antibody. The glycoprotein H (gH) sequence was derived and compared with those of wild-type and syncytial laboratory strains SC16, strain 17, and HFEM. The sequences were highly conserved in contrast to the diversity observed between gH sequences from herpesviruses of different subgroups. Only four coding changes were present in any of the comparisons, and only one unique coding change was observed between the laboratory strains and the clinical isolate (Asp-168 to Gly). These sequences were compared with those of antigenic variants selected by antibody in tissue culture. Twelve variants were independently selected with antibody LP11 or 52S from parent strain SC16 or HFEM. For each variant, the gH nucleotide sequence was derived and a point mutation was identified giving rise to a single amino acid substitution. The LP11-resistant viruses encoded gH sequences with amino acid substitutions at sites distributed over one-half of the gH external domain, Glu-86, Asp-168, or Arg-329, while the 52S-resistant mutant viruses had substitutions at adjacent positions Ser-536 and Ala-537. One LP11 mutant virus had a point mutation in the gH gene that was identical to that of the clinical isolate, giving rise to a substitution of Asp-168 with Gly. Both LP11 and 52S appeared to recognize distinct gH epitopes as mutant virus resistant to neutralization and immunoprecipitation with LP11 remained sensitive to 52S and the converse was shown for the 52S-resistant mutant virus. This is consistent with previous studies which showed that while the 52S epitope could be formed in the absence of other virus products, virus gene expression was required for stable presentation of the LP11 epitope, and for transport of gH to the cell surface (Gompels and Minson, J. Virol. 63:4744-4755, 1989). All mutant viruses produced numbers of infectious particles that were similar to those produced by the wild-type virus, with the exception of one variant which produced lower yields.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acids↗