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Biomedical subjects

A C Minson

Publications and source records attributed to A C Minson.

At least 19 recordsLinked to original sources
PubMed1992

Conservation of HPV-16 E6/E7 ORF sequences in a cervical carcinoma.

A cervical carcinoma that contained human papillomavirus (HPV)-16 homologous DNA was analyzed. Each tumor cell genome contained a single, incomplete copy of HPV-16 DNA. The E6 and E7 open reading frames (ORFs) were completely conserved relative to other published HPV-16 sequences. Much of the non-coding region (NCR) was free of base changes, including complete conservation of several regulatory elements. Multiple mutations were identified in the remaining integrated HPV-16 DNA, which was composed of parts of the L1 and E1 ORFs. The extraordinary conservation of the E6/E7 DNA sequence, as compared with other regions of the integrated HPV-16 DNA, supports the role of E6/E7 in tumorigenesis.

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

A novel herpes simplex virus glycoprotein, gL, forms a complex with glycoprotein H (gH) and affects normal folding and surface expression of gH.

A glycoprotein encoded by the UL1 gene of herpes simplex virus type 1 (HSV-1) was detected in infected cells with antipeptide sera. The UL1 gene has previously been implicated in virus-induced cell fusion (S. Little and P. A. Schaffer, Virology 112:686-697, 1981). Two protein species, a 30-kDa precursor form and a 40-kDa mature form of the glycoprotein, both of which were modified with N-linked oligosaccharides, were observed. This novel glycoprotein is the 10th HSV-1 glycoprotein to be described and was named glycoprotein L (gL). A complex was formed between gL and gH, a glycoprotein known to be essential for entry of HSV-1 into cells and for virus-induced cell fusion. Previously, it had been reported that gH expressed in the absence of other viral proteins was antigenically abnormal, not processed, and not expressed at the cell surface (U.A. Gompels and A. C. Minson, J. Gen. Virol. 63:4744-4755, 1989; A. J. Forrester, V. Sullivan, A. Simmons, B. A. Blacklaws, G. L. Smith, A. A. Nash, and A. C. Minson, J. Gen. Virol. 72:369-375, 1991). However, gH coexpressed with gL by using vaccinia virus recombinants was antigenically normal, processed normally, and transported to the cell surface. Similarly, gL was dependent on gH for proper posttranslational processing and cell surface expression. These results suggest that it is a hetero-oligomer of gH and gL which is incorporated into virions and transported to the cell surface and which acts during entry of virus into cells.

Amino Acid Sequence↗
PubMed1991

Induction of protective immunity with antibody to herpes simplex virus type 1 glycoprotein H (gH) and analysis of the immune response to gH expressed in recombinant vaccinia virus.

Passive administration of neutralizing monoclonal antibody (MAb) to glycoprotein H (gH) of herpes simplex virus type 1 (HSV-1) was found to protect mice from an HSV-1 strain SC16 challenge infection. To investigate further the protective potential of gH, recombinant vaccinia viruses were constructed which expressed the HSV-1 gH open reading frame under the control of the vaccinia virus 7.5K early/late promoter or the 4b late promoter. Immunization with recombinant viruses, however, did not induce the production of neutralizing antisera and the mice were not protected from zosteriform spread or the establishment of latent infection following viral challenge. The gH produced by the recombinant vaccinia viruses differed in electrophoretic mobility and antigenicity from authentic HSV-1 gH. Only one of three neutralizing MAbs specific for conformational epitopes on gH was able to immunoprecipitate gH synthesized in recombinant vaccinia virus-infected cells. In addition cell surface expression of gH was not detected in cells infected with the recombinant vaccinia viruses.

Animals↗
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↗
PubMed1990

Immunogenicity of herpes simplex virus type 1 glycoproteins expressed in vaccinia virus recombinants.

Vaccinia virus recombinants expressing glycoproteins B (vgB11), D (VgD52), E (gE/7.5 and gE/4B), G (gG-vac), H (gH-vac), and I (gI-vac) of HSV-1 were used to compare the protective response to these individual glycoproteins in the mouse. Glycoprotein D induced the best neutralizing antibody titers and the most increased rates of HSV clearance from the ear as well as good protection from the establishment of latent HSV infections in the sensory ganglia. Glycoprotein B also induced good neutralizing antibody titers and as great a protection from the establishment of latency as gD although the rate of virus clearance from the ear was not as great as after immunization with gD. Glycoprotein E induced weak neutralizing antibody but gG, gH, and gI did not show a neutralizing antibody response. At higher challenge doses of virus (10(6) PFU HSV-1 in the ear), gE induced a protective response by increasing the rate of virus clearance and reducing the acute infection of ganglia as compared to negative control immunized mice. However there was no protection from the establishment of latent infections after immunization with gE. No protective response was seen to gG, gH, or gl.

Animals↗
PubMed1990

Cloning and molecular characterization of the murine herpesvirus 68 genome.

Murine herpesvirus 68 (MHV-68) is a naturally occurring herpesvirus of small free-living rodents. In order to facilitate the molecular characterization of the virus genome, a library of cloned restriction fragments has been produced and restriction enzyme cleavage maps deduced for the enzymes BamHI, EcoRI and HindIII. The MHV-68 genome comprises a region of unique DNA of approximately 118 kbp which is flanked by variable numbers of a 1.23 kb repeat unit. The organization of the MHV-68 genome is, therefore, most similar to that of the lymphotropic gamma 2 group of herpesviruses which include herpesvirus saimiri and herpesvirus ateles.

Animals↗
PubMed1990

Production and characterisation of a monoclonal antibody to human papillomavirus type 16 using recombinant vaccinia virus.

A monoclonal antibody was raised against the major capsid protein L1 of human papillomavirus type 16, using a recombinant vaccinia virus that expresses the L1 protein, as a target for screening. This antibody, designated CAMVIR-1, reacted with a 56 kilodalton protein in cells infected with L1-vaccinia virus, and the protein was present in a predominantly nuclear location. The antibody also detects the HPV-16 L1 antigen in formalin fixed, paraffin wax embedded biopsy specimens and on routine cervical smears. The antibody reacts strongly and consistently with biopsy specimens containing HPV-16 or HPV-33, but very weak reactions were occasionally observed with biopsy specimens or smears containing HPV-6 or HPV-11. The potential advantages of using a vaccinia recombinant are (i) the target protein is synthesised in a eukoryotic cell so that its "processing" and location are normal; (ii) cells infected with vaccinia recombinants can be subjected to various fixing procedures similar to those used for routine clinical material. This greatly increases the probability that an identified antibody will be useful in a clinical setting.

Animals↗
PubMed1989

Properties of a non-tumorigenic human cervical keratinocyte cell line.

A human cervical keratinocyte cell line, W12, has been initiated from a low-grade cervical lesion histologically diagnosed as CIN I. This cell line has, to date, undergone over 300 generations in vitro with an average doubling time of 30 hr: an aneuploid karyotype has developed with progressive in vitro growth. W12 contains HPV16 DNA present at approximately 100 copies and the state of the viral DNA over a number of passages has been examined. The HPV16 DNA is stably maintained at high copy number over several passages and restriction enzyme analysis together with electrophoresis of uncleaved viral DNA indicate that it is present predominantly as the episomal molecule. W12 cells exhibit a typical keratinocyte morphology and, when transplanted into the flank of the nude mouse, form an epithelial lesion with the histological features of CIN I/II.

Adult↗
PubMed1989

The role of herpes simplex virus type 1 thymidine kinase in pathogenesis.

A genetically engineered herpes simplex virus type 1 (HSV-1)thymidine kinase (TK) deletion mutant has been constructed and used to investigate the role of this gene in pathogenesis. Inoculation of mice with the HSV TK deletion mutant resulted in the establishment of latent ganglionic infection as demonstrated by superinfection of explanted ganglia with wild-type (wt) virus but not by routine explant culture suggesting that the virus-encoded TK is not essential for the establishment of latent infection but may be necessary for either reactivation or virus replication following reactivation. In addition, Southern blot hybridization has been used to demonstrate in vivo complementation of this mutant by wt virus in both peripheral and central nervous system tissues of mice during acute infection and to show that such complementation can result in the establishment and reactivation of latent TK- infection.

Acute Disease↗
PubMed1989

Antigenic properties and cellular localization of herpes simplex virus glycoprotein H synthesized in a mammalian cell expression system.

Herpes simplex virus type 1 glycoprotein H (HSV-1 gH) was synthesized in an inducible mammalian cell expression system, and its properties were examined. The gH coding sequence, together with the stable 5' untranslated leader sequence from xenopus beta-globin, was placed under control of the strong promoter from the human cytomegalovirus major immediate-early gene in an amplifiable plasmid which contains the simian virus 40 (SV40) virus origin for replication (ori). This expression vector was transfected into ts COS cells constitutively expressing a temperature-sensitive SV40 T antigen which allows utilization of the SV40 ori at permissive temperatures. The results of transient expression assays at the permissive temperature showed that HSV-1 gH could be synthesized in greater amounts than those produced by a high-multiplicity virus infection. The proteins produced were detected in Western blots (immunoblots) with a HSV-1 gH-specific polyclonal serum raised against a TrpE-gH fusion protein. The transfected gH had an apparent molecular weight of approximately 105,000, intermediate in size to those of the precursor (100,000) and fully processed forms (110,000) of HSV-1 gH from infections. Antigenicity was investigated by reactions with three virus-neutralizing monoclonal antibodies specific for conformational epitopes on gH. Only one of these monoclonal antibodies could immunoprecipitate the synthesized gH. However, equal recognition of the transfected gH was achieved by superinfection with virus. In addition, detectable amounts of gH were not expressed on the cell surface unless the cells were superinfected with virus. Studies with a temperature-sensitive mutant, ts1201, defective in encapsidation showed that the changes in antigenic structure and cell surface expression caused by superinfection with virus were not due simply to incorporation of gH into virions. These results suggest that gH requires additional virus gene products for cell surface localization and formation of an antigenic structure important for its function in mediating infectivity.

Animals↗
PubMed1988

Excretion of non-infectious virus particles lacking glycoprotein H by a temperature-sensitive mutant of herpes simplex virus type 1: evidence that gH is essential for virion infectivity.

A temperature-sensitive mutant of herpes simplex virus type 1, tsQ26, was shown to contain an amino acid substitution in glycoprotein H (gH). The mutant entered cells efficiently at the non-permissive temperature and replicated to give nearly normal yields of intracellular infectivity. The intracellular virions contained, predominantly, an immature form of gH and no gH was found on the surface of infected cells. Excreted virions were devoid of gH and were not infectious. Virions excreted at the permissive temperature were infectious and contained gH and no loss of gH resulted from incubation of these virions at the non-permissive temperature. The temperature-sensitive phenotype apparently results from the loss of gH from virions during their transport to the cell surface, and since loss of gH is accompanied by loss of infectivity we conclude that gH is an essential component of the infectious virion.

Animals↗
PubMed1988

Analysis of the L1 gene product of human papillomavirus type 16 by expression in a vaccinia virus recombinant.

The L1 open reading frame of human papillomavirus type 16 (HPV16) has been expressed in vaccinia virus under the control of both the 7.5K early and late promoter, and the 4b major late promoter. Antibodies to a beta-galactosidase fusion protein containing a C-terminal portion of the HPV16 L1 gene product were used to compare the levels of L1 expression in the two recombinants, and showed that greater levels of expression were obtained when the gene was placed under the control of the 4b late promoter. Immunofluorescence studies revealed a nuclear location of the L1 gene product when expressed in vaccinia virus. Antibodies to the beta-galactosidase fusion protein detected a major polypeptide species of 57K and a minor species of 64K in Western blots of recombinant-infected cell lysates. The 64K species was not detected when cells were infected in the presence of tunicamycin, indicating that the primary translation product of the HPV16 L1 open reading frame is modified by N-linked glycosylation when expressed in vaccinia virus. Whereas antibodies to HPV16 L1 fusion proteins and to a peptide containing amino acids from the C terminus of HPV16 L1 reacted well in Western blots with the HPV16 L1 target expressed in vaccinia virus, no reactivity was observed with antibodies to bovine papillomavirus type 1 particles or to a HPV6b fusion protein.

Animals↗
PubMed1988

Antigenic analysis of a major neutralization site of herpes simplex virus glycoprotein D, using deletion mutants and monoclonal antibody-resistant mutants.

Herpes simplex virus glycoprotein D is a component of the virion envelope and appears to be involved in attachment, penetration, and cell fusion. Monoclonal antibodies against this protein can be arranged in groups on the basis of a number of biological and biochemical properties. Group I antibodies are type common, have high complement-independent neutralization titers, and recognize discontinuous (conformational) epitopes; they are currently being used in several laboratories to study the functions of glycoprotein D. We have used a panel of neutralization-resistant mutants to examine the relationships between these antibodies in detail. We found that they can be divided into two subgroups, Ia and Ib, such that mutations selected with Ia antibodies have little or no effect on binding and neutralization by Ib antibodies and vice versa. In addition, Ia antibodies are able to bind deletion and truncation mutants of glycoprotein D that Ib antibodies do not recognize, suggesting that their epitopes are physically distinct. However, with one exception, Ia and Ib antibodies block each other strongly in binding assays with purified glycoprotein D, whereas antibodies from other groups have no effect. We have therefore defined the sum of the Ia and Ib epitopes as antigenic site 1.

Antibodies, Monoclonal↗
PubMed1986

Identification of the human cytomegalovirus glycoprotein B gene and induction of neutralizing antibodies via its expression in recombinant vaccinia virus.

A human cytomegalovirus (HCMV) glycoprotein gene with homology to glycoprotein B (gB) of herpes simplex virus and Epstein-Barr virus and gpII of varicella zoster virus has been identified by nucleotide sequencing. The gene has been expressed in recombinant vaccinia virus and the gene product recognized by monoclonal antibodies and human immune sera. Rabbits immunized with the recombinant vaccinia virus produced antibodies that immunoprecipitate gB from HCMV-infected cells and neutralize HCMV infectivity in vitro. These data demonstrate a role for this protein in future HCMV vaccines.

Amino Acid Sequence↗
PubMed1986

The herpes simplex virus type 2 equivalent of the herpes simplex virus type 1 US7 gene and its flanking sequences.

Nucleotide sequencing studies (D. J. McGeoch, A. Dolan, S. Donald, and F. Rixon, 1985, J. Mol. Biol. 181, 1-14) have indicated that herpes simplex virus type 1 (HSV-1) has a coding sequence, referred to as US7, between the genes for the glycoproteins D and E (gD and gE). Northern blot analysis and nucleotide sequencing have been carried out to show that the type 2 virus (HSV-2) has an equivalent to the US7 gene. A comparison with the HSV-1 sequence has revealed some surprising similarities and differences. At the nucleotide level, HSV-2 has inserted a large sequence into the gE promoter, retained a large palindrome present in the coding sequence but not some tandem repeats, and deleted a region beside those repeats. At the amino acid level, the putative transmembrane sequence has been remarkably well conserved, and hydrophobic moment analysis indicates that it could be interacting with polar species within the plane of the membrane. Immediately after the deletion in the HSV-2 sequence, there is an N-glycosylation signal, and HSV-2 has one more such signal than HSV-1. The longest conserved sequence at the nucleotide level codes for a region of polypeptide that is strongly predicted to fold into alpha-helix. Implications of these analyses to the structure and possible function of these molecules are discussed.

Amino Acid Sequence↗
PubMed1986

An analysis of the biological properties of monoclonal antibodies against glycoprotein D of herpes simplex virus and identification of amino acid substitutions that confer resistance to neutralization.

Four monoclonal antibodies to glycoprotein D (gD) of herpes simplex virus (HSV) types 1 and 2 neutralized virus in the presence of complement but exhibited diverse activities in its absence. Amino acid substitutions that conferred resistance to neutralization by each antibody were identified by deriving the nucleotide sequence of the gD gene from resistant mutants. Each antibody selected a substitution from different parts of the molecule and mutants resistant to a single antibody always arose from the same mutation. One of the antibodies reacted with a synthetic oligopeptide corresponding to the region of the molecule in which amino acid substitution conferred resistance, but the remaining three antibodies failed to react with predicted oligopeptide targets. These antibodies may therefore react with 'discontinuous' epitopes, a view supported by the observation that two of these three antibodies competed with each other in binding assays despite the fact that substitutions conferring resistance to neutralization arose nearly 100 residues apart in the primary sequence. The four antibodies had very different biological properties. One antibody neutralized infectivity but did not inhibit cell fusion, one antibody inhibited cell fusion but did not neutralize, while a third antibody had both activities. One antibody had neither activity but enhanced the infectivity of HSV-2 in a type-specific manner. The ability of antibodies to inhibit cell fusion by syncytial virus strains correlated with an ability to prevent plaque enlargement by a non-syncytial virus strain, implying a role for gD in the intercellular spread of virus that is independent of the syncytial phenotype. We found no correlation between neutralizing activity and anti-fusion activity suggesting that, while gD is involved in cell fusion, it has at least one other function which is required for infectivity.

Amino Acid Sequence↗