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Biomedical subjects

E A Gould

Publications and source records attributed to E A Gould.

13 recordsLinked to original sources
PubMed1992

Heterologous resistance to superinfection by louping ill virus persistently infected cell cultures.

Louping ill virus, a tick-borne arbovirus readily established a persistent infection in porcine kidney (PS) cells after initially inducing minor cytopathic changes. Nucleotide sequence analysis of the envelope glycoprotein of the viral RNA recovered from the persistently infected cells showed no changes as compared with the virus used to establish persistent infections. More than 80 per cent of the cells contained virus specific antigen when analysed by indirect immunofluorescence microscopy. This persistently infected cell line resisted superinfection with either homologous or most heterologous flaviviruses. However, the yellow fever French neurotropic virus (YF FNV) multiplied in the persistently infected cells and evidence of dual infections in these cells was obtained using specific monoclonal antibodies in double labelling immunofluorescence tests. The relevance of these observations is discussed in the light of other evidence that tick-borne viruses can survive for long periods in wild animal species.

Animals↗
PubMed1992

Nucleotide sequence of the envelope glycoprotein of Negishi virus shows very close homology to louping ill virus.

Negishi virus, a member of the family Flaviviridae, was originally isolated in Japan, during an outbreak of Japanese encephalitis. Antigenically, however, Negishi virus resembles the tick-borne rather than the mosquito-borne flaviviruses. Monoclonal antibodies that bind louping ill virus showed a close antigenic relationship between louping ill and Negishi virus. The genes encoding the envelope glycoprotein of Negishi virus (strain 3248/49/P10) and louping ill virus (strain SB526) were cloned and sequenced. They showed a very close homology at both the nucleotide and deduced amino acid levels. Comparison with the known sequence of another strain of louping ill virus (strain 369/T2) and with other tick-borne flaviviruses showed that Negishi virus was more closely related to louping ill virus than to the other tick-borne viruses. The significance of this observation for virus evolution, virus distribution in the environment, and the potential use of nucleotide sequencing for rapid and precise identification of flaviviruses are discussed.

Amino Acid Sequence↗
PubMed1992

Louping ill virus envelope protein expressed by recombinant baculovirus and vaccinia virus fails to stimulate protective immunity.

We have constructed recombinant baculoviruses and vaccinia viruses containing cloned DNA, encoding either the envelope protein alone or all of the structural proteins (core, membrane and envelope) of louping ill virus. Glycosylated viral envelope protein, presented both inside and on the surface of insect and mammalian cells, was expressed by all four recombinant viruses. Differences in antigenic presentation of the envelope protein were observed between the envelope protein and structural protein constructs as well as between the insect and mammalian cell expression systems. Despite the expression of epitopes known to elicit neutralizing and protective antibodies when present in authentic antigen, the recombinant envelope protein expressed by either vector failed to induce, in mice or rabbits, either neutralizing or protective antibodies against louping ill virus.

Amino Acid Sequence↗
PubMed1992

Envelope protein sequences of dengue virus isolates TH-36 and TH-Sman, and identification of a type-specific genetic marker for dengue and tick-borne flaviviruses.

Complementary DNAs were synthesized from the envelope protein genes of two isolates of dengue virus (TH-36 and TH-Sman, previously suggested as possible dengue virus type 5 and dengue virus type 6 respectively) and amplified by the polymerase chain reaction using sense and antisense primers designed from conserved dengue virus gene sequences. The amplified cDNA clones were sequenced in both directions by double-stranded dideoxynucleotide sequencing. Alignment with published dengue virus sequences enabled us to assign these viruses accurately to classified serotypes, confirming that TH-36 and TH-Sman are strains of dengue virus type 2 and dengue virus type 1 respectively. Amino acid changes between the proteins encoded by these two isolates and strains of their respective serotypes may account for the significant antigenic differences observed during previous serological typing of these viruses. Moreover, sequence alignment of flavivirus envelope proteins revealed a hypervariable region, within which members of the dengue and tick-borne virus antigenic complexes show unique peptide sequences. This type-specific hypervariable domain may be useful as a genetic marker for typing dengue and tick-borne flaviviruses.

Amino Acid Sequence↗
PubMed1979

Factors affecting the growth and titration by immunofluorescence of simian foamy virus.

This paper presents some observations concerned with the growth of simian foamy virus and some modifications which should be introduced to the fluorescence assay of foamy virus. The modified procedure is the most sensitive method described for the titration of foamy virus. Examination of the optimal conditions for the growth and titration by fluorescence assay of simian foamy virus showed that the virus was particularly sensitive to changes in virus and cell concentration. At the low cell concentrations employed previously a "saturation-type" response was obtained with high titre virus and virus adsorption efficiency was decreased as input virus was diluted. Maximum virus production was obtained with high cell concentrations at input multiplicities of 5 and 10. At high multiplicities of infection more than 90 per cent of the cells adsorbed virus but only 45 per cent became infected, this appeared to be related to cell DNA synthesis.

Adsorption↗
PubMed1979

A comparison of polypeptides in measles and SSPE virus strains.

The polypeptide patterns of twelve subacute sclerosing panencephalitis (SSPE) and measles viruses have been compared by slab gel electrophoresis. The polypeptide patterns of nine strains of SSPE and measles virus were identical. Differences in the NP protein and the HA protein of the Oddo strain, the P protein of the large plaque variant of the Lec strain of SSPE and in the M protein of the Hu 2 measles strain could not be correlated with biological characteristics such as plaque morphology, origin or haemagglutination properties.

Electrophoresis, Polyacrylamide Gel↗
PubMed1979

Comparison of the antigens produced by foamy virus in a cytolytic and a persistent infection of HEp2 cells.

The antigens from cytolytic infections of HEp2 cells by type I simian foamy virus produced two multicomponent precipitation lines when tested by immunodiffusion with the homologous hyperimmune rabbit antiserum. The antigens obtained from a non-productive infection of MK5 virus in HEp2 cells produced only those precipitation lines which corresponded with the inner lines obtained from the cytolytic infection. Similarly, hyperimmune rabbit antiserum against antigens extracted from the persistent infection lacked the antibody which was responsible for the outer lines of precipitation. Indirect immunofluorescence with acetone-fixed and unfixed cells using the homologous and heterologous sera confirmed the absence of antigens in the persistent infection and showed that an antigen is produced in the persistently infected cells which is either absent or present in very small amounts in cytolytically infected cells. Neutralization experiments and ether treatment suggested that the missing antigens in the persistent infection were the envelope components of foamy virus. It is proposed that the persistent infection has properties in common with some infections by RNA tumour viruses.

Antigens, Viral↗
PubMed1978

Detection of antibody to bovine syncytial virus and respiratory syncytial virus in bovine fetal serum.

Batches of commercial fetal bovine serum, described by the suppliers as antibody-free, all contained antibody to bovine syncytial virus (BSV) when tested by indirect immunofluorescence. Antibody to bovine respiratory syncytial virus (RSV) was not detected in these sera. Twenty-four percent of individual fetal bovine sera contained antibody to BSV, and 14% contained antibody to RSV when tested by indirect immunofluorescence. BSV antibody titers in fetal sera from dams with high BSV antibody levels were variable but always higher than RSV antibody titers. Radial immunodiffusion studies with BSV-positive sera revealed the presence of immunoglobulin M (IgM), IgG, and IgA, but the quantity of these immunoglobulins was not directly related to the BSV antibody titers. The evidence suggests that the antibody present in fetal sera arose as the result of infection rather than from maternal transfer across the placenta.

Animals↗
PubMed1976

Some characteristics of salt-dependent haemagglutinating measles viruses.

Several strains of measles virus which did not agglutinate monkey erythrocytes in phosphate-buffered saline did so in buffer containing 0-8 M-ammonium sulphate. Haemadsorption to cells infected with these viruses was also salt-dependent. In a series of tests salt-dependent agglutinin was shown to be a stable structural component of the infectious virion. The relevance of these findings is discussed in the light of previous reports that many measles virus preparations do not agglutinate erythrocytes.

Ammonium Sulfate↗
PubMed1976

Salt-dependent haemagglutinating measles virus in S.S.P.E.

Two strains fo S.S.P.E. virus show both haemagglutinin and salt-dependent haemagglutinin. These properties are associated with distinct plaque forms within each strain. The existence of salt-dependent strains in wild-type measles virus suggests that they should be found in the early isolates of all strains of S.S.P.E.

Cell Line↗
PubMed1975

The production of a temperature-sensitive persistent measles virus infection.

A persistent infection of measles virus was established in HEp2 cells. All cells contained virus antigen when tested by specific immunofluorescence and approx. 50% were positive by haemadsorption. Infectious virus released into the supernatant medium was usually equivalent to no more than 0-001 p.f.u./cell, but between 10 and 40% of the infected cells produced plaques when plated on Vero cells. Passage of persistently infected cultures in the presence of measles antibody had no effect on the proportion of antigen-positive cells. Virus obtained from the supernatant medium of persistently infected cultures was temperature sensitive at 39-5 degrees C when tested on Vero cells whereas the original non-persistent virus produced infections on Vero cells at 39-8 degrees C. On passage of the persistently infected culture at 39-5 degrees C most of the surface antigens disappeared within 24 h whereas the intracellular virus antigens had not totally disappeared until the 5th passage.

Antigens, Viral↗
PubMed1975

Virus susceptibility of mouse hemopoietic cells in vitro: inhibition of granulocyte-macrophage precursor cells by Newcastle disease virus.

Normal mouse bone marrow cells were exposed to encephalomyocarditis virus (EMC), reovirus type 3 (REO3), influenza virus (FLU), and Newcastle disease virus (NDV) then assayed for granulocyte-macrophage precursor cells by the technique of colony formation in agar. Exposure to EMC, REO3, and FLU caused a slight but variable loss of colony-forming potential, whereas exposure to NDV caused a very marked loss. NDV acted directly on the cells, not indirectly through release of colony-inhibiting factors or destruction of colony-stimulating factor. Experiments with NDV inactivated by heat, ether, or ultraviolet irradiation indicated that colony inhibition was associated with fully infective virus, even though some of the inactivated preparations had retained full hemagglutinin, neuraminidase, or hemolytic activity.

Animals↗