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Biomedical subjects

C J Birch

Publications and source records attributed to C J Birch.

At least 19 recordsLinked to original sources
PubMed1999

Individuals from North America, Australasia, and Africa are infected with four different genotypes of human herpesvirus 8.

To study human herpesvirus 8 (HHV-8) transmission between individuals and in populations, we developed a system for genetic fingerprinting of HHV-8 strains based on variation in the HHV-8 K1, glycoprotein B (gB), and glycoprotein H (gH) genes. Using this system, we sequenced nearly the entire K1 gene (840 bp); two segments of the gB gene (open reading frame 8), totaling 813 bp; and a 702-bp segment of the gH gene (open reading frame 22) from blood and tissue samples obtained from 40 human immunodeficiency virus-infected and noninfected individuals, including those with Kaposi's sarcoma, primary effusion lymphoma, or Castleman's disease. The specimen collection was assembled from individuals living in diverse geographical locations, including the United States, Australia, New Zealand, Uganda, and Zambia. As reported by others, K1 was the most variable gene, with up to 16% variation at the nucleotide sequence level and up to 32% variation at the amino acid sequence level. Despite this extensive sequence variation, the K1 amino acid sequence contained 14 conserved cysteine sites, suggesting a conserved tertiary structure. gB and gH sequences were highly conserved, in most cases differing by <0.6% in pairwise comparisons. K1 was the most useful gene for strain discrimination, but the other genes enabled the discrimination of strains with identical K1 sequences. Individuals from diverse geographic locations were infected with four different HHV-8 genotypes; strains did not strictly segregate by continent of origin. The majority of HHV-8 strains from the United States and Europe were relatively closely related, whereas some strains identified from Uganda and Australia were phylogenetically distant. Genotype I strains were the most common and were found on three continents. Identical sequences were found in specimens obtained from different body sites and at different times from the same individual.

AIDS-Related Opportunistic Infections↗
PubMed1999

Inactivation of feline calicivirus, a Norwalk virus surrogate.

Norwalk and Norwalk virus-like particles (NVLPs) [also known as small round structured viruses (SRSVs)] are members of the family Caliciviridae and are important causes of gastroenteritis in humans. Little is known about their survival in the environment or the disinfection procedures necessary to remove them from contaminated settings. As NVLPs cannot be grown in tissue culture, survival studies require the use of a closely related cultivable virus. This study assesses the survival of the surrogate feline calicivirus (FCV) after exposure to commercially available disinfectants and a range of environmental conditions. Disinfectants tested included glutaraldehyde, iodine, hypochlorite, a quaternary ammonium-based product, an anionic detergent and ethanol. Complete inactivation of FCV required exposure to 1000 ppm freshly reconstituted granular hypochlorite, or 5000 ppm pre-reconstituted hypochlorite solution. Glutaraldehyde and the iodine-based product effectively inactivated FCV whereas the quaternary ammonium product, detergent and ethanol failed to completely inactivate the virus. The stability of FCV in suspension and in a dried state was assessed after exposure to 4 degrees C, room temperature (20 degrees C) and 37 degrees C. With increasing temperature, the stability of FCV was found to diminish both in suspension and in the dried state. FCV in the dried state did not survive for one day at 37 degrees C. This study provides a basis for establishing guidelines for disinfection protocols to decrease the spread of NVLPs in a community setting.

Animals↗
PubMed1997

Transmission of human and feline immunodeficiency viruses via reused suture material.

Several documented cases of human immunodeficiency virus (HIV) infection have involved unconventional or unknown modes of transmission of the virus. Some such cases have occurred within a surgical setting. We investigated the potential for transmission of HIV on suture material that had been reused following passage through an HIV-infected patient. Initial experiments were conducted in vitro using HIV. To provide stronger evidence that HIV could be transmitted via this route, further experiments were undertaken in vivo using a feline immunodeficiency virus (FIV)/cat model. Both methods indicated the possibility of transmission of virus if suture materials were reused.

Animals↗
PubMed1996

Syncytium-inducing phenotype and zidovudine susceptibility of HIV-1 isolated from post-mortem tissue.

OBJECTIVE: To establish the syncytium-inducing (SI) phenotype and zidovudine (ZDV) susceptibility of HIV-1 isolates obtained from autopsy specimens. METHODS: Isolation of HIV was attempted from autopsy specimens obtained from 76 AIDS patients. Specimens of lymph node, spleen, spinal cord, brain and cerebrospinal fluid (CSF) were processed and cultured with peripheral blood mononuclear cells (PBMC) from seronegative donors. Biological phenotype was determined in a T-lymphocyte line (MT-2). ZDV susceptibility was evaluated in a PBMC-based assay. Sequencing of amino-acid codons in the reverse transcriptase gene previously shown to be associated with ZDV resistance was carried out on a subgroup of isolates. RESULTS: HIV was recovered from tissue specimens and CSF up to 5 days post-mortem, but recovery rate of infectious virus decreased as the time between autopsy and specimen processing increased. There was a lack of concordance between PBMC isolates and isolates from different tissue sites with respect to SI phenotype. ZDV-resistant virus was isolated from post-mortem specimens of patients who had received long-term ZDV therapy up until or shortly before their death. ZDV-sensitive virus re-emerged in the lymph node of patients who ceased treatment several months prior to death. Phenotypically sensitive virus obtained from lymph node tissue of three patients after a relatively short time off ZDV (4-6 months) retained some of the amino-acid substitutions known to be associated with resistance. CONCLUSION: The data suggests that ZDV resistance and re-emergence of sensitive virus does not originate in peripheral cells, and that these cells and tissues are seeded with virus present elsewhere, possibly in the germinal centres of the lymph node.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Isolation of HIV-1 from experimentally contaminated multidose local anaesthetic vials.

OBJECTIVE: To investigate the hypothesis that HIV can be transmitted via contamination of multidose vials of local anaesthetic solution through reuse of needles and syringes. DESIGN AND SETTING: Laboratory study. (1) By experiments with multidose vials and disposable needles and syringes, we identified a sequence of events in which HIV could contaminate the anaesthetic solution. (2) Three anaesthetic solutions were contaminated with a laboratory strain of HIV and tested by viral culture and p24 enzyme immunoassay one, two and four hours later to see how long the virus remained active. RESULTS: (1) Needles and syringes retained small volumes of fluid after use (mean, 25 microL; in syringe alone, mean 16 microL) which could be transferred to multidose vials of local anaesthetic. (2) 10 mL of anaesthetic solution contaminated with 8 microL of HIV-infected solution (equivalent to 1% infected lymphocytes in vivo) contained active virus one hour later. In some settings, HIV could be isolated four hours after exposure. CONCLUSION: When inadvertently contaminated with HIV, multidose solutions represent a potential source of transmissible virus.

Anesthetics, Local↗
PubMed1995

Susceptibility of HIV to inactivation by disinfectants and ultraviolet light.

Assays were developed to assess a variety of conditions and presentations of infectious HIV to potential inactivating sources. A range of commercially available disinfectants with active constituents including glutaraldehyde, chlorine, phenolics, alcohol, iodine and quaternary ammonium compounds was tested. In addition, u.v. light was investigated as a potential inactivating source. All products were assessed against cell-free HIV in culture medium and cell-associated HIV suspended in medium or whole human blood. All products completely inactivated cell-free HIV following a 1 min exposure. However, cell-associated HIV was more resilient, requiring exposure of 5 min or more for some disinfectants. The effectiveness of the disinfectants was further compromised in the presence of blood.

Blood↗
PubMed1994

The use of a scanning proton microprobe to observe anti-HIV drugs within cells.

A series of inorganic polyanions (viz. heteropolytungstates) has been shown to have antiviral activity but there was no evidence to indicate that the drugs reached their site of antiviral (HIV) activity intact. We have shown that with a scanning proton microprobe it is possible to analyse the metal content of individual cells (PBLs) treated with such a polyoxometalate drug and to determine the atomic ratio of the metals within the cell. This was found to be near that in the drug. The distribution of the metals (tungsten and cobalt) within the cell was measured and it was shown that both metals were located in the same region within the cell. These findings would suggest that the drug had entered the cells intact.

Antiviral Agents↗
PubMed1992

Clinical effects and in vitro studies of trifluorothymidine combined with interferon-alpha for treatment of drug-resistant and -sensitive herpes simplex virus infections.

Three AIDS patients with severe cutaneous herpes simplex virus (HSV) infection refractory to therapy with acyclovir and foscarnet (2 patients) were treated with a topical preparation of trifluorothymidine (TFT) and interferon-alpha. Complete healing of lesions occurred in 1 patient; a second had significant regression of the infected area. In the third, the lesion was stabilized twice after application of the preparation and reduced in size after a subsequent treatment. In vitro studies confirmed that isolates from these patients were acyclovir- or acyclovir/foscarnet-resistant. In addition, they revealed strong synergy between TFT and interferon-alpha for these isolates and for strains with wild-type drug sensitivity profiles. Topical TFT/interferon-alpha may be of benefit in the therapy of mucocutaneous HSV infections, especially when they are resistant to treatment with systemic antiviral agents.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Altered sensitivity to antiviral drugs of herpes simplex virus isolates from a patient with the acquired immunodeficiency syndrome.

Acyclovir (ACV)-resistant herpes simplex virus type 2 (HSV-2) was isolated from a patient with acquired immunodeficiency syndrome after long-term but intermittent ACV therapy. These thymidine kinase-defective isolates were sensitive in vitro to foscarnet. While combined therapy with ACV and interferon produced only partial clinical improvement, the in vitro effect of this combination against an ACV-resistant isolate from the patient was strongly synergistic. A short course (10-12 days) of intravenous foscarnet controlled severe ulceration, and clinical improvement lasted 6 months. After recurrence and further courses of foscarnet, however, the patient responded poorly, and subsequent HSV isolates were resistant to both ACV and foscarnet and hypersensitive to aphidicolin.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Feline immunodeficiency virus: prevalence, disease associations and isolation.

Of 467 cat serums tested for antibody to feline immunodeficiency virus (FIV) 120 (26%) were positive. The average age of positive cats was 7.5 years (range 1 to 16 years), and 67% were male. Of 110 serums collected in 1980, 27 (24.5%) were positive. A wide variety of clinical signs including oral cavity disease, anorexia, weight loss, lethargy, depression, fever, respiratory and urinary tract disease, conjunctivitis, abscesses, anaemia and lymphadenopathy were observed in the cats with serum antibody. There was often a history of chronic disease or recurrence of particular or various clinical signs in these cats. FIV was isolated from 4 of 8 FIV antibody positive cats by cocultivation of patient lymphocytes with donor lymphocytes in the presence of interleukin 2.

Animals↗
PubMed1988

Use of serotype-specific monoclonal antibodies to study the epidemiology of rotavirus infection.

The development of an enzyme immunoassay (EIA) capable of serotyping human rotavirus (HRV) in faecal extracts has enabled us to retrospectively study the epidemiology of rotavirus infection in Melbourne. Of 552 stored specimens obtained from individuals with rotavirus-associated gastroenteritis between 1975 and 1986, the serotype could be determined in 62%. Infection was most prevalent in two groups, neonates and children aged between 12 and 24 months. In these groups infection was due to different serotypes, type 1 in older children and an untypable virus in infants. Serotype 1 strains were detected in greater numbers than the other serotypes and circulated in each year of the study. Serotype 2 rotaviruses were associated with a large epidemic in 1978, but have been detected only rarely since.

Age Factors↗
PubMed1988

Synthesis of human rotavirus polypeptides in cell culture.

The replication strategy of a human serotype 1 rotavirus, adapted to rapid growth in CV-1 cells, was investigated. A single cycle growth curve revealed eclipse and latent periods of 3 and 4 hours, respectively. Although the extent of reduction of host cell protein synthesis was directly related to the multiplicity of infection of the virus, incorporation of actinomycin D and excess NaCl into the medium resulted in significant reduction in host cell background and enabled observation of viral polypeptides as early as 2 hours post infection. Five polypeptides were found to be structural components of the virion, and a further eight appeared to be nonstructural proteins or intermediates. Five polypeptides were glycosylated during virus replication, but only one of these, VP7, was a definite structural glycoprotein. Pulse-chase experiments revealed that four low molecular weight polypeptides underwent post-translational modifications.

Animals↗
PubMed1985

Isolation of feline rotaviruses and their relationship to human and simian isolates by electropherotype and serotype.

Rotaviruses were detected by electron microscopy in the faecal specimens of six clinically well cats and virus was subsequently isolated from four of them. Analysis of the RNA of the isolates showed the existence of three electrophoretic types characteristic of the 'long' RNA electrophoretic pattern exhibited by rotaviruses. All feline isolates were neutralized only by antiserum to SA11 rotavirus, indicating that these isolates were serotype 3 rotaviruses. Antiserum prepared against a feline strain neutralized all the feline isolates as well as SA11 but showed no neutralizing activity against human isolates of serotype 1, 2 or 4.

Animals↗
PubMed1984

Influenza in Melbourne, 1982. Epidemiology and virology.

The major features of the outbreaks of influenza A and B, which occurred in Melbourne during the winter of 1982, are described. Diagnoses of influenza A or influenza B were established in 310 patients by virus isolation, immunofluorescence, and serological tests. Immunofluorescence was found to be a valuable, rapid, but considerably less sensitive, test than virus isolation, and serodiagnosis was the test of choice either when patients did not present or when specimens were not collected until late in the illness. The results of haemagglutination-inhibition tests performed with a panel of monoclonal antibodies suggest that at least two recognizably different strains of influenza A and influenza B were circulating in the community.

Adolescent↗
PubMed1983

Replication of human rotavirus in cell culture.

Nine strains of human rotavirus were adapted to growth in CV-1 and/or MA-104 cells following pretreatment of virus with trypsin, incorporation of trypsin into culture medium, and use of roller cultures. Immunofluorescence was the most reliable method for the detection of virus replication, although characteristic cytopathic effects were produced sporadically by most isolates. Virus could be readily detected in supernatant fluids of cell cultures and in cell sections by electron microscopy.

Animals↗
PubMed1982

Human rotavirus infection in Efate, Vanuatu.

Serum and fecal samples collected from children with gastroenteritis and healthy children and adults living in Efate, Vanuatu (formerly the New Hebrides), were tested for the presence of human rotavirus antigen or antibody by electron microscopy and enzyme-linked immunosorbent assay. Virtually every subject was found to have detectable levels of antibody and age-specific studies showed that primary infections occur early in life. Human rotavirus was demonstrated to be the cause of an outbreak of gastroenteritis among children which occurred between August and September 1980, although it had not been detected in the population in the preceding 13 months. Epidemics of human rotavirus-associated gastroenteritis appear to occur every 2nd year in this population.

Adolescent↗