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Biomedical subjects

J V Parry

Publications and source records attributed to J V Parry.

At least 127 records · Page 7Linked to original sources
PubMed1988

Diagnostic value of specific IgM antibodies in primary HIV infection.

Sequential serum samples from 55 homosexual men with primary HIV infection were tested for IgM anti-HIV. An early IgM response was found in 27 out of 55 (49%). In five cases IgM anti-HIV was detected 1-3 1/4 months prior to IgG anti-HIV seroconversion, as detected by a commercially available ELISA, but in no case was IgM detected prior to IgG anti-HIV seroconversion, as detected by the more sensitive GACRIA (IgG antibody captive radio-immunoassay, see Subjects and methods) and immunoblot assays. In 22 out of 23 men (96%) the primary IgM response did not persist beyond 3 months. HIV antigenaemia was found before HIV antibody seroconversion in 6 out of 55 (11%) and concomitant with HIV antibody seroconversion in 8 out of 55 (15%) subjects. A 'flu-like' illness that might be ascribed to primary HIV infection was found in 37 out of 50 men (74%). A blood sample was taken from 11 men during or within 2 weeks of the illness: no serological markers of HIV infection were detected in four subjects, HIV antigen, IgM and IgG anti-HIV were detected in another four, HIV antigen was the only marker of HIV infection in two subjects, and in one subject, IgM and IgG anti-HIV were detected but not HIV antigen. These results indicate that no conclusive value can be attached to a negative IgM test in suspected primary HIV infection, and that any role for IgM anti-HIV testing in blood donor screening is highly questionable.

Acquired Immunodeficiency Syndrome↗
PubMed1988

HIV surveillance by testing saliva.

Saliva specimens were tested for HIV antibody (anti-HIV) by an immunoglobulin G (IgG) antibody capture radioimmunoassay (GACRIA) and three sensitive commercial assays. In tests on 460 seronegative subjects and 196 seropositive subjects GACRIA was 99.8% specific and 100% sensitive. The Wellcome HIV monoclonal and Abbott recombinant DNA enzyme-linked immunosorbent assays (ELISAs) were also highly specific (99.8%, 100%) but they were less sensitive (90.9%, 82.0%). The Fujirebio particle agglutination assay was sensitive (97.8%) but its specificity was poor (84.1%). In testing saliva specimens from populations with an anti-HIV prevalence greater than 0.5%, sampling by GACRIA alone could provide a good estimate of the true prevalence. For true prevalences less than 0.5% good estimates could only be obtained if positive GACRIA reactions were confirmed by another independent salivary assay. Salivary testing for anti HIV is a convenient and potentially an accurate epidemiological tool.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Sensitive assays for viral antibodies in saliva: an alternative to tests on serum.

Paired serum and saliva specimens were tested by conventional assays and by IgG-capture radioimmunoassays (GACRIA) and enzyme-linked immunosorbent assays (GACELISA) for antibody to hepatitis A virus (HAV, 100 pairs), human immunodeficiency virus (HIV, 53), hepatitis B virus core (HBc, 62), and rubella virus (30). Conventional assays failed to detect viral antibodies in the saliva of 93 of 119 seropositive subjects. However, GACRIA detected the antibodies in both serum and saliva of all subjects seropositive by conventional tests, except 2 saliva specimens false-negative for anti-HBc and 1 false-negative for anti-rubella-virus. For anti-HIV and anti-HBc serum and saliva GACRIA reactivities did not differ significantly, but anti-HAV and anti-rubella-virus GACRIA reactivities were stronger in serum than saliva. GACRIA and GACELISA results on saliva for the four antibodies correlated closely; for anti-HAV and anti-HIV GACELISA and GACRIA were equally accurate. For both saliva and serum, GACRIA was superior to an IgA-capture assay in detecting anti-HAV and anti-HIV.

Antibodies, Viral↗
PubMed1987

Studies on heat inactivation of hepatitis A virus with special reference to shellfish. Part 1. Procedures for infection and recovery of virus from laboratory-maintained cockles.

The consumption of bi-valve molluscan shellfish has been associated with outbreaks of viral gastroenteritis and hepatitis A. Investigations were undertaken to determine the heat inactivation conditions necessary to render shellfish such as cockles safe for the consumer. Conditions for the laboratory maintenance of live cockles are described. In preliminary experiments either poliovirus (10(6) TCID50/ml seawater) or hepatitis A virus (HAV) (approx. 10(4) RFU/ml seawater) was introduced into the shellfish tank. Following 48 h filter feeding, virus was recovered from cockles using an adsorption-elution extraction procedure. Titres of virus recovered ranged from 10(4) to 10(5) TCID50/ml of shellfish extract for poliovirus and from 10(3) to 10(5) RFU/ml of shellfish extract for HAV. Active ingestion of the virus from the seawater was demonstrated by recovering virus from within cockle guts. To quantify recovered HAV, end-point dilutions and an adaptation of a radioimmunofocus assay (RIFA) were compared. The tests were of similar sensitivity but the RIFA has the advantage of being relatively rapid, shortening the time taken to complete an experiment by as much as 4 weeks.

Animals↗
PubMed1986

An immunoglobulin G capture assay (GACRIA) for anti-HTLV III/LAV and its use as a confirmatory test.

An immunoglobulin G (IgG) antibody capture assay (GACRIA) methodologically distinct from other assays for the detection of antibodies to human T-lymphotropic virus type III/lymphadenopathy-associated virus (anti-HTLV III/LAV) was developed and used to test 1,055 serum samples previously screened by a competitive assay (COMPRIA). Eight hundred and twenty-three (78%) sera were positive and 129 (12.2%) negative in both assays. The coefficient of correlation between the two assays was 0.87, and COMPRIA appeared more sensitive than GACRIA. On retesting 103 sera that gave initially conflicting results, 81 discrepancies were resolved, 77 because of a change in the COMPRIA result. The 22 persistently discrepant samples gave an equivocal or positive result by COMPRIA and were negative by GACRIA. Thirteen of these 22 were positive in a commercial ELISA (ELAVIA). Twenty of them were also tested by Western blot; all were reactive with at least two HTLV III/LAV protein bands. The persistently discrepant samples were of four types: laboratory control sera (n = 2); naturally occurring weakly reactive samples (n = 5); samples that were anti-HTLV III/LAV IgG negative but IgM positive (n = 5; all five individuals from whom these samples were drawn were symptomatic); samples from one laboratory that were probably accidentally contaminated with anti-HTLV III/LAV-positive serum (n = 10). It was concluded that GACRIA for anti-HTLV III/LAV is specific and adequately sensitive and, in conjunction with other assays, is a useful confirmatory test whose format could readily be changed to ELISA.

Antibodies, Viral↗
PubMed1986

Human exposure to bovine polyomavirus: a zoonosis?

A competitive-type solid phase radioimmunoassay (RIA) was developed for the detection of antibody to bovine polyomavirus. Comparison of RIA and counter-immunoelectrophoresis (CIE) results on 273 cattle sera indicated that both techniques were detecting antibody of like specificity. Human sera from 256 blood donors, 219 people recently vaccinated against polio, rubella or rabies, 50 immunosuppressed patients and 472 people with various occupational exposure to cattle were tested for antibody to bovine polyomavirus, the foetal rhesus monkey kidney strain, (anti-FRKV) by RIA. Apart from one blood donor and one of 108 rabies vaccinees only those in close contact with cattle possessed anti-FRKV. Compared with 62 per cent seropositive in the natural hosts, cattle, 71 per cent of veterinary surgeons, 50 per cent of cattle farmers, 40 per cent of abattoir workers, 16 per cent of veterinary institute technical staff and 10 per cent of veterinary students were anti-FRKV positive. Our findings indicate that the theoretical hazard of FRKV infection from undetected contamination of current tissue culture derived vaccines may, in practice, be remote. Proposed wider use of primate kidney cells as substrates for new vaccines may increase this risk.

Animals↗
PubMed1985

Which anti-HTLV III/LAV assays for screening and confirmatory testing?

In preparation for routine anti-HTLV-III/LAV testing in the UK five commercial assays (A-E) were evaluated using 360 sera selected on clinical and epidemiological grounds. These comprised 220 specimens from blood donors, 83 specimens from patients in high-risk groups, and 57 specimens with features likely to produce false-positive results. Probably erroneous positive results arose from assay A in all three categories and assay B in the second and third categories. These reactions were much more common after specimens had been heated to 56 degrees C for 30 min. Except that an anti-HLA DR4,B5-containing serum was repeatedly positive by C, assays C, D, and E apparently did not give rise to false-positive results. Results by these three assays were also highly reproducible. In tests on serum dilutions the highest titres were obtained by assays A and D, but assays C and E discriminated most clearly between anti-HTLV-III/LAV positive and negative sera. These two assays were rapid and convenient and seemed particularly suitable for testing blood donations. Assay D was almost comparable with them in performance but more difficult to use. The commercial assays C, D and E, an antibody capture assay, and a simple immunofluorescence test could be the basis for a methodologically diverse national system of primary and confirmatory testing for anti-HTLV-III/LAV.

Antibodies, Viral↗
PubMed1984

The heat sensitivity of hepatitis A virus determined by a simple tissue culture method.

A method for estimating residual infectious hepatitis A virus (HAV) after heat treatment of suspensions of the virus was devised. It made use of a readily maintained cell line (FRhK-4) in which the rate of release of HAV antigen into the tissue culture medium was directly proportional to the size of the inoculum. Loss of viral infectivity after heating could be estimated by inoculating heat-treated HAV suspensions into cell monolayers and measuring antigen released from the cultures during 5 weeks of incubation. An inoculum of 10(5) tissue culture infecting doses of HAV suspension in phosphate-buffered saline retained 1.0% of its infectivity after treatment for 2 min, and 0.01% after treatment for 4 min at 65 degrees C. The virus was fully inactivated within 4 min at 70 degrees C, 30 sec at 75 degrees C, 5 sec at 80 degrees C, and virtually instantaneously at 85 degrees C. When HAV was suspended in milk and subjected to statutory pasteurisation conditions, 0.1% of its infectivity remained after 30 min at 62.8 degrees C and 1.0% after 15 sec at 71.6 degrees C. The implications of these results for the heat treatment of food, water, and milk are discussed. It appears that recommended heat processes for milk and shellfish may not be adequate to inactivate HAV.

Animals↗
PubMed1984

Characterisation of a polyomavirus in two foetal rhesus monkey kidney cell lines used for the growth of hepatitis A virus.

Electron microscopy and prolonged incubation of cell cultures have revealed the presence of a papovavirus in two foetal rhesus monkey kidney cell lines, FRhK-4 and FRhK-6, which are used to grow hepatitis A virus. The papovavirus, designated FRKV, was present in culture fluids from both cell lines and in thin sections of FRhK-4 cells. The size of the virus, 47 nm, places FRKV within the Polyomavirus genus. FRKV has been grown in primary human embryo kidney and calf kidney cell cultures. Haemagglutinin has not been demonstrated. Preliminary investigations indicate that FRKV is antigenically identical to or closely related to stump-tailed macaque virus and is not one of the primate polyomaviruses SV40, SA12, BK or JC. FRKV reacts with antibody that occurs in pools of foetal and newborn bovine sera suggesting that the virus might be of bovine origin.

Animals↗
PubMed1984

Diagnosis of hepatitis A infection: comparative specificity of IgM capture assays using antigens derived from tissue cultures and marmoset faeces.

Hepatitis A virus (HAV) antigens from two tissue culture sources were compared with that from the faeces of infected marmosets to determine whether the former were satisfactory substitutes. Sera from 313 healthy blood donors and 417 patients with various clinical conditions were tested for IgM class antibody to HAV (anti-HAV IgM) using an IgM antibody capture assay (MACRIA) with each of the 3 antigens. Forty-eight specimens, all from cases of acute hepatitis, were positive in MACRIA with all 3 antigens. Only 2 of the 313 blood donors' sera reacted at all. These reactions were weak and did not arise with all antigens. Weakly reactive specimens were also found in 3 out of the 13 clinical categories. Overall 12 weak reactions arose with the faecal antigen and 8 and 7 with the two tissue culture antigens. Rheumatoid factor (RhF) was detected in 8 of the weakly reactive specimens and these had significantly higher titres of anti-HAV than sera known to contain RhF that were unreactive in MACRIA. It is concluded that tissue culture derived HAV antigen should replace that from primates on the grounds of quality, economy and convenience: also that non-specific activity in HAV MACRIA is usually due to a combination of RhF and high anti-HAV titres, but is infrequently strong enough to cause reactions interpreted as positive.

Animals↗
PubMed1983

Evidence for a bovine origin of the polyomavirus detected in foetal rhesus monkey kidney cells, FRhK-4 and -6.

Rabbit antisera to the stump-tailed macaque polyomavirus (STMV) which had been shown by immunoelectron microscopy and indirect immunofluorescence to react with the polyomavirus found in FRhK-4 cells (FRKV), also gave precipitin lines in counter-immunoelectrophoresis (CIE) and double diffusion in gel (GD) when reacted with FRKV. The reactions in GD showed identity with that of a rabbit antiserum to FRKV. Naturally occurring antibody to FRKV (anti-FRKV) was found by CIE in 48 per cent of 353 cattle, 1/106 pigs and 1/20 goats but not in any of 13 other species including 45 rhesus monkeys and 97 humans. Each of 9 anti-FRKV positive samples from cattle, the goat serum, but not the pig serum gave a line of identity with the rabbit antiserum to FRKV in GD against FRKV. Detection of anti-FRKV in colostrum deprived newborn calves and in commercial foetal calf sera (FBS) indicates that intra-uterine infection of cattle with FRKV may occur. FRKV adapted readily to growth in secondary calf kidney cultures and grew more rapidly and to higher titres than in the FRhK-4 cultures. We conclude that FRKV is probably another strain of STMV and that the natural hosts of these viruses are cattle and not primates. Evidence of intra-uterine infection of cattle implies that infectious FRKV may be present in some FBS and may thus have gained entry into various susceptible cell lines, particularly primate kidney.

Animals↗
PubMed1983

Report of a joint DMRQC/Organon field trial to detect hepatitis A IgM by ELISA.

The results of a field trial of a joint DMRQC/Organon ELISA kit for the detection of hepatitis A IgM antibody are reported. The participating laboratories were asked to use the kit to test a panel of 360 specimens consisting of duplicate coded samples of 180 sera. The panel was also tested by MACRIA in the Virus Reference Laboratory, Colindale. The ELISA was shown to be specific and sensitive giving good discrimination between acute and late convalescent hepatitis A sera. It was proposed that the same cut-off control as is used in the RIA (equivalent to 10 RIA units) should be adopted for the ELISA also.

Acute Disease↗