P.P. Mortimer

Human parvovirus arthropathy.

19 of 153 patients attending an early-synovitis clinic were shown to have been recently infected by the human parvovirus (HPV). 5 other patients had evidence of some other closely preceding infection. HPV-infected patients typically presented with symmetrical peripheral polyarthropathy of sudden onset and moderate severity. Usually there was some improvement within 2 weeks, but in 17 patients symptoms persisted for more than 2 months, and in 3 for more than 4 years. Arthropathy in the absence of the facial rash that characterises HPV infection in children is a common presentation of the infection in adults.

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.

HEPATITIS C VIRUS ANTIBODY

The present invention relates to polyclonal and monoclonal antibodies which selectively bind to antigens associated with hepatitis C viral particles or HCV aggregated antigens isolated from infected patients and to processes which may be used to isolate hepatitis C virus from infected patients including a procedure by which HCV is partially purified. The use of these antibodies in diagnostic immunological assays is also described.

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.

HTLV-III antibody in Swiss and English intravenous drug abusers.

The authors compared the prevalence of human T-lymphotropic virus type III (HTLV-III) antibody in intravenous drug abusers in Switzerland and England. Serum samples collected in 1979-85 from 296 individuals from Bern Switzerland and samples collected in 1985 from 236 individuals in England were tested by competitive radioimmunoassay. Positive results were confirmed by immunofluoresence or by commercial enzyme immunoassay. In the Bern sample antibody 1st appeared in drug abusers sera in 1982; by 1984 the prevalence had risen to 42%. In England the prevalence in early 1985 was 6.4%. 90% of the anti-HTLV-III-positive Swiss drug abusers and 75% of the corresponding British subjects had markers of hepatitis B virus infection. A possible explanation for the higher prevalence of HTLV-III infection in Swiss drug abusers is that HTLV-III was introduced into the drug culture later in England than in Switzerland due to less contact between between homosexuals and drug users in the former country. The presence of HTLV-III infection in a population that is largely heterosexual raises the possibility of spread through sexual intercourse from this group to the rest of the heterosexual population. Health education should be targeted at present and potential intravenous drug abusers to prevent further increases in the incidence of acquired immunodeficiency syndrome (AIDS).

RATIONAL PROGRAMME FOR SCREENING TRAVELLERS FOR ANTIBODIES TO HEPATITIS A VIRUS

A blood test and a saliva test for antibody to hepatitis A virus (anti HAV) were offered to British travellers seeking human normal immunoglobulin (HNIG) prophylaxis. The specimens were tested by an IgG capture and a competitive radioimmunoassay (GACRIA, COMPRIA). By GACRIA 211 subjects were anti-HAV positive and 358 anti-HAV negative on both serum and saliva. 10 other seropositive subjects had weakly positive saliva reactions. There were three discrepant results. For the population investigated HNIG use could be minimised at no extra cost by first testing the saliva of those greater than 40 years old, frequent or long-stay travellers, those born in HAV endemic areas, and those with a history of jaundice. Of the 51% of travellers tested for these reasons 20% were anti-HAV positive. They made up 76% of all those with antibody.

THE INFLUENCE OF DENTAL STATUS ON THE DETECTION OF IgG CLASS ANTI-VIRAL ANTIBODIES IN HUMAN SALIVA

An antibody-capture radioimmunoassay was used to measure levels of IgG class antibodies to rubella and hepatitis A viruses in serum and saliva of 30 edentulous, 30 partially dentate and 31 dentate individuals. The prevalence of seropositivity for rubella was 98.9 per cent and for hepatitis A 73.6 per cent. The serum reactivities were generally greater than those for saliva. There were 8 false-negative results for saliva out of the 182 tests performed, of which 4 were in the edentulous group, 3 in the partially dentate and 1 in the dentate group. For both rubella and hepatitis A virus antibodies the (geometric) mean ratios between the saliva and serum reactivities were similar across the three dental groups. The values for sensitivity, specificity and positive predictive value suggest that assay of saliva for antiviral IgG antibody is a satisfactory technique regardless of dental status.

PREVALENCE OF ANTI-HTLV-III IN UK RISK GROUPS 1984/85

Of over 12000 diagnostic specimens tested for anti-HTLV-III/LAV in the UK in the year to September 1985 17% were positive. This is the broadest based evidence yet of the dissemination of HTLV-III through Britain. Specimens were referred from sexually transmitted disease (STD) clinics from treatment centers for hemophilia and from physicians treating intravenous drug abusers. They were tested by competitive radioimmunoassay (RIA) and positive results were confirmed by capture RIA or immunofluorescence. Among identified homosexual clinic attenders in the samples the prevalence of anti-HTLV was over 20% and rose during the year. In a large unspecified group but mainly of homosexual men attending provincial STD clinics it was 11%. In one separately analyzed central London clinic it was 35% (n=432). The difference in prevalence of HTLV-III antibody between London and the rest of the country remains though during 1984/85 the prevalence in homosexuals rose both in and outside London. Our sample of drug abusers also shows a higher anti-HTLV-III prevalence than that found in previous years though it is too small to be dependable. However the evidence of high and rising prevalences in the cities of mainland Europe and in Edinburgh suggests that the infection could soon be widespread in British drug abusers. By contrast no rise in prevalence since 1984 has been found in tests on hemophiliacs. This probably reflects the change in gtreatment with heat-treated factor VIII concentrate. Preventive measures have thus stemmed the spread of HTLV-III in only one small group hemophilia patients. The continued spread of infection in other groups suggests that despite hard work by voluntary organizations and continual media attention understanding of the the scale and seriousness of the HTLV-III epidemic is still incomplete. A more direct and comprehensive exercise in health education is urgently called for. Testing for anti-HTLV-III until recently confined to a few laboratories in Britain is now countrywide. This will make serological data harder to gather but they ought to be collected nevertheless both to provide the rationale for behavior modification by the main risk groups and to signal any general changes in the pattern of infectionin the community. (full text)

Variation in the sensitivity of HBsAg screening kits

Summary. Fifteen HBsAg kits from 14 manufacturers were assessed. Their sensitivity was evaluated by testing 150 HBsAg‐positive sera, sera from four donors who were low‐level HBsAg carriers, and sequential specimens from 22 seroconverting individuals together with dilutions of six of these specimens. The British HBsAg Working Standard (0.5IUmL‐1) and the NIBSC/UKBTS HBsAg Monitor Sample (0.125IUmL‐1) were also tested. Five assays failed to detect one of the 150 routine HBsAg‐positive sera. Four assays (Auszyme Monoclonal; Monolisa Ag HBs 2nd generation; Murex HBsAg; Ortho HBsAg Test Systems 3) were able to detect HBsAg in all but one of the six sera from low‐level carriers, whereas one assay (MicroTrak II HBsAg) detected only one of the six. The most sensitive kit (Monolisa Ag HBs 2nd generation) detected HBsAg in 79 specimens from the seroconversion panels; four other kits detected HBsAg in at least 70 specimens, seven in 60–69, two in 50–59 and the least sensitive in 31. Further analysis of the findings on seroconverters indicated a median reduction in the duration of HBsAg detection of 5 days or more for four assays when compared with the most sensitive assay. One kit (Auszyme Monoclonal) detected HBsAg in 15 of the 18 dilutions prepared from the seroconversion specimens, whereas three kits detected HBsAg in fewer than 10 dilutions. Two kits gave negative reactions with the British HBsAg Working Standard on all of five occasions and six were consistently unreactive with the NIBSC/UKBTS HBsAg Monitor Sample; only three kits (Bioelisa, Enzygnost, Murex) were always reactive. There is therefore substantial variation in sensitivity among the HBsAg kits currently available.

HIV INFECTION, BREASTFEEDING, AND HUMAN MILK BANKING

The advice of a circular published by the British Department of Health (DHSS), suggesting that all women at high risk of being exposed to HIV not breastfeed their children has prompted discussion of safety of breastfeeding and milk banking. Vertical transmission of HIV from mother to infant via breastfeeding is not proven: only a few cases of infants seroconverting in women having tested negative during pregnancy have been reported. In contrast, intrauterine or intrapartum transmission is known to occur, and HIV has been isolated from cervical secretions, placenta, amniotic fluid, and the uterine cervix. It is discriminatory to categorize all women of certain nationalities, socioeconomic groups, etc. As high risk, when prenatal HIV screening is not being done. Many of these multiply deprived women are those whose children would most benefit by breastfeeding. The DHSS circular also suggests that donors of breast milk be screened for HIV, and that milk be kept in cryostorage for 3 months. Pasteurization of human milk by the Vickers Medical or the Axicarew Colgate Medical Pasteuriser effectively eliminates HIV. Therefore even milk donors do not need to be labeled screened. The DHSS circular establishes an unnecessarily discriminatory policy.