Investigation of hepatitis B virus transmission in a health care setting: application of direct sequence analysis

An epidemiologically linked cluster of hepatitis B virus (HBV) infections was investigated using HBV DNA amplification by a nested polymerase chain reaction with primers complementary to the region around the immunodominant a determinant of the surface gene, part of the X and core genes, and precore region and direct nucleotide sequence analysis. The cluster, in which 2 persons died of fulminant hepatitis, comprised 1 blood donor, 2 patients, and 2 health care workers. The Kimura two-parameter method was used to compare variance among the cluster with that in the control samples, which were collected from 7 patients infected with the same HBV subtype. Significantly less variation occurred within the cluster than in the control group (unpaired t test, P < .05). In an unrooted phylogenetic tree analysis, the 5 study samples formed a cluster distinct from the controls. This direct molecular approach of analyzing conserved regions of the HBV genome differentiated between viruses involved in HBV transmission events.

Detection of herpesvirus DNA by nested polymerase chain reaction in cerebrospinal fluid of human immunodeficiency virus-infected persons with neurologic disease: a prospective evaluation

A nested polymerase chain reaction-based method was used prospectively to detect herpesvirus DNA in cerebrospinal fluid (CSF) from 111 patients with AIDS, 39 of whom had a suspected diagnosis of cytomegalovirus (CMV)-associated neurologic disease (patients with encephalopathy, polyradiculopathy, or peripheral neuropathy) and 72 who had alternative diagnoses. CSF from 24 (62%) of the patients with suspected CMV-associated disease had detectable CMV DNA compared with only 8 (11%) of the patients with other diagnoses. Varicella-zoster virus DNA was detected in CSF from 3 patients (2 with myelitis and 1 with encephalitis), all of whom had recent cutaneous zoster. No CSF specimen contained detectable herpes simplex virus type 1 DNA, and none of the patients with myelitis had detectable herpes simplex virus type 2 DNA in CSF. This study demonstrates a significant association between detectable CMV DNA in CSF and suspected CMV-associated neurologic disease in patients with AIDS.

Hepatitis B transmission from contaminated cryopreservation tank

Over a 25-month period, six multiply transfused patients undergoing cytotoxic treatment for haematological or other malignant disorders developed icteric acute hepatitis B virus (HBV) infection. Bone marrow or peripheral-blood stem cells had been harvested from all six patients and stored in the same cryopreservation tank for possible future transplantation. Human DNA, HBsAg, and HBV DNA with sequences identical to those from four patients with related infections were subsequently found in the liquid nitrogen. Leakage of the cryopreservation bags used to store bone marrow harvested from the first patient when acutely infected with HBV led to contamination of the tank and its contents with HBV and subsequent transmission to patients after transplantation. This incident emphasises the continuing need to screen donors of tissue to be cryopreserved for bloodborne virus infections. It also reinforces the requirement for primary containers used to cryopreserve human tissue to be sealed in a way which prevents exchange of material between the specimen and the liquid nitrogen.

HIV-1 RNA serum-load and resistant viral genotypes during early zidovudine therapy

The response of HIV-1 to initial zidovudine (ZDV) treatment was assessed in 11 patients with severe HIV disease. We quantified serum HIV-1 concentrations and mutations associated with ZDV resistance by culture-independent methods. There was a prompt fall in serum HIV-1 RNA within 1-2 days of treatment with maximum suppression by seven days, which was paralleled by changes in serum p24 antigen (p24 Ag). Serum RNA started to return to pretreatment levels within weeks. The HIV reverse transcriptase (RT) gene in most patients developed mutations associated with drug resistance within months and as early as 25 days on therapy in one patient. The codon changes were not sufficient to explain the early return of serum HIV-1 RNA levels and their patterns continued to evolve after patients stopped taking ZDV. The significance of these findings is discussed in relation to the limited long-term efficacy of ZDV. The dynamic time course of viral load and RT responses to ZDV is of particular importance in short-term interventions such as pregnancy.

The detection of varicella zoster antibodies by simultaneous competitive EIA and its comparison with radioimmunoassay, latex agglutination and antiglobulin type EIA

A rapid and simultaneous competitive enzyme immunoassay (EIA) for the detection of human antibodies to varicella zoster virus (VZV) which utilises complement fixing (CF) VZV antigen and peroxidase labelled human antibodies to VZV as reagents is described. The competitive EIA was compared with competitive radioimmunoassay (RIA) in a selection of sera from 501 blood donors and 115 patients. The competitive EIA was comparable in sensitivity and specificity to the RIA, but had the advantage of not requiring radiolabelling or facilities for radioactive handling and disposal, and also had an enhanced stability. The competitive EIA was compared with competitive RIA, a commercially available latex agglutination assay and an antiglobulin type EIA on sera from 100 patients. The competitive EIA and RIA appeared to be the most sensitive tests.

Novel application of a point mutation assay: evidence for transmission of hepatitis B viruses with precore mutations and their detection in infants with fulminant hepatitis B

Mutations of the precore region of hepatitis B virus (HBV) genome have been associated with fulminant and severe chronic hepatitis. However uncertainty remains about the clinical significance and transmissibility of these mutant strains. A point mutation assay (PMA) was developed to identify qualitatively and quantitatively mutations affecting precore amino acids 1 and 28. We have analysed serum samples from six mother-infant pairs where perinatal transmission of HBV has occurred and where the mothers were HBV carriers without detectable serum HBeAg. In three cases fulminant hepatitis developed in the infant, in two cases acute hepatitis resolved, and in one case the infant was immunised and did not become infected. We also examined serum from a healthcare worker, an anti-HBe-seropositive HBV carrier, believed to have transmitted HBV infection to a patient. The PMA results were confirmed in all cases by direct sequencing of polymerase chain reaction (PCR) products using nested and double-nested PCR with primers to the precore and X region. Precore aa28 mutant-type virus was detected in the serum of one mother at the time of delivery of three of her children, two of whom developed fulminant hepatitis. Another mother of an infant with fulminant hepatitis had no precore mutations. In one mother-infant pair a mixed viral population was found; the acute hepatitis B in the infant resolved. The HBV sequence from the healthcare worker was also of aa28 mutant type. No mutations of aa1 were detected in any of the specimens. The study supports the association of precore mutations with some cases of transmission of HBV infection from HBeAg-negative mothers to their infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitreous fluid sampling and viral genome detection for the diagnosis of viral retinitis in patients with AIDS

Cytomegalovirus (CMV) causes severe necrotizing retinitis in patients with the acquired immune deficiency syndrome (AIDS) and other herpesviruses have been implicated in the acute retinal necrosis syndrome (ARN), seen in both the immunocompetent and the immunosuppressed. At present the diagnosis of viral retinitis relies solely on clinical appearances. In order to assess whether the detection of herpesvirus-specific DNA in cell-free vitreous biopsy samples could be useful in the early diagnosis of viral retinitis, vitreous fluid samples were taken from 100 patients. Fifty patients had AIDS as defined by the Centers for Disease Control, (MMWR 36 (suppl 1S):1S-15S, 1987) and retinal disease. The remainder were not known to be HIV infected and had no clinical evidence of retinal infection. Each sample was tested for the presence of CMV, herpes simplex virus 1 (HSV-1), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), and human herpesvirus 6 (HHV6), by amplification of viral DNA using a sensitive and specific nested polymerase chain reaction (PCR). The presence of detectable CMV or VZV DNA was clearly associated with clinical disease whereas the presence of HSV-1, EBV, and HHV6 sequences were not. Clinical discrimination between CMV- and VZV-associated retinitis was greatly enhanced when the PCR results were taken into consideration.

Clustering of human T lymphotropic virus type I seropositive in Montserrat, West Indies: evidence for an environmental factor in transmission of the virus

A community survey of human T cell lymphotropic virus type I (HTLV-I) in Montserrat, West Indies, identified 22 instances in which 2 HTLV-I-seropositive adults lived within 60 m of each other (close pairs), compared with 7.8 expected (P < .001). Five of these close pairs were mother-offspring or husband-wife. The remaining 17 pairs were of unrelated members in separate households. The percentages of male-female (41%), female-female (41%), and male-male (18%) types in these 17 pairs were very similar to those among the 1377 similarly defined pairs in which neither or only 1 member was seropositive, affording no support for extramarital heterosexual activity as an explanation for the clustering observed. Thus, the demography of HTLV-I was not accounted for completely by sexual and mother-to-offspring transmission. The predominance of clustering of unrelated HTLV-I-seropositive individuals in locations with high mosquito infestation raised the possibility of sporadic transmission of HTLV-I by hematophagous insects.

Hepatitis C virus infection in haemodialysis patients: a clinical and virological study

A cohort of 66 patients on maintenance haemodialysis was examined for serological (anti-HCV) and virological (HCV-RNA) evidence of infection with hepatitis C virus (HCV). Nine (13.6%) were anti-HCV positive, all of whom had detectable HCV-RNA in their serum. Statistical analysis of various risk factors (including length of time on haemodialysis, history of blood transfusion, history of renal transplantation and of previous hepatitis B infection) showed that only the length of time on haemodialysis was significantly associated with the acquisition of HCV infection. Genotypic analysis showed that five patients were infected with genotype 1 and a further two were infected with genotype 4. The latter finding is of significance because strains of genotype 4 are extremely uncommon in Western Europe. These results demonstrate that intra-unit transmission of HCV-infection took place in a group of patients on maintenance haemodialysis.

Conservation of precore and core sequences of hepatitis B virus in chronic viral carriers

Mutations in the precore region of hepatitis B virus (HBV) have been associated with failure of expression of HBV e-antigen (HBeAg), however, the prevalence of these and other mutations in HBV carriers without overt chronic liver disease remains uncertain. Homosexual or bisexual males (n = 65) with chronic HBV infection attending The Middlesex Hospital, London were studied, of whom two had clinical evidence of chronic liver disease. HBV DNA was amplified from 62 of 65 serum samples using nested and double nested polymerase chain reaction (PCR) assays. Direct sequencing of the PCR products was employed to investigate sequence variation. HBV-DNA from all available HBeAg-negative (n = 9) and selected HBeAg-positive (n = 33) sera were sequenced in the entire precore gene, the 3' terminal portion of the X gene (aa128-154), and the 5' terminus of the core gene (aa18-73). Sequences were highly conserved in all regions studied. Samples from two anti-HBe-seropositive patients contained mutations in the precore region. In one, a single mutation in the first amino acid resulted in a change to leucine, which would prevent translation of this region and therefore HBeAg expression. Wild type sequences were also detected in this sample. In the other sample from a patient with overt chronic liver disease, a mutation of precore amino acid 28 changed a tryptophan residue to a stop codon which would also prevent HBeAg expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of antibodies to human T cell leukaemia/lymphoma virus in blood donors in north London

OBJECTIVES

To determine the prevalence of antibodies to the human T cell leukaemia/lymphoma viruses (HTLV-I and HTLV-II) in blood donors in north London in order to assess the economic impact and the logistic effects that routine screening would have on the blood supply.

DESIGN

All donations collected by the north London blood transfusion centre between January 1991 and June 1991 were screened for antibodies to HTLV-I and HTLV-II by modified, improved Fujirebio gel particle agglutination test. Positive samples were titrated and retested as necessary.

SUBJECTS

96,720 unpaid volunteers, who gave 105,730 consecutive donations of blood and plasma.

SETTING

North London blood transfusion centre.

MAIN OUTCOME MEASURE

Observed numbers of donors confirmed to be seropositive for HTLV by reference laboratories.

RESULTS

Of 2622 (2.5%) initially reactive samples, 414 (0.4% of all samples) gave a titre of > or = 1 in 16 on the modified agglutination test. Thirty five of the 414 serum samples yielded positive results on one of two enzyme linked immunosorbent assays (ELISA (Cambridge Biotech and Abbot)), and none of these results were confirmed by either reference laboratory. Five samples yielded positive results on both ELISAs and all five of these were confirmed to contain antibodies to HTLV. One of the five contained antibodies to HTLV-II and the others antibodies to HTLV-I. Four seropositive donors were white women whose only risk factor for infection was sexual contact. The fifth (positive for antibodies to HTLV-II) was an Anglo-Caribbean man who admitted to previous misuse of intravenous drugs.

CONCLUSION

The prevalence of antibodies to HTLV in blood donors in north London was one in 19,344 (0.005%). Up to 100 donors a year might be identified in the United Kingdom as being infected with HTLV, although prevalence in different regions may vary considerably.

Hepatitis C viral RNA in clotting factor concentrates and the development of hepatitis in recipients

The polymerase chain reaction (PCR) was used to detect hepatitis C (HCV) viral sequences (HCV-RNA) in clotting factor concentrates that had been stored at 4 degrees C for 1 to 16 years. A total of 43 concentrates were tested, comprising 31 batches of factor VIII, 6 of factor IX, 2 of antithrombin III, 3 of FEIBA, and 1 of factor VII. HCV-RNA was detected in 13 of the 43 batches (30.2%). Concentrates that had not undergone viral inactivation during manufacture were significantly more likely to contain detectable HCV-RNA than concentrates that had been virally inactivated (56.3% v 14.5%, P = .006). HCV sequences were more commonly detected in concentrates made from paid donor plasma than in those made from volunteer donor plasma (44% v 11%, P = .041), and more commonly in virally inactivated concentrates with pre-1989 than with post-1989 expiration dates (50% v 0%, P = .004). Of the four batches of heat-treated products that were HCV-RNA positive, at least three transmitted non-A, non-B hepatitis (NANBH). An association between the presence of HCV-RNA in concentrates and the development of NANBH was demonstrated in nine previously untreated patients on prospective follow-up. HCV-RNA was detected in the concentrates administered to the six patients whose alanine aminotransferase (ALT) abnormalities met the diagnostic criteria for NANBH and who later seroconverted for HCV, but it was not detected in the concentrates administered to the three patients whose ALT abnormalities failed to satisfy the diagnostic criteria and who did not seroconvert. We suggest that the use of this PCR technique to monitor clotting factor concentrates derived from pooled blood may potentially contribute to product safety.

Acute hepatitis C infection in patients undergoing therapy for haematological malignancies: a clinical and virological study

Patients receiving multiple transfusions are at risk of acquiring hepatitis C (HCV) infection from a donor population which is unscreened for hepatitis C antibodies (anti-HCV). Prior to the introduction of blood donor screening for anti-HCV in the U.K., a group of patients undergoing therapy for haematological malignancies, with repeatedly abnormal liver function tests, were investigated for acute HCV infection. Thirty-two patients had repeatedly raised serum transaminases, and eight of these (25%) had evidence of an acute HCV infection. The diagnosis was made by the detection of HCV-RNA in the patients' serum using a complementary DNA/polymerase chain reaction (cDNA/PCR) procedure. All eight patients had received myeloablative chemotherapy and three had undergone bone marrow transplantation. HCV infection contributed significantly to the morbidity of this group of patients in the short term whilst they were undergoing treatment for their underlying haematological condition. The long-term effects have yet to be evaluated. In an attempt to decrease hepatic damage due to HCV, three patients were placed on interferon therapy. None showed a sustained reduction in serum transaminases or HCV viraemia. It is hoped that the introduction of anti-HCV screening of blood donors, will reduce the frequency of transfusion-acquired HCV infections. Early observations suggest that this is the case, as we have seen no new cases of HCV infection in our unit since the introduction of donor screening in September 1991.

Enzyme-linked immunosorbent assays for the measurement of human immunodeficiency virus, type 1 reverse transcriptase antigen and antibodies

Enzyme-linked immunosorbent assays (ELISA), using recombinant HIV-1 reverse transcriptase (RT; p66), are described for the measurement of RT antigen and serum antibodies to RT (anti-RT). The ELISA for anti-RT was developed in qualitative and quantitative forms, both were highly specific (100%, 0/859; 99.6%, 3/859), the former was sensitive (100%, 364/364) detecting the highest dilution of a standard high titre anti-HIV-1 RT antibody positive control serum. The latter was less sensitive (97.2%, 354/364) detecting lower dilutions of the antibody control, but had the advantage of producing highly reproducible optical density/concentration curves for the quantification of unknown anti-RT samples. In a cross-sectional study of 191 patients with HIV-1 infection, all patients developed anti-RT antibodies in CDC disease group II and III that declined but persisted in all cases into CDC disease group IV. The RT antigen assay was specific (100%, 0/772) and sensitive detecting 6 to 15 pg/ml of recombinant RT antigen diluted in normal human serum. No cross-reactivity using the RT antibody and antigen assays was seen in sera from 85 patients with current or previous hepatitis B infection or 21 sera from patients with HIV-2 infection. Further, no reactivity was demonstrated with the assays in a cohort of 20 seronegative partners (320 samples) exposed to HIV-1 infection over a 4-yr period. In samples from a patient with documented seroconversion, RT antigen was the first detectable marker of HIV-1 infection and was followed by a prompt anti-RT response. Serum RT antigen disappeared or remained low in most patients during CDC disease group II and III and rarely reappeared with progression to CDC disease group IV. In tissue culture studies RT antigen was detected in supernatant within 12 h (75 pg/ml), gave an initial peak at 36 h (300 pg/ml) and then continued to rise up to 5 days (603 pg/ml), offering a simple, cost-effective alternative to existing methods.

HIV-1 plasma viraemia quantification: a non-culture measurement needed for therapeutic trials

Accurate measures of inhibition of virus replication are needed to evaluate the efficacy of antiretroviral agents in large clinical trials. We describe an accurate, economical and rapid method for the direct detection and quantification of cell-free human immunodeficiency virus type -1 (HIV-1) in serum or plasma. The method includes affinity capture of the virus by latex microparticles coated with HIV-1 envelope-specific antibodies, reverse transcription primed by an HIV-1 specific oligonucleotide and amplification by nested PCR of the synthesised cDNA. We show that the method can be applied to large numbers of serum samples, is reproducible and is highly applicable to the monitoring of viral load in HIV-1 infected patients, especially during the investigation of drug efficacy.

Detection of herpesvirus DNA in the large intestine of patients with ulcerative colitis and Crohn's disease using the nested polymerase chain reaction

The prevalence of herpesvirus DNA was examined in inflammatory bowel disease tissue. DNA was extracted from resection and biopsy specimens of the large intestine from patients with ulcerative colitis (n = 21), patients with Crohn's disease (n = 29), and patients with noninflammatory bowel disease (controls) (n = 21). The nested polymerase chain reaction was used to detect viral DNA using primer pairs specific for either cytomegalovirus (CMV), herpes simplex virus 1 (HSV1), human herpesvirus 6 (HHV6), varicella zoster virus (VZV), or Epstein Barr virus (EBV). HSV1 and VZV DNA were not detected in any of tissue samples. There was a high prevalence of CMV (81%), HHV6 (76%), and EBV (76%) DNA in ulcerative colitis tissue compared to Crohn's disease tissues (CMV 66%, HHV6 45%, EBV 55%). Control tissue had a relatively low frequency of CMV (29%) and EBV (19%) DNA but a prevalence of HHV6 DNA similar to that of ulcerative colitis (86%). However, the simultaneous presence of HHV6 and CMV and/or EBV DNA in ulcerative colitis tissue (76%) was much greater than in either Crohn's disease tissues (38%) or control tissue (29%) (P < 0.05). There was a low prevalence of CMV, HHV6, and EBV DNA in peripheral blood mononuclear cells from all patient groups. CMV and EBV are capable of reactivating HHV6: the high prevalence of coexistent HHV6 infection with either or both of these two viruses in ulcerative colitis tissue suggests that they may play a synergistic role in the pathogenesis of this disease.

A microtitre format point mutation assay: application to the detection of drug resistance in human immunodeficiency virus type-1 infected patients treated with zidovudine

An assay for the analysis of point mutations in DNA fragments amplified by the polymerase chain reaction is described. The method was applied to the analysis of mutations leading to single amino acid changes in the reverse transcriptase gene of human immunodeficiency virus type-1 that are associated with decreased sensitivity of the virus to the effects of the nucleoside analogue zidovudine. The assay uses a microtitre format allowing large numbers of clinical samples to be analysed, and is a quantitative assay giving information on the relative proportions of wild-type and mutant sequence at the point being analysed. The analysis of mutations in codons 67, 70, 215, and 219 of the RT gene in samples taken at various time points after the commencement of zidovudine therapy shows a high variability in the rate at which these mutations arise and in the proportions of wild-type and mutant sequences observed. The method we describe has wide application to the analysis of other point mutations in clinical or research studies.

Comparison of three immunoassays for the detection of anti-HHV6

Sera from 96 blood donors were tested for antibody to human herpesvirus 6 by indirect immunofluorescence (IF), circle immunoassay (CIA) and competitive radioimmunoassay (RIA). The correlation between the three assays was good but the CIA and competitive RIA were more sensitive for the detection of HHV6 antibody than indirect IF. The crossreaction of HHV6 antibody with that to the other human herpesviruses was also studied in this blood donor group. No correlation was found between antibody to human herpesvirus 6 by any of the methods described and antibody to any of the other human herpesviruses in these sera.