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SUMMARY The hepatitis E virus (HEV) is a major cause of acute hepatitis globally. Genotypes 1 and 2 (G1 and G2) are obligate human pathogens transmitted faeco-orally, leading to epidemics in developing countries. In contrast, genotypes 3 and 4 (G3 and G4) have a wider host range, including humans, but are primarily porcine viruses and are transmitted from animals to humans as a food-borne zoonosis when meat from an infected animal is consumed. HEV is increasingly recognised as a problem in developed countries, including countries in Europe. G3 HEV is now the most common cause of acute viral hepatitis in the UK and cases continue to rise. The majority of these infections are acquired within the UK and thought to be from insufficiently cooked meat, predominantly processed pork meat. Previously thought to only cause self-limiting disease, HEV infection can persist in immunosuppressed patients, which may lead to chronic hepatitis and the rapid development of cirrhosis. Of particular interest to the transfusion community has been the possibility of transfusion-transmitted HEV, which has been reported from countries classically considered HEV-endemic but also non-endemic countries in Europe and Japan. This has prompted some countries to introduce screening for HEV in blood donations.

South London Specialist Virology Centre, King’s College Hospital, Denmark Hill, London SE5 9RS, United Kingdom Virus Reference Department, Microbiology Services Colindale, 61 Colindale Avenue, London NW9 5HT, United Kingdom Department of Histopathology, King’s College Hospital, Denmark Hill, London SE5 9RS, United Kingdom Department of HIV/Genitourinary Medicine, King’s College Hospital, Denmark Hill, London SE5 9RS, United Kingdom Department of Haematological Medicine, King’s College Hospital, Denmark Hill, London SE5 9RS, United Kingdom

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.

Background and Objectives Certain patient ethnic groups may require blood components from donors under-represented in the UK donor population. Selective recruitment of Afro-Caribbean donors is therefore necessary but was considered to pose an increased risk of human T-cell leukaemia/lymphoma virus (HTLV) infection. To assess this a seroprevalence study of HTLV was undertaken in Afro-Caribbean and Caucasian donors.Materials and Methods Sera from 1100 Afro-Caribbean and 1100 Caucasian donors were tested for antibody to HTLV. Reactive samples were confirmed for specificity using an algorithm comprising two additional assays and polymerase chain reaction (PCR) where possible.Results Six Afro-Caribbean donors (0.55%) were considered to be infected with HTLV I.Conclusion Donor selection in this case caused a significantly elevated prevalence of HTLV infection and serves as a warning of the need for care in the design policies for selective donor recruitment.

SUMMARYBetween March and June 2008, 12 cases of hepatitis A were notified in Winchester. Cases were from a primary school and a nursery school with no direct linkage. Hepatitis A virus (HAV) RNA sequenced from nine cases confirmed the strain in both schools to be identical. The outbreak could have affected three other schools and a maternity unit and was controlled by immunization and screening of neonates in the maternity unit by dried blood spots. No neonates were infected and no further cases were reported until 5 months later when the index case's mother became infected with same strain of virus associated with the outbreak despite vaccination. Neither the source of the outbreak or the subsequent infection of the index case's mother was identified; however, with the timing of the cases continued transmission in the community by children with asymptomatic infection or a recurrent source cannot be ruled out.

SUMMARYThe cross-reaction of HHV6 antibody with that to the other herpesviruses was studied in 96 blood donors whose sera were tested for IgG antibody to human herpesvirus type 6 (HHV6), cytomegalovirus (CMV), Epstein–Barr virus (EBV), varicella zostervirus (VZV) and herpes simplex virus (HSV). No correlation was found between IgG antibody to HHV6 and that to any of the other herpesviruses in these individuals. Antibodies to HHV6 and CMV were measured in patients undergoing documented serological responses to HHV6. Eleven cases of primary HHV6 infection associated with roseola infantum in babies, 1 of whom suffered from gastroenteritis as well as pyrexia and rash, are reported. Three cases of HHV6 reactivation, 1 in a 3-year-old child and 2 in adults, 1 of whom simultaneously underwent a primary CMV infection are also reported. Our results suggest that indirect immunofluorescence is a specific way of measuring HHV6 antibody, that HHV6 IgG and IgM can be detected in the absence of antibody to CMV and that HHV6 IgM is present both in primary HHV6 infections and in reactivations.

To date, 11 HIV-1 M group clades, A to K, have been characterized, displaying different distributions, prevalences, and biological properties. Approximately 90% of new HIV-1 infections occur in developing countries, including the Caribbean. However, information on HIV-1 subtypes from this region is limited. We report subtype characterization of viruses from 71 individuals, obtained during the period 2000–2002. RNA from the pol region was sequenced, generating data on subtype and drug resistance associated mutations for 71 specimens from 9 countries. Sixty-seven (94.4%) sequences were classified as clade B, three (4.2%) as D/B, and one (1.4%) as clade C. Numerous polymorphisms were observed, including some associated with drug resistance, but not signifying exposure to chemotherapy. This study adds to our knowledge of HIV-1 clades in the Caribbean, and indicates possibilities for monitoring HIV-1 chemotherapy.

The sensitivity of nine commercial assays, Western blot, and a newly developed monoclonal antibody-based assay for antibody to human T lymphotropic virus type III/lymphoadenopathy associated virus (anti-HTLV III/LAV) were evaluated using a panel of mainly weak-positive sera. In tests on 20 sera three commercial assays and a monoclonal-based assay, representing two different solid-phase methodologies, were found to be more sensitive than Western blot. Our findings suggest that Western blot cannot be depended upon as the sole confirmatory test for anti-HTLV III/LAV. The continued use of the more sensitive enzyme-linked immunosorbent assays (ELISAs), particularly those of dissimilar methodology, would be a more valid approach to confirmatory testing.

SUMMARYEight sera from 125 cases of infectious mononucleosis (IM) were reactive for rubella-specific IgM in an M-antibody capture radioimmunoassay. The reactivity of individual sera varied depending upon the source of the rubella antigen used in the assay. One serum gave strongly positive results with some rubella haemagglutinating antigens but negative results with others and may have contained an IgM antibody which was capable of distinguishing between strains of rubella virus.If the diagnosis of rubella is based solely on detection in solid-phase immunoassay of rubella-specific IgM, IM should be excluded.

SUMMARYHybridomas secreting monoclonal antibodies to HBsAg and HBcAg were prepared from immunized mice. An antibody capture radioimmunoassay was used to detect and select appropriate hybrids for propagation and cloning. The advantages of this assay were discussed. The resulting monoclonal antibodies were compared with conventional polyclonal antisera for the detection of virus antigens in liver tissue and found to give excellent results.

SUMMARY. Antibodies specific for rubella virion polypeptide, VPI, secreted by clones of hybridoma cells or produced in rabbits in response to specific antigenic stimulation, located determinants for haemagglutination inhibiting (HI) and neutralising (Nt) antibodies on this envelope component.

The aetiology of acute anterior uveitis (AAU) in the great majority of cases is unclear. Various infective agents have been postulated, however, as playing a direct or indirect part in the disease process, possibly via an immune-complex vasculitis. In an earlier study we concluded that, contrary to a previous report, hepatitis B virus (HBV) played only a small role, if any, in the pathogenesis of uveitis in Great Britain. Since we did not look for other markers of HBV infection other than hepatitis B surface antigen (HBsAg), it is possible that some cases of recent HBV infection may have been missed. In the present study 49 patients with AAU were tested for markers of hepatitis B infection. Sera from all patients tested were found to be negative for HBsAg and for antibody to the HBV core (anti-HBc), excluding HBV as a significant cause of AAU in this country. Since the quest for an infective agent in AAU may remain unproductive, future research on the aetiopathogenesis of AAU should include the study of tissue 'vulnerability' and the local and systemic immunoregulatory factors which modulate inflammatory responses.

A renal transplant patient was infected by a transfusion of blood from a chronic carrier of hepatitis B and he also became a symptomless carrier. Stored sera enabled detailed retrospective measurement of the rate of decline of passively transferred HBsAg, anti-HBc, and anti-HBe. Active HBsAg production was detected after two months and anti-HBc after six months; neither HBe nor anti-HBe was actively produced although there were many 42 nm HBV particles in the patient's serum.

The sequences encoding the p24 core protein of human immunodeficiency virus type 1 were identified in a cDNA library made from infected CEM cells. The nucleotide sequence of the DNA coding for p24 was shown to be very similar but not identical to the sequences of lymphadenopathy virus and human T-cell leukaemia virus type IIIb. These sequences were expressed in Escherichia coli at the amino terminus of beta-galactosidase and used to screen a panel of monoclonal antibodies raised against virus-expressed p24. Regions containing the epitopes of five of the monoclonal antibodies were located using a series of amino- and carboxy-terminal deletion mutants of the recombinant p24 protein.

SummaryMice were immunized by three intraperitoneal and one intravenous injection of rubella haemagglutinin. Splenocytes from these mice were fused with the cells of a syngeneic myeloma cell line, and following culture for various periods of time, single-cell clones were derived by the technique of limiting dilution.A total of 139 clones were derived from 13 parent hybrid cultures. To date, four of these cloned cultures have been propagated as ascitic tumours in mice. The preparation of IgG from ascitic fluid and labelling of this antibody with 125I is described. Results indicate that the use of labelled monoclonal antibodies as indicator reagents in solid-phase IgM antibody capture assays for the detection of rubella-specific IgM results in enhanced performance of these tests.

A panel of mouse hybridomas secreting monoclonal antibody to serum hepatitis Be antigen (HBeAg) was produced from mice immunized with denatured hepatitis B core antigen (HBcAg). This panel could be divided broadly into two groups. Within each group, the monoclonal antibodies recognized a single antigenic site, designated either e-alpha or e-beta, and generally exhibited a high degree of cross-inhibition. In contrast, between the two groups of antibodies there was little or no cross-inhibition. The antigens of serum HBeAg and denatured HBcAg appeared to be very similar. Both behaved as molecules carrying only a single e-alpha or e-beta site, in spite of native serum HBeAg having an apparent molecular weight of 300 000. It is inferred that e-alpha and e-beta sites may be involved in the polymerization of HBeAg into HBcAg and that during this process mutual masking of antigenic sites may occur.

SummaryRadial haemolysis (RH) was used to test sera for immunity to rubella from 1317 patients attending a general practice. One hundred and forty-one (10·7%) were treated as susceptible and offered an attenuated virus vaccine (RA 27/3). Pre-immunization sera from 43% of these patients were reactive at low levels in RH (< 15 international units rubella antibody per ml).Pre- (S1) and post- (S2) immunization sera from 66 vaccinees were studied in detail. Antibody was detected by RH, haemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA), and the specific IgM response was measured by a solid-phase M-antibody capture radioimmunoassay (MACRIA). The vaccine-induced IgM response was only detected if the S1 serum was non-reactive by all tests for rubella antibody. It was weaker than that seen following wild virus infection. It could be detected reliably for six weeks, and in most cases for nine weeks, after immunization. In contrast, patients with S1 specimens reactive by RH, HI or ELISA never showed an IgM response in the S2 specimen despite ‘significant’ antibody rises often being present.It was considered that an IgM response to RA 27/3 was the best indicator of pre-immunization susceptibility to rubella. The failure of many vaccinees to make an IgM response implied that a significant proportion were already immune. It is suggested that the threshold for a report of immunity to rubella could be lowered from 15 i.u. antibody per ml and so fewer women immunized without vaccine being withheld from those who need it.

SUMMARYAn M-antibody capture radioimmunoassay (MACRIA) for anti-rubella IgM was developed. Under optimum conditions positive serum specimens bound up to 20 times as much radioactivity as negative specimens. Positive reactions were expressed in arbitrary units/ml by comparison with a calibration curve derived from results obtained with dilutions of a standard serum.The specificity of the assay was confirmed by testing IgM and IgG rich fractions of positive sera. One hundred and forty specimens from blood donors, patients whose sera contained rheumatoid factor and patients with acute, non-rubella, virus infections were tested by MACRIA. No significant non-specific reactions were detected.Paired sera from acute rubella (25 patients) and individual sera from suspected rubella (69 patients) were tested for anti-rubella IgM by MACRIA and by haemagglutination inhibition following sucrose-density-gradient fractionation. There was close agreement between the two methods. The capture assay was more sensitive and could be used to detect the weak IgM response in women given RA 27/3 vaccine. After the natural infection, the MACRIA was strongly positive for two months and remained weakly so for a further two months. Repeat testing of sera demonstrated good reproducibility of the assay.MACRIA proved a simple, sensitive and specific test for anti-rubella IgM and compared favourably with currently used techniques.