Indirect ELISA for the detection of HSV-2 specific IgG and IgM antibodies with glycoprotein G (gG-2)

The glycoprotein G (gG-2) purified from HSV-2 infected cells has been reported to be useful for determination of HSV-2 type-specific antibodies using conventional ELISA formats. This study further confirmed the specificity of gG-2 and demonstrated the feasibility of a specific IgM assay. The gG-2 ELISA was developed to detect HSV-2 specific IgG and IgM antibodies in human sera with high levels of sensitivity and specificity. Of 45 patients with culture-proven recurrent HSV-2 genital infection 44 were reactive for gG-2 IgG. Of 30 sera from patients with culture-proven recent initial HSV-2 genital infection 29 were positive for gG-2 IgM. Three patients with primary HSV-2 genital infection showed gG-2 IgM in the convalescent but not in the acute sera. The IgG- and IgM-gG-2 ELISA showed high specificity. None of 40 sera from children were reactive by either assay. Only one of 94 sera from patients with antibody to herpesviruses other than HSV reacted in the IgG assay but none reacted in the IgM assay. There was no cross-reaction with sera from patients with proven HSV-1 infection with the gG-2 antigen. The results suggest that the IgG assay can be used for demonstration of past HSV-2 infection and the IgM assay for the diagnosis of HSV-2 in neonatal herpes and primary genital herpes, when cultures or rapid diagnostic techniques are unavailable.

HIV infection of monocytes inhibits the T-lymphocyte proliferative response to recall antigens, via production of eicosanoids

Human monocytes infected in vitro with human immunodeficiency virus (HIV) soon after adherence to plastic substrate demonstrated a significantly decreased ability to restimulate autologous immune T-lymphocyte proliferation after exposure to soluble (tetanus toxoid) and particulate [herpes simplex virus (HSV)] antigen. Incubation with the cyclo-oxygenase inhibitor, indomethacin (2-5 microM), prevented inhibition of antigen-stimulated lymphocyte proliferation. The inhibitory activity was identified in ultrafiltrates containing the low molecular weight fraction (less than 3000 MW) of supernatants from HIV-infected monocyte cultures. This activity was significantly and markedly reduced in similar ultrafiltrates prepared from indomethacin-treated cultures. Increased concentrations of prostaglandin E2 (PGE2) were detected in ultrafiltrates from HIV-infected monocyte cultures compared with uninfected cultures and cultures preincubated with indomethacin. Ultrafiltrates were inhibitory when added during the presentation of antigen to T lymphocytes but not when removed from monocyte cultures prior to the addition of lymphocytes. In addition, ultrafiltrates inhibited antigen-stimulated lymphocyte proliferation and PHA-induced lymphocyte proliferation to the same extent. These data indicate that cyclo-oxygenase products of arachidonic acid, including PGE2, are produced in excess by HIV-infected monocytes and that PGE2 and perhaps other cyclo-oxygenase products are implicated in the inhibition of antigen-stimulated lymphocyte proliferation via a direct effect on T lymphocytes.

Nonspecific proctitis: association with human immunodeficiency virus infection in homosexual men

In a cross-sectional study of 140 homosexual men attending a sexually transmissible diseases clinic, the association between the presence of antibody to the human immunodeficiency virus (HIV) and the presence of proctitis, as determined by histologic examination, as well as part or present exposure to other pathogens and details of sexual practices was analyzed. Significant associations with HIV seropositivity were found with the number of lifetime partners, positive treponemal serology, and evidence of previous infection with herpes simplex virus. However the major and unique finding was the strong and independent association between proctitis diagnosed by histologic criteria and seropositivity for HIV. Whether this is cause or effect awaits further elucidation.

The validity of parental report of vaccination as a measure of a child's measles immunisation status

OBJECTIVE

To determine the validity of parental report of vaccination as a measure of a child's measles immunisation status.

DESIGN

Cross-sectional survey.

SETTING

Four 24-hour medical centres in western Sydney.

PATIENTS

Parents of children aged 12-36 months were approached in the clinic waiting room. Of the 160 parents approached, 137 agreed to be interviewed and a successful venepuncture to yield a 2 mL blood sample was achieved with 128 children.

MAIN OUTCOME MEASURES

Measles IgG antibody, determined by means of an indirect ELISA, was compared with parental report of measles vaccination status by McNemar's chi 2 test.

RESULTS

Parental report significantly over-estimates the immunisation status of children. Eighty-four per cent of the parents in the sample stated that their child had been vaccinated, but only 74% were immune (95% confidence interval, 65%-81%). A positive predictive value of 84% meant that only 84% of children who were reported to have been vaccinated were immune to measles. Further, of all those who were not immune to measles, only one half would have been identified by asking the parents. Failed seroconversion may have accounted for up to 70% of cases of non-immunity in children reported to have been vaccinated.

CONCLUSIONS

Parental report is limited as a measure of a child's measles immunisation status.

Influenza A(H1N1): a widening spectrum?

OBJECTIVE

To study the incidence of H1N1 influenza from 1977 to 1988 in unvaccinated volunteers and the effects of continuing minor antigenic change (antigenic drift) in the virus.

DESIGN

Prospective study by a group of general practitioners, backed up by virological findings.

PARTICIPANTS

Mainly patients of the general practitioner group, also some doctors and members of staff. There were 287 participants during 1977-1981, and 207 at the end of 1988.

INTERVENTION

Any participant deemed to be "at risk" was encouraged to be vaccinated and to withdraw from the study.

BACKGROUND

In 1957, H1N1 subtype influenza had been displaced by H2N2 (Asian) subtype. In 1968, H2N2 was displaced by H3N2 (Hong Kong) subtype. During 1977, H1N1 influenza unexpectedly reappeared in Asia, and spread widely. The resurgent strain, designated A/USSR/90/77(H1N1), caused world pandemics, attacking (almost exclusively) persons who had been born since the 1950-1951 northern winter and causing negligible mortality. It did not displace the current H3N2 strain, and strains of both subtypes have continued to emerge independently.

HYPOTHESIS

Antigens of A/USSR resembled closely those of the 1950-1951 H1N1 strain, which apparently was rendered antigenically inert between 1951 and 1976 (possibly frozen) and was reactivated during 1977. Antigenic drift was then resumed.

MAIN OUTCOME MEASURE

The A/USSR/90/77 strain and its close successor, A/Brazil/11/78, attacked mainly the young, whose previous exposure to H1N1 antigens had been minimal or zero. Mortality during the A/USSR pandemics was negligible because death from influenza in people aged less than 30 years is rare. Would continuing antigenic drift ultimately widen the H1N1 spectrum of attack?

RESULT

During the epidemic of 1988, A/Taiwan/1/86(H1N1) attacked a wider range of age groups than had A/USSR or A/Brazil.

CONCLUSION

Assuming that H1N1 viruses continue to undergo further antigenic drift, an ever widening age spectrum of H1N1 attack may be expected.

Contralateral hemiplegia following thoracic herpes zoster

OBJECTIVE

To suggest interim therapeutic guidelines for stroke following truncal herpes zoster on the basis of the first reported Australian case, in a patient who showed good clinical response related temporally to antiviral therapy.

CLINICAL FEATURES

A 70-year-old patient with no known underlying immune disorder presented with left-sided hemiplegia one week after right-sided truncal herpes zoster. In all probability the neurological deficit was due to large artery vasculopathy with thrombosis.

INTERVENTION AND OUTCOME

Clinical improvement (not to pre-morbid levels) was noted soon after commencement of antiviral therapy with acyclovir.

CONCLUSION

Stroke following herpes zoster may be a treatable condition. In view of the previously described occurrence of viral antigen within the walls of intracerebral vessels, the occasional progression of the syndrome over months, the generally low toxicity of acyclovir and the clinical response of the few patients treated with antiviral agents to date, early antiviral therapy in patients presenting with delayed contralateral hemiplegia associated with herpes zoster is recommended as prudent.

Roseola infantum and other syndromes associated with acute HHV6 infection

Eight cases of acute human herpesvirus type 6 (HHV6) infection in infants were diagnosed serologically by the demonstration of IgM anti-HHV6 (8/8) and a significant change in total anti-HHV6 antibody titre (6/8). Four infants were sufficiently ill to require admission to hospital and further investigations: one with encephalitis and three with gross hepatosplenomegaly, two of whom had evidence of simultaneous infection with another herpes-virus. The remaining four infants had an illness compatible with roseola infantum, although this diagnosis had not been made clinically. Sera from two of those infants with rash had been sent for analysis to exclude rubella because the infants' mothers were pregnant. The other two had received antibiotics when febrile, and the subsequent appearance of the roseola rash had raised the possibility of antibiotic allergy. The data suggest that there are clinical syndromes in addition to roseola infantum associated with the presence of IgM anti-HHV6, in which serological screening for evidence of acute HHV6 infection may be useful.

Does hepatitis C virus play a role in "non-viral" chronic liver disease?

It has recently been suggested that the hepatitis C virus may play a significant role in chronic liver diseases, such as autoimmune chronic active hepatitis, which are usually attributed to non-viral causes. We tested for antibodies to hepatitis C virus (anti-HCV) in sera from 140 patients with well characterised "non-viral" chronic liver diseases as well as sera from 51 patients thought to have chronic non-A, non-B (NANB) hepatitis (acting as positive controls) and 25 patients with non-hepatic autoimmune disorders. As expected, 45 of 51 patients (88%) diagnosed as having chronic NANB hepatitis were anti-HCV seropositive. Among 26 patients with cryptogenic cirrhosis, 8 were anti-HCV seropositive; in 5 patients (22%) there was no apparent risk factor for parenteral transmission. In the remaining 114 patients with chronic liver disease, 10 patients (9%) were seropositive for anti-HCV. However, 5 of these patients had a significant risk factor for parenteral transmission of hepatitis C virus, leaving only 5 of 106 (4.7%) with unexplained positive anti-HCV test results. Among patients with high titres of circulating autoantibodies but no liver disease, no positive results occurred. It is concluded that hepatitis C virus infection may account for some cases of cryptogenic cirrhosis. Although anti-HCV occurs more commonly in patients with other "non-viral" chronic liver diseases than has been reported in the community (0.5%-1.2%), the low prevalence of the antibodies indicates that hepatitis C virus infection is unlikely to be important in the aetiology or pathogenesis of autoimmune chronic active hepatitis and other poorly understood chronic liver diseases.

Hepatitis C virus in intravenous drug users

Sera from 172 intravenous drug users were tested for the presence of antibodies to hepatitis C virus (anti-HCV). The results were analysed in relation to aspects of the history of drug use and evidence of liver disease. The presence of anti-HCV was strongly associated with duration of intravenous drug use. Two-thirds of patients were anti-HCV seropositive within two years of commencing regular intravenous drug use, and there was 100% seropositivity among people injecting drugs for more than eight years. Seropositivity for hepatitis C virus closely paralleled exposure to hepatitis B virus, which was also endemic in this population. In contrast, only one patient tested positive for antibodies to the human immunodeficiency virus. The presence of anti-HCV correlated poorly with biochemical markers of hepatitis. About half the patients with anti-HCV had normal serum levels of alanine aminotransferase, whereas an abnormal liver biochemistry was frequently observed in anti-HCV seronegative subjects. Previous studies of non-A, non-B hepatitis that have used abnormal liver biochemistry as a marker have underestimated the prevalence of chronic hepatitis among intravenous drug users; the use of a specific screening test reveals that infection with hepatitis C virus is very common in this population.

A polyanion binding site on the CD4 molecule. Proximity to the HIV-gp120 binding region

Recent studies have demonstrated that sulfated polyanions (SP) are potent inhibitors of HIV infection in vitro, appearing to inhibit virus attachment. To understand the mode of action of these compounds a large panel of SP were examined for their ability to inhibit HIV infection, block anti-CD4 mAb binding and, when immobilized, bind soluble CD4 and virion gp120. Based on anti-CD4 mAb binding-inhibition studies a SP binding site was identified on the CD4 molecule. Dextran sulfate (DXS)-500 kDa, polyvinylsulfate (PVS), and polyanethole sulfonate were particularly potent SP inhibitors, blocking the binding of 11 of the 12 anti-CD4 mAb tested. These 11 mAb are known to interact with the two amino-terminal Ig-like domains of CD4. In fact, DXS-500 kDa exhibited an hierarchy of inhibition of anti-CD4 mAb which suggests that SP bind to a conformational site incorporating the first two Ig-like domains of CD4. This SP binding site is clearly distinct but closely associated with the gp120 binding region of CD4. In terms of anti-HIV activity there was no evidence that SP act at the virion level as rgp120 did not bind to immobilized SP and preincubation of virions with SP did not affect infectivity. In contrast, many of the SP tested showed some affinity for CD4 based on anti-CD4 mAb blocking studies and binding of soluble CD4 to immobilized SP. The most active in this regard were DXS-500 kDa and PVS, whose anti-HIV activity could be entirely due to disruption of the CD4-gp120 interaction. However, with SP such as heparin, fucoidan, the carrageenans, and polyanethole sulfonate, although CD4 blocking may contribute to anti-HIV activity, some other anti-viral mechanism is also operating. Finally, pentosan sulfate, a SP with anti-HIV activity comparable to DXS-500 kDa and PVS, showed little or no reactivity with CD4 and must inhibit HIV infection by a totally CD4-independent mechanism.

A polyanion binding site on the CD4 molecule. Proximity to the HIV-gp120 binding region

Recent studies have demonstrated that sulfated polyanions (SP) are potent inhibitors of HIV infection in vitro, appearing to inhibit virus attachment. To understand the mode of action of these compounds a large panel of SP were examined for their ability to inhibit HIV infection, block anti-CD4 mAb binding and, when immobilized, bind soluble CD4 and virion gp120. Based on anti-CD4 mAb binding-inhibition studies a SP binding site was identified on the CD4 molecule. Dextran sulfate (DXS)-500 kDa, polyvinylsulfate (PVS), and polyanethole sulfonate were particularly potent SP inhibitors, blocking the binding of 11 of the 12 anti-CD4 mAb tested. These 11 mAb are known to interact with the two amino-terminal Ig-like domains of CD4. In fact, DXS-500 kDa exhibited an hierarchy of inhibition of anti-CD4 mAb which suggests that SP bind to a conformational site incorporating the first two Ig-like domains of CD4. This SP binding site is clearly distinct but closely associated with the gp120 binding region of CD4. In terms of anti-HIV activity there was no evidence that SP act at the virion level as rgp120 did not bind to immobilized SP and preincubation of virions with SP did not affect infectivity. In contrast, many of the SP tested showed some affinity for CD4 based on anti-CD4 mAb blocking studies and binding of soluble CD4 to immobilized SP. The most active in this regard were DXS-500 kDa and PVS, whose anti-HIV activity could be entirely due to disruption of the CD4-gp120 interaction. However, with SP such as heparin, fucoidan, the carrageenans, and polyanethole sulfonate, although CD4 blocking may contribute to anti-HIV activity, some other anti-viral mechanism is also operating. Finally, pentosan sulfate, a SP with anti-HIV activity comparable to DXS-500 kDa and PVS, showed little or no reactivity with CD4 and must inhibit HIV infection by a totally CD4-independent mechanism.

Dual antibody rises to cytomegalovirus and human herpesvirus type 6: frequency of occurrence in CMV infections and evidence for genuine reactivity to both viruses

The frequency of high (greater than 256) IgG anti-human herpesvirus type 6 (HHV-6) titers in sera known to be positive for IgM anti-cytomegalovirus (CMV) or IgM anti-Epstein Barr virus (EBV) was significantly greater than in sera from healthy controls or from a group of ill patients who were CMV and EBV IgM-negative (15/25 and 17/25 vs. 1/25 and 2/25, respectively, P less than .001). There was serologic evidence of simultaneous HHV-6 infection or reactivation (a rise in IgG anti-HHV-6 titer or the presence of IgM anti-HHV-6) in sera from 14 of 17 primary CMV infections. In 5 of the 10 patients with concurrent rises in IgG titers to both viruses, the rise in IgG anti-HHV-6 preceded that of IgG anti-CMV. Complete removal of IgG anti-CMV reactivity from 5 sera from patients who had a primary CMV infection with a rise in IgG anti-HHV-6 titer had no effect on the IgG anti-HHV-6 titer of those sera, demonstrating that the rise in HHV-6 IgG titer was not a consequence of anti-CMV antibodies cross-reacting in the HHV-6 IgG assay.

Serological diagnosis of infection with human herpesvirus type 6

OBJECTIVE

To identify clinical consequences of acute human herpesvirus type 6 infection by hypothesising that the virus will induce similar clinical syndromes to cytomegalovirus.

DESIGN

Examination of consecutive serum samples from patients with illnesses compatible with acute cytomegalovirus infection or exanthem subitum by indirect immunofluorescence for the presence of antibodies to human herpesvirus type 6. An IgG absorption step was included to avoid false positive and negative results for IgM. The criterion standard for diagnosis of human herpesvirus type 6 infection was the presence of IgM human herpesvirus type 6 antibody (titre greater than 20) and a rising titre of IgG human herpesvirus type 6 antibody without serological evidence of alternative infection.

SETTING

Routine viral diagnostic and reference laboratory in the largest teaching hospital in Sydney.

PATIENTS

341 Consecutive serum samples were analysed from patients with hepatitis (147 samples); infectious mononucleosis-like illness (106); screens for toxoplasma, other viruses, rubella, cytomegalovirus, and herpesvirus (38); fever in an immunocompromised patient (eight); unusual neurological (nine) or haematological syndromes (14); splenomegaly (six); and rash in a child (13).

RESULTS

Three cases of acute human herpesvirus type 6 infection were identified: in one patient aged 65 with a previous diagnosis of acute non-A non-B hepatitis, one aged 25 with a glandular fever-like illness, and one aged 6 with a glandular fever-like illness. All three illnesses resolved completely. 15 Further serum samples were positive for human herpesvirus type 6 antibody but were also diagnostic for acute infection with other viruses (cytomegalovirus (nine), Epstein-Barr virus (three), and HIV (one] or had a titre of IgM human herpesvirus type 6 antibody less than 20 (two).

CONCLUSIONS

Acute human herpesvirus type 6 infection in immunocompetent patients may result in a mononucleosis-like illness or an acute but self limiting hepatitis.

HIV-1 antibody testing strategy: evaluation of ELISA screening and western blot profiles in a mixed low risk/high risk patient population

The Westmead HIV-1 antibody testing strategy showed that, regardless of ELISA screening kit manufacturer, sera which were repeatedly positive by two ELISA screening assays (one indirect and the other competitive format) had a 97-98% chance of being confirmed positive by Western blot for HIV-1 antibody or a less than 3% chance of either being identified as a seroconverter (1%) or a late stage AIDS patient (1.2%). Sera which were discordant by two ELISA screening assays had a less than 4% chance of either being confirmed positive by Western blot (2.5%) or identified as a seroconverter (1.3%). The incidence of non-specific indeterminate Western blot profiles were shown to be inversely proportional to the specificity of the ELISA screening kits used. The use of a recombinant envelope ELISA was able to confirm the viral specificity of HIV-1 envelope bands (gp160, 120 or 41) on Western blot. Guidelines suggested by the Australian National HIV Reference Laboratory, Fairfield Hospital, Melbourne, which categorized indeterminate or typical Western blot profiles into four reaction groups were found to be useful for the interpretation of Western blot patterns. A Western blot profile which is reactive for HIV-1 viral glycoproteins (gp160, 120 and 41) alone or in combination with not more than two other viral proteins (Indeterminate Group 4) and which is confirmed viral envelope specific by a recombinant envelope ELISA can be used as a predictor of seroconversion.

Variations in CD4 expression by human monocytes and macrophages and their relationships to infection with the human immunodeficiency virus

The expression of CD4 antigen on the surface of LeuM3-positive human blood monocytes was found to be variable with 65 to 90% of cells from 46 normal human volunteers being positive by dual staining flow cytometry. When monocytes adhered to plastic (but not when cultured on Teflon), a marked decrease in CD4 expression was observed between 1 and 24 h post-adherence. CD4 expression could not be detected in macrophages adhered to plastic for 5 days by using four anti-CD4 monoclonal antibodies in flow cytometry or direct immunofluorescence. Conversely an increasing proportion of adherent cells expressed LeuM3 and OKM5 surface antigens over the 5 days. CD4 mRNA levels were measured by slot-blot and Northern hybridization, and total cellular CD4 protein levels by immunoprecipitation. Both cellular mRNA and CD4 levels remained constant throughout the 5 day period but membrane CD4 protein levels were greatly reduced indicating that the down-regulation of CD4 was post-translational. Infection with two of six fresh human immunodeficiency virus (HIV) isolates showed different kinetic patterns when tested on purified monocytes recently adhered to plastic and macrophages adherent for 5 days. HIV antigen and reverse transcriptase levels in infected monocyte cultures remained high for 3 to 4 weeks before detachment and necrosis of the cells occurred. Infection of macrophages generated much lower levels of antigen and reverse transcriptase which declined to very low or undetectable levels over 2 weeks, leaving persisting viable macrophages. One week after infection HIV nucleic acid was detected in 69 +/- 7% of monocytes and 6 +/- 3% of macrophages by in situ hybridization. Blocking experiments with anti-Leu3a monoclonal antibody suggested that HIV infection of 5 day adherent macrophages occurred mainly by a mechanism other than binding to CD4.

Rapid diagnosis of acute Epstein-Barr virus infection by an indirect enzyme-linked immunosorbent assay for specific immunoglobulin M (IgM) antibody without rheumatoid factor and specific IgG interference

An indirect enzyme-linked immunosorbent assay (ELISA) for detection of Epstein-Barr virus-specific immunoglobulin M (IgM) antibody was developed with commercial reagents. Sera containing rheumatoid factor (RF) (as little as 0.5 IU/ml) coupled with specific IgG resulted in false-positives in the ELISA. This interference was eliminated by the use of anti-human IgG antibodies to remove RF and IgG. Thus, pathogen-specific IgG complexes to which IgM-RF could be bound during the subsequent test were inhibited, and competition between specific IgG and IgM was also prevented. Of the 1,672 serum specimens tested, 353 were found to be Epstein-Barr virus IgM antibody positive by indirect immunofluorescence (IF). Compared with the IF test, the ELISA showed 96.6% sensitivity, 99.7% specificity, and 99% accuracy. Further evidence indicated that most of the 12 ELISA false-negatives were IF false-positives. There was a linear correlation between mean ELISA values and increasing IF titers (r = 0.96). However, the IF test has the disadvantages that it lacks automated reading and requires considerable technical expertise, both of which restrict the range of laboratories performing the test. The indirect ELISA has the advantages that it is simple and rapid and can be automated. All the reagents used in this assay are commercially available, have been prestandardized, and are stable.

Role of keratinocytes in human recurrent herpetic lesions. Ability to present herpes simplex virus antigen and act as targets for T lymphocyte cytotoxicity in vitro

In human recurrent herpetic lesions epidermal keratinocytes are induced to express HLA class II (DR) antigens. Keratinocytes derived from human split skin and cultured in vitro were induced to express HLA-DR but not -DQ antigens with IFN gamma preparations. These stimulated keratinocytes presented herpes simplex antigen directly to autologous blood-derived T lymphocytes in four of four subjects (stimulation indices: 1.5-2.7), suggesting that keratinocytes may have an accessory herpes simplex virus (HSV) antigen-presenting role in addition to the Langerhans cells and macrophages in herpetic skin lesions. Blood mononuclear cells from eight herpes simplex seropositive subjects which were activated in vitro by HSV antigen for 6 d showed cytotoxicity specific for HSV in infected autologous keratinocytes. This was significantly increased by prestimulation with IFN gamma (51-56% to 83-85%). In four of eight patients some cytotoxicity also occurred against uninfected, IFN gamma-stimulated keratinocytes. Lymphocyte subset analysis showed that cytotoxicity against HSV-infected, IFN gamma-stimulated keratinocyte targets was mediated by both CD3+ T lymphocytes and Leu 11b+ natural killer cells. T lymphocyte cytotoxicity was mediated by both CD4+ and CD8+ T lymphocytes, suggesting a cytotoxic role for the activated CD4+ lymphocytes that initially predominate in herpetic lesions.

Should all pregnant women be screened for hepatitis B surface antigen?

One thousand, one hundred and ninety-three pregnant women were screened for hepatitis B surface antigen (HBsAg) carriage after their histories had been reviewed to assess their risk status. In this prospective study, carrier rates were examined according to conventional risk criteria and also according to extended criteria that included the country of birth of the patient's parents. Twenty-six (2.2%) patients were found to be HBsAg seropositive, and one of these patients showed no identifiable risk factors. In four hepatitis B virus carriers, the only risk factor was that the patients' parents had been born in a country that was classified as high risk. Thus, five (19%) of 26 patients would not have been identified by means of previously-accepted screening procedures. Four hundred and forty-two (37%) patients showed at least one conventional risk factor and 558 (47%) patients showed at least one risk factor by our extended criteria. Given the high costs to the community of chronic hepatitis B virus carriage, it was concluded that the screening of all antenatal clinic patients for the presence of HBsAg is cost effective.