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PubMed1995

Factors associated with progression to AIDS and mortality in a cohort of HIV-infected patients with hemophilia followed up since seroconversion.

Progression to AIDS and death were evaluated in 112 patients, 84 with hemophilia A and 28 with hemophilia B. Seroconversion period and age at seroconversion were similar in both groups. 36/112 patients died: 21/84 with hemophilia A (25%) and 15/28 (54%) with hemophilia B. Mean survival time was 11.7 years. The 10-year cumulative survival was 75.8%. It was lower in hemophilia B (56.2%) compared to hemophilia A patients (82.4%; p = 0.002). 37 patients (33%) developed full-blown AIDS: 26 with hemophilia A (31%) and 11 with hemophilia B (39%). Mean AIDS-free survival time was 11.4 years. The 10-year cumulative AIDS-free survival was 71.2%. It was 74.8% in hemophilia A and 60.3% in hemophilia B patients. CD4 counts lower than 200/cmm occurred in 62 patients (56%): 45 with hemophilia A (54%) and 17 with hemophilia B (63%). The mean time to CD4 counts lower than 200 was 9.4 years. Mean survival time in older seroconverters (35 year old or more) was shorter than in younger (9.5 vs. 11.7 years, p < 0.05). Mean CD4 cell counts at seroconversion were similar in hemophilia A and B patients and in different age classes at seroconversion. CD4 cell counts at seroconversion affected the survival: 90% seroconverters with CD4 cell counts of 800/cmm or more were alive at 10 years vs. 60% of seroconverters with CD4 cell counts lower than 800 (p < 0.05).

Acquired Immunodeficiency Syndrome↗

PubMed1993

Seroconversion to Cowdria ruminantium of Malawi zebu calves, reared under different tick control strategies.

The seroconversion by indirect ELISA to Cowdria ruminantium over the first year of life of sixty-six Malawi zebu calves born into groups which were dipped 17 times per year was compared to seroconversion of 32 calves born into non-dipped groups. Amblyomma variegatum tick counts and clinical disease in each group of cattle were monitored throughout the study period. No cases of heartwater were seen in either group of calves over the first 22 months of life. Only one case of heartwater was observed, in an 8 year old cow, in the 1,800 intensively monitored cattle over the same period. By 12 months of age almost all undipped calves had seroconverted and 50% of seroconversions were attributed to nymphal challenge. In contrast, only 41% of calves had become seropositive by 12 months of age in the dipped groups. The dipping regime used therefore significantly decreased seroconversion rates to C. ruminantium in these calves. 73% of calves had detectable levels of maternal antibodies to C. ruminantium in the first 4 weeks of life. Antibody levels in each of the calves in dipped groups had waned to below the cut off point for the ELISA by 8-12 weeks. Seroconversion did not occur in the first 8-12 weeks of life in dipped herds. The indirect ELISA test results were not significantly different in the proportion positive in single tests at 12 months of age, or by cumulative test results of the previous 9 months, and therefore the test may be of value as a test of herd immunity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2007

Temporal trends in postseroconversion CD4 cell count and HIV load: the Concerted Action on Seroconversion to AIDS and Death in Europe Collaboration, 1985-2002.

OBJECTIVE: To determine whether early postseroconversion CD4 cell counts and human immunodeficiency virus (HIV) loads have changed over time. METHODS: Our analysis was based on 22 cohorts of people with known dates of seroconversion from Europe, Australia, and Canada (Concerted Action on Seroconversion to AIDS and Death in Europe Collaboration). We focused on individuals seroconverting between 1985 and 2002 who had the first CD4 cell count (n=3687) or HIV load (n=1584) measured within 2 years of seroconversion and before antiretroviral use. Linear regression models were used to assess time trends in postseroconversion CD4 cell count and HIV load. Trends in time to key thresholds were also assessed, using survival analysis. RESULTS: The overall median initial CD4 cell count was 570 cells/ microL (interquartile range [IQR], 413-780 cells/ microL). The median initial HIV load was 35,542 copies/mL (IQR, 7600-153,050 copies/mL; on log(10) scale, 3.9-5.2 log(10) copies/mL). The postseroconversion CD4 cell count changed by an average of -6.33 cells/ microL/year (95% confidence interval [CI], -8.47 to -4.20 cells/ microL/year; P<.001), whereas an increase was observed in log(10) HIV load (+0.044 log(10) copies/mL/year; 95% CI, +0.034 to +0.053 log(10) copies/mL/year). These trends remained after adjusting for potential confounders. The probability of progressing to a CD4 cell count of <500 cells/ microL by 24 months from seroconversion increased from 0.66 (95% CI, 0.63-0.69) for individuals who seroconverted before 1991 to 0.80 (95% CI, 0.75-0.84) for those who seroconverted during 1999-2002. CONCLUSION: These data suggest that, in Europe, there has been a trend of decrease in the early CD4 cell count and of increase in the early HIV load. Additional research will be necessary to determine whether similar trends exist in other geographical areas.

Adult↗

PubMed1996

HIV seroincidence and correlates of seroconversion in a cohort of male factory workers in Harare, Zimbabwe.

OBJECTIVES: Given that health promotion messages on transmission of HIV and other sexually transmitted diseases (STD) have been widely publicized in Zimbabwe and elsewhere in the late 1980s, it is vital to analyse which risk events still expose individuals to infection. A cohort was established with the objectives of estimating HIV seroincidence, behavioural and biological determinants of infection, and ultimately, evaluating the impact of AIDS prevention interventions in the workplace. METHODS: HIV seroincidence was estimated in a prospectively followed cohort of male factory workers recruited in Harare, Zimbabwe during the period prior to a workplace AIDS prevention intervention. Correlates of HIV seroconversion were identified using Cox regression analysis. RESULTS: There were 51 seroconversions among 1607 HIV-negative participants following 1738 person-years (PY) of observation [seroincidence, 2.93 per 100 PY; 95% confidence interval (CI), 2.18-3.86]. The prevalence of HIV in the cohort was 19.1%. HIV seroincidence was significantly increased among men who were younger [hazard ratio (HR) per year, 0.96; 95% CI, 0.93-0.99], were single (HR, 3.29; 95% CI, 1.56-6.96), were married but resided separately from their wives (HR, 2.18; 95% CI, 0.99-4.80), reported having any STD (HR, 3.00; 95% CI, 1.53-5.86), reported having a genital ulcer (HR, 4.87; 95% CI, 2.18-10.91), and reported paying for sex (HR, 2.01; 95% CI, 1.06-3.77). Seroincidence also increased with the number of sex partners reported in the year preceding enrolment (HR per partner, 1.10; 95% CI, 1.01-1.21). In multiple Cox regression analysis, three independent associations with HIV seroconversion were reporting a genital ulcer (adjusted HR, 3.55; 95% CI, 1.52-8.29), number of sex partners (adjusted HR, 1.10; 95% CI, 1.01-1.21), and being married but residing separately from one's wife (adjusted HR, 2.21; 95% CI, 1.00-4.89). CONCLUSIONS: Innovative and sustained workplace-based interventions are needed to address the high risk of HIV infection in this economically productive population. The predictors of HIV seroconversion described in this study underscore the need for public health efforts to simultaneously address the biological, socioeconomic and behavioural factors that continue to place individuals at risk of HIV in general populations of Africa.

Acquired Immunodeficiency Syndrome↗

PubMed2003

Prediction of incident neurocognitive impairment by plasma HIV RNA and CD4 levels early after HIV seroconversion.

BACKGROUND: Neuropsychological (NP) impairment is a relatively common sequela in human immunodeficiency virus (HIV)-infected individuals with advanced disease. Early antecedents of NP dysfunction, however, remain poorly understood. OBJECTIVE: To determine whether early markers of immunocompetence and viral replication in individuals who have undergone seroconversion would be of prognostic value in identifying subjects who would become cognitively impaired. METHODS: Seventy-four subjects with estimable seroconversion dates and normal cognition at baseline (a median of 1 year after seroconversion) received NP and laboratory evaluations, including reverse transcription-polymerase chain reaction measurements of plasma (N = 74) and cerebrospinal fluid (n = 47) levels of HIV RNA. Subjects were followed up longitudinally, and were considered to have reached the end point if they became cognitively impaired. RESULTS: Using Kaplan-Meier estimates, the subgroups with the most rapid progression to NP impairment were (1) subjects with early reductions in CD4 counts (<400 cells/microL at baseline; P =.007) and (2) those with elevated plasma HIV RNA values (>4.5 log10 copies/mL; P =.03) early after seroconversion. Using proportional hazards modeling, the highest-risk subjects had both CD4 counts less than 400 cells/microL and HIV RNA levels greater than 4.5 log10 copies/mL (risk ratio, 6.0; P =.01). In most subjects (7/9 [78%]), NP impairment developed before an acquired immunodeficiency syndrome-defining illness. CONCLUSIONS: Neurocognitive outcomes in HIV are strongly influenced by very early systemic virological and immunological events. Patients with high plasma levels of HIV RNA and low CD4 counts early after infection should be aggressively treated to prevent immunological decline and NP deterioration.

Adult↗

PubMed2000

Hepatitis B e antigen seroconversion: effects of lamivudine alone or in combination with interferon alpha.

Seroconversion of hepatitis B e antigen (HBeAg) is an important marker for resolution of active hepatitis B virus (HBV) infection and for a long-term positive response to treatment. Lamivudine, a nucleoside analogue, is the first effective oral treatment for chronic hepatitis B in patients with evidence of viral replication and liver disease. When appropriate patient groups are compared, treatment with lamivudine for 1 year leads to HBeAg seroconversion in a similar proportion of patients as a standard course of interferon (IFN) alpha therapy. Seroconversion increases during prolonged therapy (up to 3 years), and is sustained post-treatment in more than three-quarters of patients. Response rates are related to the pretreatment level of serum alanine aminotransferase (ALT) and reach 65% in those patients with serum ALT > 5 x upper limit of normal (ULN) after one year. For patients with pretreatment ALT > 2 x ULN, response was seen in 38% after one year, rising to 65% after 3 years. To date, combination with IFN and lamivudine has not been shown to confer additional benefit compared with lamivudine monotherapy. Lamivudine is effective and appropriate for use in a greater proportion of HBV infected patients than IFN alpha, particularly those infected at birth or in early childhood. Furthermore, because seroconversion after lamivudine is not normally associated with a severe flare of liver disease, as seen with IFN, it is more suitable for use in patients with active liver disease and cirrhosis. In conclusion, lamivudine is more suitable than IFN for a broad range of patients, including those with severe liver disease, recurrent flares, pre-core mutant HBV and those who have failed previously IFN treatment or are immunosuppressed. Lamivudine is also better tolerated than IFN.

Antiviral Agents↗

PubMed2000

Evaluation of antineutrophil cytoplasmic antibody seroconversion induced by minocycline, sulfasalazine, or penicillamine.

OBJECTIVE: Case reports have suggested that minocycline, sulfasalazine, and penicillamine are associated with antineutrophil cytoplasmic antibody (ANCA)-positive vasculitis. This study evaluated ANCA seroconversion due to these agents in serum samples prospectively collected in randomized, double-blind, controlled trials. METHODS: The sources of study sera were 3 clinical trials: 1) a 48-week trial of minocycline for early rheumatoid arthritis, with 64 patients receiving minocycline compared with 68 receiving placebo; 2) a 37-week trial of sulfasalazine for rheumatoid arthritis, with 51 receiving sulfasalazine compared with 38 receiving placebo; and 3) a 104-week trial of penicillamine for early systemic sclerosis, with 15 undergoing high-dose penicillamine treatment versus 12 receiving low-dose penicillamine. ANCA were measured in the baseline and study-end serum samples by indirect immunofluorescence (IIF) for perinuclear ANCA (pANCA) and cytoplasmic ANCA (cANCA) patterns, and by antigen-specific enzyme-linked immunosorbent assay (ELISA) for antibodies to myeloperoxidase (anti-MPO) and proteinase 3 (anti-PR3). Laboratory personnel were blinded to the group identity of the samples. ANCA results were interpreted using an ANCA scoring system that combines the results of IIF and ELISA testing. RESULTS: No patient in any of the active study drug groups demonstrated ANCA seroconversion according to the final interpretation of the combined IIF and ELISA results. Twelve of the 248 patients (5%) were positive for anti-MPO with pANCA at baseline. No subject was positive for anti-PR3 with cANCA. There were no findings suggestive of vasculitis in any of these patients. CONCLUSION: From our study results, there was no suggestion of ANCA seroconversion induced by minocycline, sulfasalazine, or penicillamine. However, these findings do not rule out the possibility of rare, sporadic cases of either ANCA seroconversion or true drug-induced vasculitis with these drugs.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMedDate not supplied

Clinical, virologic and histologic outcome following seroconversion from HBeAg to anti-HBe in chronic hepatitis type B.

Seventy consecutive HBsAg- and HBeAg-positive patients with biopsy-proven chronic hepatitis were followed prospectively with serial determinations of SGPT levels and hepatitis B virus serum markers including HBsAg, HBeAg, anti-HBe and hepatitis B virus DNA. During a period of 1 to 11 years (mean +/- S.D.: 5.0 +/- 2.3 years), 28 patients remained persistently HBeAg positive, most with continuing biochemical and histologic activity, while 41 cases seroconverted to anti-HBe. One patient became HBeAg and anti-HBe negative. After seroconversion, 87.8% of the cases showed sustained normalization of SGPT, and clearance of hepatitis B virus DNA from serum and histologic improvement was documented in 79% of the cases who had a control liver biopsy, while 15.8% developed cirrhosis. In two patients (4.9%), the disease remained active despite seroconversion, and both cases had evidence of continuing hepatitis B virus replication. Finally, reactivation of liver damage and of hepatitis B virus replication was observed in three additional patients (7.3%) who had transiently normalized SGPT after seroconversion. All 70 patients were analyzed for hepatitis delta virus markers, and only two persistently HBeAg-positive cases were found positive for antibody to hepatitis delta virus in serum, one also having hepatitis delta antigen in the liver. These findings indicate that, in chronic hepatitis type B, termination of virus replication is associated in most patients with biochemical and histologic regression of inflammatory activity. After anti-HBe seroconversion has occurred, virus replication and liver disease may persist or reactivate in a small proportion of patients thus giving origin to the well-recognized group of anti-HBe positive, hepatitis B virus DNA-positive chronic hepatitis type B.

Adolescent↗

PubMed1999

Different hepatitis B virus genotypes are associated with different mutations in the core promoter and precore regions during hepatitis B e antigen seroconversion.

Mutations in the core promoter and precore regions are frequently found in hepatitis B e antigen (HBeAg)-negative patients, but precore stop codon mutation is restricted to hepatitis B virus (HBV) genotypes that have T at nucleotide 1858. The aims of this study were to determine the role of core promoter and/or precore mutations in HBeAg seroconversion and their impact on the subsequent course of liver disease, and to determine if core promoter mutations are more frequently selected in patients with HBV genotypes that preclude the development of precore stop codon mutation. Serial sera from 45 patients with chronic HBV infection were polymerase chain reaction (PCR)-amplified, and the HBV core promoter and precore regions were sequenced. Ninety-two percent of patients had core promoter or precore mutations after HBeAg seroconversion: 42% had core promoter changes only, 38% had precore stop codon mutations only, and 12% had changes in both regions. Seventy-three percent of the patients had persistently normal aminotransferases, and only 8% had multiple flares in aminotransferases after HBeAg seroconversion. Core promoter changes were significantly more common in patients infected with HBV who have C at nucleotide 1858 (91% vs. 27%; P <.01), while precore stop codon changes were exclusively found in patients infected with HBV who have T at nucleotide 1858 (87% vs. 0; P <.01). The vast majority of our patients had core promoter and/or precore mutations after HBeAg seroconversion. Nevertheless, most patients had sustained remission of liver disease. Our data suggest that core promoter changes are preferentially selected in patients infected with HBV genotypes that preclude the development of precore stop codon mutation.

Adolescent↗

PubMed1988

HBeAg/anti-HBe seroconversion during and after protracted immunosuppressive treatment in type B chronic hepatitis.

Seventy-seven consecutive HBeAg-positive chronic hepatitis patients were studied from 1971 to 1983 to establish the seroconversion rate in the e system. Patients with less than a year of follow-up were not included in the study. Fifty-six patients with chronic active hepatitis (CAH) received immunosuppressive treatment (corticosteroids combined with azathioprine). The remaining twenty-one patients received no treatment, nine of them with chronic persistent hepatitis (CPH) and 12 with CAH. A retrospective study was performed with stored sera samples: HBeAg and anti-HBe were determined by RIA, and results were correlated with alanine aminotransferase (ALAT) levels in the same samples. The linearized seroconversion rate from HBeAg to anti-HBe was expressed as percent per patient-year. It was 9.6% in CPH patients and 8.8% in CAH patients without treatment. In CAH patients under immunosuppressive drugs it was as low as 1.1% and increased to 28.7% when treatment was withdrawn. ALAT levels were significantly lower in total seroconverted patients when compared with nonseroconverted (NS) patients, but no difference was found between partial seroconverted (PS) and NS patients. The results suggest that although immunosuppressive drug withdrawal may enhance seroconversion rate in type B CAH, delayed seroconversion and reported side effects during treatment stand against protracted usage of these drugs.

Azathioprine↗

PubMed1989

Elimination of circulatory IgM anti-HSA precedes anti-HBe seroconversion in patients with CAH type B.

The presence of IgM and IgA antibodies with specificity for human serum albumin (HSA) were consecutively analyzed in serum samples from four patients with biopsy verified CAH type B during seroconversion in the HBe/anti-HBe antigen system. Circulatory IgM anti-HSA antibodies were present during HBe antigenemia. The antibody titers fluctuated, decreased, and were finally lost from the circulation. After the disappearance of IgM anti-HSA antibodies, seroconversion to anti-HBe reactivity occurred and a quiescent phase of the disease was established, as judged by normalization of transaminases and absence of circulatory HBV-DNA. IgA anti-HSA antibodies persisted in the circulation after the elimination of IgM anti-HSA and seroconversion to anti-HBe reactivity. For one of the patients, a dramatic increase in titers was followed by elimination of IgA anti-HSA and seroconversion to anti-HBs. The data indicate that the host "self"-component HSA, when associated with "foreign" HBe or HBs antigenic structures, elicit immune responses to HSA, preventing the adequate development of anti-HBe and anti-HBs. The cessation of anti-HSA reactivity, however, seemed to permit subsequent sensitization to HBe and HBs antigenic determinants, as detected by the presence of circulatory antibodies.

Adult↗

PubMedDate not supplied

Enhancement in seroconversion to measles vaccine with simultaneous administration of vitamin A in 9-months-old Indian infants.

The mutual interactions of measles vaccine and vitamin A dose when administered simultaneously to 9 month old infants are explored in this study. One hundred healthy infants of 9 months of age received EZ strain of measles vaccine in the routine immunization clinic along with either 100,000 IU of vitamin A or a placebo orally. Blood samples were collected before and 4 weeks after intervention. They were coded and analysed for serum retinol and Hemagglutination Inhibition (HI) antibodies to measles. Ninety five per cent of the infants were seronegative to measles prior to vaccination with a seroconversion rate of 63% in the control group and a significantly higher percent of 83.7% in the experimental group (P < 0.01). Seroconversion was not related to initial serum retinol levels in either of the groups. 42% of infants had serum retinol levels less than 20 ug/dl before administration of the vaccine and both the groups showed improvement in vitamin A status following intervention, the increase being significant in the experimental group (from 22.4 +/- 1.32 to 26.0 +/- 1.07; P < 0.05). The results indicate that majority of the infants at 9 months of age were seronegative to measles. Seroconversion to measles vaccine in the routine immunization clinics was low. Simultaneous administration of vitamin A and measles vaccine had beneficial effects on vitamin A status as well as seroconversion rates to the vaccine in 9 months old infants.

Analysis of Variance↗

PubMed2000

Detection of seroconversion and persistence of Chlamydia trachomatis antibodies in five different serological tests.

Microimmunofluorescence (MIF), a Chlamydia trachomatis species-specific enzyme immunoassay incorporating lipopolysaccharide-extracted Chlamydia trachomatis L2 elementary bodies, two different synthetic peptide-based species-specific tests, and a recombinant lipopolysaccharide genus-specific test were performed on multiple follow-up sera (n = 104 total) from 16 women with Chlamydia trachomatis-positive cervical swabs. These women included five with IgG seroconversions, five with Chlamydia trachomatis reinfections after initial therapy, and six with serologic follow-up of more than 6 years after antibiotic therapy. Of all the tests employed in this study, MIF IgG reverted earliest to negative titers, while MIF IgA was the least sensitive. The lipopolysaccharide-extracted elementary body enzyme immunoassay exhibited the closest correlation with the MIF test. The highest test sensitivity was observed in one of the synthetic peptide-based tests, which detected earliest seroconversions and longest IgG persistence. The other synthetic peptide-based test gave false-negative results in 2 of 16 women and did not detect seroconversion earlier than the MIF test. Seroconversion and persistence of genus-specific IgG--cross-reactivity with Chlamydia pneumoniae--against lipopolysaccharide were similar to species-specific IgG. A significant serologic response to reinfection was observed only in women with signs of pelvic inflammatory disease. Species-specific tests of high sensitivity and reproducibility are best suited for gynecological diagnostic purposes.

Adult↗

PubMed1995

Characterization of HIV infection and seroconversion by a stochastic model of the HIV epidemic.

In this paper we use a stochastic model for the HIV epidemic in homosexual populations to characterize the HIV infection and seroconversion. Using computer generated data, we compare the fitting of infection distributions and of seroconversion distributions by different parametric models as well as by nonparametric methods. The nonparametric methods include the Kaplan-Meier method, EMS method, Bacchetti's method, and the spline approximation. The parametric models include most of the models which have been used in the literature. The comparison criteria are the chi-square statistic, the AIC (Akaike Information Criterion) and the residual sums of squares. The numerical results suggest that for the proportional mixing pattern, the EMS method, the spline method, Bacchetti's method, and the generalized log-logistic distributions with three and with four parameters provide better fitting for the infection and the seroconversion distributions in most cases. For the restricted mixing patterns, the EMS method, the spline method, Bacchetti's method, and some mixtures of distributions provide close fitting to the infection and the seroconversion distributions.

Disease Outbreaks↗

PubMed2004

Natural history of hepatitis B e antigen to antibody seroconversion in patients with normal serum aminotransferase levels.

BACKGROUND: Natural history studies of hepatitis B virus infection have shown relapse of hepatitis in 5% to 15% of patients and progression to cirrhosis in 2% to 6% annually. Follow-up of patients beginning at the early phase of infection might provide data with less referral bias than in previous studies. METHODS: Test of liver biochemistry, assessment of virological markers, and ultrasound examinations were performed at regular intervals during the course of hepatitis B e antigen (HBeAg) to antibody (anti-HBe) seroconversion in 240 HBeAg carriers with normal alanine aminotransferase levels at baseline. Factors predictive of cirrhosis were identified by multivariate analysis. RESULTS: We enrolled 130 men and 110 women. The mean (+/- SD) age at entry was 27.6 +/- 6.2 years. During the HBeAg-positive phase, 29% of patients had alanine aminotransferase levels > or =200 U/L, 3% had bilirubin levels > or =2.0 mg/dL, and 5% had two or more episodes of alanine aminotransferase levels > or =200 U/L. The mean age at anti-HBe seroconversion was 31.3 +/- 7.0 years, with remission of hepatitis in all patients. However, hepatitis recurred in 36 patients (15%), with an annual rate of 2.2%. Thirteen patients (5%) progressed to cirrhosis. The annual incidence of cirrhosis was 0.5%, and the cumulative probability of cirrhosis after 17 years was 12.6%. Age at anti-HBe seroconversion and relapse of hepatitis were independent risk factors for cirrhosis. CONCLUSION: The clinical severity of chronic hepatitis B was milder in this cohort than in previous studies. Delayed HBeAg seroconversion and relapse of hepatitis were associated with increased risk of cirrhosis.

Adolescent↗

PubMed1987

Risk factors for seroconversion to human immunodeficiency virus among male homosexuals. Results from the Multicenter AIDS Cohort Study.

2507 homosexual men who were seronegative for human immunodeficiency virus (HIV) at enrollment were followed for six months to elucidate risk factors for seroconversion to HIV. 95 (3.8%) seroconverted. Of men who did not engage in receptive anal intercourse within six months before baseline and in the six-month follow-up period, only 0.5% (3/646) seroconverted to HIV. By contrast, of men who engaged in receptive anal intercourse with two or more partners during each of these successive six-month intervals, 10.6% (58/548) seroconverted. No HIV seroconversions occurred in 220 homosexual men who did not practise receptive or insertive anal intercourse within twelve months before the follow-up visit. On multivariate analysis receptive anal intercourse was the only significant risk factor for seroconversion to HIV, the risk ratio increasing from 3-fold for one partner to 18-fold for five or more partners. Furthermore, data for the two successive six-month periods show that men who reduced or stopped the practice of receptive anal intercourse significantly lowered their risk of seroconversion to 3.2% and 1.8%, respectively. Receptive anal intercourse accounted for nearly all new HIV infections among the homosexual men enrolled in this study, and the hazards of this practice need to be emphasised in community educational projects.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Strongly enhanced sensitivity of a direct anti-HIV-1/-2 assay in seroconversion by incorporation of HIV p24 ag detection: a new generation vironostika HIV Uni-Form II.

The clinical sensitivity of the current anti-HIV assays is based for an important part on their reactivity with seroconversion panels. The most sensitive assay closes the seroconversion window as much as possible, thereby reducing the risk of transmitting false negative donations obtained from individuals infected recently. Because of the absence of anti-HIV antibodies during the early phase of infection, the seroconversion window can be narrowed partially by detection of HIV p24 Ag. To achieve this, the highest affinity anti-p24 binding antibodies were selected with BlAcore and applied in a direct assay format. To achieve optimal conditions for the anti-HIV part of the assay the HIV specific antigens viral HIV-1 gp160, HIV-2 gp36 and HIV-1 group O gp41 peptides were used. These antigens and antibodies were applied for microELISA coating as well as in the conjugate pearl, which is present in the well of the microELISA plate. The (analytical) anti-HIV-1/-2 and anti-HIV-1 group O sensitivity of this new assay, Vironostika HIV Uni-Form II Ag/Ab, is at least at the level of the current Vironostika HIV Uni-Form II plus O. When compared to the Vironostika HIV Uni-Form II plus O, the seroconversion window is narrowed by 1-2 weeks due to the incorporation of HIV p24 Ag detection. The level of reactivity of the anti-HIV and HIV Ag detection part can be improved by about a factor 2 by applying continuous shaking during sample incubation. Initial studies suggested that the specificity of the assay is identical to that of the Vironostika HIV Uni-Form II plus O, namely > 99.9%. Monitoring of proper execution of the assay handling steps was facilitated by implementing a purple dye in the conjugate pearl. Colourless specimen diluent changes into a green fluid upon dissolving of the conjugate pearl and turns subsequently into blue/purple upon sample addition. These visual changes can also be determined by spectrophotometric measurement at 620 nm.

Enzyme-Linked Immunosorbent Assay↗

PubMed2000

Persistence of viral replication after anti-HBe seroconversion during antiviral therapy for chronic hepatitis B.

BACKGROUND/AIMS: Hepatitis B virus genome mutants may be selected during the immune-mediated clearance of infection or during long-term nucleoside analog administration and may escape both antiviral pressures. The pattern of anti-HBe seroconversion was analyzed in patients receiving new nucleoside analogs, lamivudine or famciclovir, in comparison with patients treated with interferon alpha. METHODS: Eighteen consecutive patients who seroconverted to anti-HBe were included in the study. Serial serum samples were studied with the quantitative determination of HBV DNA by the branched DNA assay (Chiron) and by a quantitative PCR assay (Roche diagnostics), determination of pre-S1 Ag, the genetic analysis of the viral genome with the determination of pre-core promoter or pre-core region mutations with a line probe assay (Innogenetics) and, in selected samples of polymerase gene mutations. RESULTS: The quantitative PCR assay was found to be more sensitive than the bDNA assay, allowing a 25-log decrease in viral DNA levels to be demonstrated after anti-HBe seroconversion. Viral persistence after anti-HBe seroconversion induced by interferon, lamivudine or famciclovir, was often associated with circulating HBV genomes harboring mutations in the precore promoter. The clinical significance of these findings was demonstrated by the observation of reversion to HBeAg in two patients treated with interferon and one with lamivudine. CONCLUSION: Persistence of significant levels of viremia that are not detected by the branched DNA assay may be observed after anti-HBe seroconversion. A precise monitoring of viremia levels with more sensitive assays and HBV mutant strains is warranted in patients undergoing antiviral therapy.

2-Aminopurine↗