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Results for “seroconversion”

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PubMed2001

Increase in the share of steady partners as a source of HIV infection: a 17-year study of seroconversion among gay men.

OBJECTIVES: To examine the share of steady versus casual partners as the source of HIV infection in gay male seroconversions between 1984 and 2000 and the effect of age at seroconversion on the source of HIV transmission. METHODS: The sample consisted of 144 seroconverstors from the Amsterdam Cohort Study among Homosexual Men. Questionnaires and post-seroconversion interviews were used to determine the source of HIV transmission. RESULTS: Analysis revealed an interaction effect between calendar year and age at seroconversion (P < 0.05). Younger seroconverters had higher odds ratios [odds ratio, 11.33; 95% confidence interval, 1.77--72.13] to be infected by their steady partner late in the AIDS epidemic: 15% (three of 20) between 1984 and 1987 versus 67% (six of nine) between 1994 and 2000. No such time effect was present for older seroconverters who were consistently more likely to be infected by a casual partner: 79% (37 of 47) between 1984 and 1987, and 83% (15 of 18) between 1994 and 2000. CONCLUSIONS: Young gay seroconverters today are more likely to have contracted HIV from a steady partner than from a casual partner, compared with early in the AIDS epidemic and compared also with older gay seroconverters. There is a pressing need for preventive measures addressing sexual risk behaviour within steady relationships among younger gay men.

Adult↗

PubMed2001

HIV-1 seroconversion in United States Army active duty personnel, 1985-1999.

OBJECTIVE: To monitor HIV-1 infection trends among United States Army personnel, a predominantly young population group, tested between 1985 and 1999 for HIV-1 infection. DESIGN: Demographic correlates of HIV-1 infection were assessed in the cohort via epidemiologic analysis. METHODS: Annual seroconversion incidence rates were calculated per 1000 person-years (PY) of follow-up. Poisson regression was used to assess demographic correlates of HIV-1 seroconversion risk. RESULTS: There were 1275 seroconverters among 2 004 903 active duty Army personnel accounting for 7 700 231 PY of follow-up. The HIV-1 incidence rate (IR) was 0.17/1000 PY [95% confidence interval (CI), 0.16-0.17]. The highest IR was observed in the first year of testing (IR, 0.43/1000 PY; 95% CI, 0.33-0.52). The IR for male and female soldiers was 0.18/1000 PY and 0.08/1000 PY, respectively. HIV-1 incidence declined with age. Significant risk of HIV-1 seroconversion was associated with age [> 30 years old relative risk (RR), 1.51], race (Black RR, 4.61; Hispanic RR, 2.76), gender (male RR, 3.12), marital status (unmarried RR, 2.01) and rank (enlisted RR, 2.50). CONCLUSIONS: HIV-1 seroconversions in the US Army have been low and stable since the early 1990s. Continued HIV-1 incidence surveillance in the US Army provides information on the status of the epidemic in the Army, as well as important corroborative data on HIV-1 infections throughout the US.

Adult↗

PubMed1996

Long-term persistence of hepatitis B virus DNA in the serum of children with chronic hepatitis B after hepatitis B e antigen to antibody seroconversion.

To evaluate the prevalence and duration of viremia in relation to the features of liver disease, we investigated hepatitis B virus (HBV) DNA by the polymerase chain reaction in the serum of 39 children with chronic hepatitis B, after hepatitis B e antigen to antibody seroconversion. During a mean observation period of 8.2 +/- 3.8 years after seroconversion, all patients were asymptomatic; 36 had persistently normal alanine aminotransferase levels, and three had occasional mild alterations. Liver histology, checked in 21 patients, showed persistent hepatitis in nine, fibrosis in 10, and cirrhosis in two cases. HBV DNA was always undetectable by dot blot hybridization. Five children eventually cleared hepatitis B surface antigen, including one with cirrhosis who developed liver cancer at 19 years. HBV DNA was detected by polymerase chain reaction in 87% of children within 5 years of follow-up, in 58% of cases 6-10 years after seroconversion (p < 0.001), and in 50% of patients investigated later. Long-term viremia was found in two patients (40%) who cleared HBsAg, including the one who developed liver cancer. The chances of clearing viremia during follow-up were higher in children with acute hepatitis at the onset of illness (86%) than in those with asymptomatic onset (37%; p < 0.05). Our results show that low levels of HBV viremia, probably reflecting low levels of virus replication, persist for several years in children with chronic hepatitis B after hepatitis B e antigen to antibody seroconversion and remission of liver disease, even after the clearance of hepatitis B surface antigen. Persistent replication could support mild biochemical alterations and inflammatory liver lesions. It could allow late reactivation of liver disease and may play a role in the development of carcinoma.

Alanine Transaminase↗

PubMed2001

Clinical relevance of precore and basal core promoter variants of hepatitis B virus during natural hepatitis B e antigen seroconversion may be overstated.

BACKGROUND: Clinical relevance of nucleotide changes in precore and basal core promoters in the hepatitis B virus genome during hepatitis B e antigen seroconversion may be overstated. The authors investigated the existence and changes in the relative proportion of variants to wild virus that occur with seroconversion. METHODS: Sera from 30 school-aged long-term hepatitis B virus carriers, including 11 tested before and after seroconversion during 1 to 8 years of follow-up, were evaluated for variations in nucleotide sequences of the basal core promoter (T1762 and A1764), precore region (A1869), and carboxyl-terminus of the X region of the hepatitis B virus genome using an amplification refractory mutation detection system with mutant-specific primers. RESULTS: All variants were found to already exist before seroconversion at various wild-type/mutant ratios. The positive rates of these variants were not changed with loss of hepatitis B e antigen. Although there was a relative increase in the concentration of these mutants in wild-type/mutant mixed populations, most patients with only a wild-type population maintained the same pattern after loss of hepatitis B e antigen. CONCLUSIONS: Our results indicate that hepatitis B virus exists as a quasi species, and correlations of nucleotide sequences with clinical and serologic findings must be done with caution.

Adolescent↗

PubMed2001

Human herpesvirus-8 seroconversions after renal transplantation.

BACKGROUND: Human herpesvirus-8 (HHV-8) is a new human herpesvirus that is clearly associated with Kaposi's sarcoma (KS). A previous study has reported that the prevalence of KS in a cohort of renal transplant recipients with previous HHV-8 infection was 28% and two other studies have shown that KS can be linked to HHV-8 seroconversion after graft. The aim of this study was to evaluate the HHV-8 seroconversion rate in a cohort of renal allograft recipients in Paris. METHODS: Two hundred eighty-seven patients who were HHV-8 seronegative before renal transplantation were tested for HHV-8 antibodies by an immunofluorescence assay 12 months after transplantation. RESULTS: Of the 287 patients, 6 (2.09%) seroconverted after renal transplantation. None of these 6 patients developed KS within 3 years of the first HHV-8 positive serum. None of the clinical manifestations that could be associated with HHV-8 primary infection were observed during the seroconversion. CONCLUSIONS: Our results demonstrated that HHV-8 seroconversion can be observed even in a low HHV-8 prevalence area and confirmed the need to perform systematic screening for HHV-8 antibodies in renal graft donors and recipients.

Adult↗

PubMed1996

Weight loss associated with HIV seroconversion among injection-drug users.

To describe symptoms associated with human immunodeficiency virus (HIV) seroconversion, we studied a cohort of 366 injection-drug users (IDUs) with a study design that included recall every 3 months to collect symptom histories using a structured questionnaire. Eleven HIV seroconversions were observed in 621.5 person years at risk (PYAR), equivalent to 1.8 seroconversions/100 PYAR. Cox regression analysis showed age < or = 35 years to be a significant risk factor for HIV seroconversion after controlling for gender, race, and the frequency of drug injection. An embedded case-control analysis then compared symptom histories of HIV seroconverters with those of age-(+/- 5 years) and visit number-matched controls who remained HIV seronegative for > or = 3 months longer than the HIV-seroconverters. Multivariate case-control analysis adjusted for injection frequency yielded significant associations of HIV seroconversion with histories of weight loss > or = 4.5 kg (seven of 11 cases; odds ratio [OR] = 11.6, 95% confidence interval [CI] 3.1, 43.1) and oral ulcers (three of 11 cases; OR = 7.6, 95% CI = 1.2, 48.2) in the 3 months before the subjects' first HIV-seropositive study visit. We conclude that histories of recent symptoms reported by HIV-seroconverting IDUs differ from those reported by non-HIV-seroconverting IDUs, and weight loss may be particularly common among IDUs experiencing primary HIV infection.

Adult↗

PubMed1996

Virologic and serologic markers of rapid progression to AIDS after HIV-1 seroconversion.

The association between early virologic and immunologic events after human immunodeficiency virus type 1 (HIV-1) infection and progression of HIV-1 infection to acquired immunodeficiency syndrome (AIDS) was studied among 59 homosexual men with documented time of seroconversion. Epidemiologic factors, such as number of lifetime sexual partners, history of sexually transmitted diseases, and other factors, also were studied. All 17 seroconverters in the cohort who developed AIDS within 3 years (rapid progressors = RPs) were compared with 42 men without AIDS for at least 6 years seroconversion (nonrapid progressors = non-RPs). Plasma levels of HIV-1 RNA, p24 antigen, antibodies to HIV-1 structural genes, beta-2 microglobulin, neopterin, and interferon-alpha were measured at four time points: (a) the last seronegative visit, (b) the first seropositive visit, (c) the visit closest to AIDS (or the corresponding visit for the non-RPs) and (d) 6 years after seroconversion (for non-RPs). Up to seroconversion, the RPs had a significantly higher number of lifetime sexual partners than non-RPs (503 versus 171, respectively). At the first seropositive visit, RPs had significantly higher concentrations of plasma HIV-1 RNA (p < 0.01) and prevalence of p24 antigenemia (p < 0.001) and significantly lower levels of antibodies to the HIV-1 gag proteins p17 and p24 (p < 0.01-0.001) compared with non-RPs. These differences increased during follow-up visits. Antibodies to p66 and gp120 were significantly different only at the visit closet to AIDS (p < 0.001), as were beta-2 microglobulin and interferon alpha. These findings suggest that early virologic-immunologic events after HIV-1 infection may determine the rate of progression to AIDS. Anti-gag immune response may prevent rapid progression of HIV-1 disease and should be considered for future vaccine studies.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Prognostic value of serum HIV-RNA levels at virologic steady state after seroconversion: relation to CD4 cell count and clinical course of primary infection.

The objectives of this study were to evaluate the prognostic value of a single serum HIV-RNA measurement 6-24 months after HIV seroconversion, and to investigate whether any differences in outcome related to the clinical course of primary infection could be explained by presumed steady-state HIV-RNA levels at 6-24 months after seroconversion. Disease progression was analyzed by life tables and Cox proportional hazard models. A total of 93 HIV seroconverters followed for a median of 76 months (range, 19-143 months) were included in the study. The main outcome measures were development of AIDS stratified by age, the year of seroconversion, serum HIV-RNA levels, CD4 cell counts, and duration of primary illness. The proportion of patients who developed AIDS was 36% (95% confidence interval, 22%-50%) at 8 years and 50% (26%-75%) at 10 years. In the unadjusted analyses, clinical progression was significantly associated with serum HIV-RNA levels, CD4 cell counts, and duration of primary illness. The adjusted analyses indicated that HIV-RNA was the strongest predictor. Patients with long-lasting symptoms associated with primary infection had significantly higher serum HIV-RNA levels than those with less severe presentations (median counts, 11,660 vs. 2880 copies/ml, p = 0.001). It is concluded that the serum HIV-RNA level in early HIV infection is a strong independent predictor of clinical progression. Patients with long-lasting primary illnesses reach a higher viral load in steady state after seroconversion, which is probably the main reason for the poorer prognosis observed in this group of patients.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Direct comparison of time to AIDS and infectious disease death between HIV seroconverter injection drug users in Italy and the United States: results from the ALIVE and ISS studies. AIDS Link to Intravenous Experiences. Italian Seroconversion Study.

OBJECTIVE: To compare the rate of HIV disease progression in a sample of polydrug injectors (AIDS Link to Intravenous Experiences [ALIVE] study) with that in a sample of predominantly opiate injectors (Italian Seroconversion Study [ISS]). DESIGN: Prospective cohort studies of HIV-positive individuals whose date of seroconversion (SC) is known with a good degree of precision. The ALIVE study involves a community-based cohort of injection drug users (IDU) in the United States and the ISS reports on a clinic-based cohort of seroconverters in Italy with different exposure modalities to HIV. METHODS: Data from the two cohorts were combined. The date of SC was estimated as the midpoint in time between the last negative and the first positive HIV test. Time-to-event (i.e., AIDS or death from an infectious disease) statistical methods were used. Relative hazards (RH) of progression to event were adjusted by age at SC, gender, and year of SC. RESULTS: Of the 1003 IDUs (251 from ALIVE and 752 from ISS), 226 progressed to AIDS, and 146 died after AIDS or from an infectious disease; of these, 10 were without an AIDS diagnosis. The two groups of IDUs differed in terms of age at SC (median, 35 years for ALIVE and 25 years for ISS), proportion of women (24% versus 31%), race (7.6% versus 100% white), and year of seroconversion (i.e., ISS participants seroconverted, on average, earlier than ALIVE participants). Although the univariate analysis suggested possible differences for progression to AIDS, or to death from infectious disease between cohorts, multivariate analyses that adjusted for age showed no significant differences by cohort, gender, race, or time of seroconversion. The median time to AIDS for 25-year-old persons was 12.3 years for ALIVE and 11.8 years for ISS; for 35-year-old persons, it was 8.5 and 8.2 years, respectively. These estimates were similar to those for non-IDUs observed in the ISS and to those from large cohort of homosexual men. CONCLUSION: Our results confirm the importance of accounting for age when considering the incubation period for HIV infection. Despite differences in drug use characteristics, the similar median times to AIDS, for each age, between the two cohorts of IDUs and between the IDUs and the non-IDUs suggest a negligible effect of injection drug use on HIV progression.

Acquired Immunodeficiency Syndrome↗

PubMed2004

HIV seroconversion among the homeless and marginally housed in San Francisco: a ten-year study.

HIV seroprevalence was previously found to be 9-11% among the urban homeless in San Francisco, with most infections among injection drug users, men who have sex with men, and those who exchange sex for money or drugs. In this study, HIV incidence and risk factors for seroconversion were estimated among persons who repeatedly participated in cross-sectional serosurveys over a period of 10 years. There were 6 seroconversions among 799 HIV-negative persons, for an incidence rate of 0.30% per person-year (95% CI: 0.12-0.61% per person-year). The seroconversion rate among men who had had recent sex with men was 1.22% per person-year (95% CI: 0.29-3.18) and was 0.52% per person-year (95% CI: 0.19-1.13% per person-year) among those who ever injected drugs. The seroconversion rate among those who were aged <30 years at baseline was 1.67% per person-year (95% CI: 0.40-4.36% per person-year), which was significantly higher than for those age > or =30 years. Policy implications are that HIV resources aimed at the more stable, older homeless population should probably focus on treatment, while prevention efforts, conversely, should probably be targeted to younger homeless persons.

AIDS Serodiagnosis↗

PubMed2006

The impact of sex partners' HIV status on HIV seroconversion in a prospective cohort of injection drug users.

OBJECTIVE AND DESIGN: The identification of individuals at highest risk of HIV infection is critical for targeting prevention strategies. We evaluated the HIV status of the sex partners of injection drug users (IDUs) and rates of subsequent HIV seroconversion among a prospective cohort study of IDUs. METHODS: We performed an analysis of the time to HIV infection among baseline HIV-negative IDUs enrolled in the Vancouver Injection Drug Users Study. IDUs were stratified based on whether or not they reported having an HIV-positive sex partner. Kaplan-Meier methods were used to estimate cumulative HIV incidence rates, and Cox regression was used to determine adjusted relative hazards (RHs) for HIV seroconversion. RESULTS: Of 1013 initially HIV-negative IDUs, 4.8% had an HIV-positive partner at baseline. After 18 months, the cumulative HIV incidence rate was significantly elevated among those who reported having an HIV-positive sex partner (23.4% vs. 8.1%; log-rank P < 0.001). In a Cox regression model adjusting for all variables that were associated with the time to HIV infection in univariate analyses, including drug use characteristics, having an HIV-positive sex partner (RH = 2.42 [95% confidence interval: 1.30 to 4.60]; P = 0.005) remained independently associated with time to HIV seroconversion. CONCLUSIONS: Having an HIV-positive sex partner was strongly and independently associated with seroconversion after adjustment for risk factors related to drug use. Our findings may aid public health workers in their efforts to identify IDUs who should be targeted with education and prevention efforts and indicate the need for ongoing development of prevention interventions for IDU sex partners who are HIV discordant.

AIDS Serodiagnosis↗

PubMed2006

Incidence and risk factors for hepatitis C seroconversion in injecting drug users in Australia.

AIMS: To determine the incidence of hepatitis C virus (HCV) infection and identify risk factors for seroconversion. DESIGN: Prospective cohort study. Participants were recruited through direct approaches, street-based outreach, methadone and sexual health clinics and needle and syringe programmes. SETTING: Urban, regional and rural settings in New South Wales, Australia. PARTICIPANTS: Injecting drug users (IDUs) (n = 584) were screened and tested for exposure to HCV. Between 1999 and 2002 antibody HCV negative IDUs (n = 368) were enrolled and followed-up every 3-6 months until seroconversion or study completion. MEASUREMENTS: Interviewer-administered baseline and follow-up questionnaires consisted of 131 items and included demographics, drug use and risk behaviour. Approximately 10 cc of whole blood was drawn at each visit. Specimens were stored at -70C and serology performed using one or two third-generation enzyme-linked immunosorbent assays and polymerase chain reaction testing. FINDINGS: Sixty-eight seroconversions were observed and incidence was 30.8 per 100 person-years, with incidence in IDUs injecting < 1 year, 133 per 100 person-years. Independent predictors of seroconversion were female gender, duration of injecting, injecting cocaine, shared use of filters and recruitment strategy. CONCLUSIONS: Women, new initiates and IDUs recruited via outreach appear to be at increased risk of infection. Results confirm the significance of cocaine injection as a risk factor and provide the first evidence outside North America of the link between shared use of drug preparation equipment and incident HCV infection. Prevention efforts should attempt to raise awareness of the risks associated with drug sharing and, in particular, the role of potentially contaminated syringes in HCV infection.

Adolescent↗

PubMed1991

Sequential serological studies of homosexual men with and without HIV infection. Epstein-Barr virus activation preceding and following HIV seroconversion.

Viral cofactors may be important in the pathogenesis of HIV infection and the development of AIDS, but their role is still imperfectly understood. Sequential serological studies were performed in a cohort of 100 homosexual men and 70 matched healthy controls over a mean period of 4 years. Of the patients, 18 were found to be HIV+ on admission to the study and 15 seroconverted to HIV+ during the follow up (seroconversion group). Serum antibodies of both IgG and IgA isotypes against Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were determined. IgG antibodies indicate past infection, while a marked increase in IgG titre or a positive IgA titre were taken to indicate active infection or reactivated latent infection. EBV and CMV infections were about two to four times more prevalent in the homosexual men both HIV- and HIV+, compared with controls. Active infections were increased in the homosexual men and particularly in the HIV+ patients. The seroconversion group revealed activation of both EBV and CMV following HIV infection. When the antibody profile of seroconverting patients at the time preceding seroconversion was compared with a matched group of 39 homosexual men who remained HIV-, no change was found in CMV antibodies, but four out of 15 (26.6%) of the patients had high titres of anti-EBV IgA preceding seroconversion, as compared with only one out of 39 (2.6%) of HIV- homosexual men (P less than 0.05). This suggests a role for EBV reactivation in the pathogenesis of HIV infection in some patients.

Antibodies, Viral↗

PubMed2004

Is it possible to diagnose acute hepatitis C virus (HCV) infection by a rising anti-HCV titre rather than by seroconversion?

The diagnosis of acute hepatitis C virus (HCV) infection relies on documented positive-seroconversion of HCV antibody (anti-HCV). Because of the detection of seroconversion at an earlier stage by second or third generation anti-HCV enzyme immunoassays (EIA), the diagnosis of acute hepatitis C (AHC) may be underestimated. The aim of this study was to evaluate whether rising anti-HCV titre could be used to diagnose AHC or not. Eighteen patients with a clinical diagnosis of acute hepatitis C were enrolled, including eight cases with documented seroconversion to anti-HCV and 10 cases with clinically suspected acute hepatitis C. Four chronic hepatitis C patients with acute exacerbation were selected as a control group. Serial sera were assayed with a third generation anti-HCV (AxSYM, version 3.0; Abbott, Chicago, IL, USA) and recombinant immunoblot assays (RIBA; Chiron HCV 3.0 Strip; Immunoblot, Emeryville, CA, USA) and the titre of anti-HCV expressed as signal/cutoff (S/CO) ratio and the RIBA patterns were correlated. Seven of eight documented AHC (one lacking the initial serum) and five of 10 clinically suspected AHC showed a rising pattern of S/CO values. The initial S/CO values on the first visit were less than 40 in 14 of 18 cases. The RIBA pattern shifted from negative/indeterminate to positive in five of seven documented AHC and 4 of 10 clinically suspected AHC cases. Fifteen of 18 cases had seroconversions of at least one antibody, whilst 85.7% showed a rising S/CO ratio. On the contrary, the S/CO ratio and RIBA pattern remained unaltered in chronic hepatitis C with acute exacerbation. The rise in S/CO was usually accompanied with an increase in the number of RIBA reactive bands and their intensity in acute hepatitis C patients. The rise in S/CO ratios using a third generation anti-HCV assay and the RIBA pattern might be used as a supplemental diagnostic criterion for acute HCV infection.

Acute Disease↗

PubMedDate not supplied

Risks of seroconversion of hepatitis B, hepatitis C and human immunodeficiency viruses in children with multitransfused thalassaemia major.

OBJECTIVES: To estimate the risks of seroconversion of hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency viruses (HIV) in children with multitransfused thalassaemia at a thalassaemic clinic in Kuala Lumpur, Malaysia. METHODS: Seventy-two children (39 males, median age 11.3 years, 2.5th-97.5th centile: 1.4-19.2 years) with thalassaemia major were studied. The risks of seroconversion of HBV, HCV and HIV were estimated by comparing the seroprevalences of hepatitis B surface antigen (HBsAg), anti-HCV and anti-HIV between a defined starting point and an end point. The end point was the point when latest serological results were available while the starting point was when regular transfusion was commenced, or approximately 5 years before the end point when the duration of transfusion was longer. RESULTS: The median duration of the study was 49 months (range 8-69 months, total 2953 patient-months). There were 2605 transfusion episodes and 4154 units of blood transfused (0.88 transfusion episode/patient per month, 1.41 units of blood transfused/patient per month). There were three new seroconversions for anti-HCV but none for HBsAg and anti-HIV. The risk of seroconversion for HCV was one in 1384 units of blood transfused (95% CI: 4000-472). The seroprevalence rates at the starting and end points were: HBsAg (1%, 1%), anti-HCV (10%, 13%) and anti-HIV (0%, 0%), respectively. CONCLUSIONS: The estimated risk of acquiring HCV infection in children receiving multiple blood transfusions in this study is surprisingly higher than the generally accepted estimated risk. Other routes of transmission may be important. A prospective, multicentre study to estimate such risks more precisely is needed.

Adolescent↗

PubMed2002

Core promoter mutations 3 years after anti-hepatitis B e seroconversion in patients with chronic hepatitis B or hepatitis B and C infection and cancer remission.

OBJECTIVES: In this study, we aimed to evaluate the persistence of hepatitis B virus (HBV) DNA and the role of HBV core promoter and precore region mutations in 28 young cancer survivor patients with HBV or HBV and hepatitis C virus (HCV) infections, and persistently normal ALT levels, after spontaneous or interferon (IFN)-induced anti-hepatitis B e (HBe) seroconversion. METHODS: Sera from 15 patients with HBV and 13 with dual HBV-HCV infection were analyzed for the presence of HBV-DNA and HCV-RNA by polymerase chain reaction 3 yr after anti-HBe seroconversion. A total of 21 patients had seroconverted spontaneously and seven did so after IFN treatment. The core promoter and the precore regions were amplified sequenced directly. RESULTS: Among patients with HBV infection, HBV-DNA was detected in five of nine (55%) with spontaneous anti-HBe and in all six treated patients (p = 0.092). In the coinfected patients, four had cleared both HBV-DNA and HCV-RNA, five were HBV-DNA negative/HCV-RNA positive and four had the reverse viral pattern. Among the 15 patients with persistence of HBV-DNA, a 7-base pair nucleotide deletion in the core promoter (1757-1763) was present in seven of 10 patients with spontaneous and in one of five patients with IFN-induced seroconversion (p = 0.033). The G1896A precore stop codon mutation was never observed. HBV-DNA levels were significantly lower in patients with the core promoter deletion (p = 0.011). The 7-base pair deletion generated a truncated X protein at amino-acid position 132. CONCLUSIONS: A core promoter deletion after anti-HBe seroconversion was associated with low HBV-DNA levels, probably because of downregulation of pregenomic RNA production and truncation of the X protein. HBV-DNA persistence was a frequent event, even in the absence of active liver disease.

Adolescent↗

PubMed1996

Effect of management and inherent factors on birth seropositivity and seroconversion to Babesia bovis in calves in Costa Rica.

The relationship between calf characteristics, farm management, seropositivity, and age at seroconversion to Babesia bovis was assessed. A total of 3624 samples obtained from 494 animals on 11 farms was analyzed by an indirect ELISA assay, and individual results classified as positive or negative. The animals were sampled from birth to weaning, beginning in April 1990 and ending in April 1992. We found 59.1% (n = 467) of seropositive neonatal calves (mean age 4.4 days). Using a logistic binomial regression model as the analytical method for predicting the likelihood of calf seropositivity, we found that the following factors were related to seroconversion at birth: time to colostrum consumption, place of birth, calving history, parity (number of lactations), and ecological life zone. To analyze the effect of management factors on time to seroconversion, we used the Proportional Hazards method. In this model the pattern of seroconversion was different for the type of production system. Calves from dual-purpose farms seroconverted earlier than calves from cow-calf farms.

Aging↗

PubMed2001

HIV seroconversion interval and demographic characteristics: no evidence of selection bias.

OBJECTIVES: To determine if the interval between the last negative and the first positive HIV test is associated with demographic characteristics of HIV seroconverters. METHODS: A prospective cohort of patients with HIV seroconversion enrolled in the Lyons HIV hospital database was analysed. Comparisons of demographic characteristics were performed after stratification on the duration of the interval between the last HIV negative screening test and the first HIV positive screening test, which ranged from 1 day to 24 months. Linear regression methods were used to identify the covariates associated with a negative HIV antibody test followed by a positive test. RESULTS: Age (p = 0.54), sex (p = 0.78), heterosexual route of infection (p = 0.78), other route (p = 0.40) compared with homosexual route, and estimated year of HIV infection (p value ranged from 0.84 to 0.95) were not associated with a shorter seroconversion interval after multivariate analyses. The presence of an acute HIV illness was the only predictor of a short seroconversion interval (p = 0.006) with a reduction of 84 days of the interval when it was reported. CONCLUSIONS: No selection bias for demographic characteristics of HIV seroconverters seems associated with the length of the seroconversion interval, at least for intervals < or = 24 months.

Adult↗