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PubMed1981

Seroconversion from hepatitis B e antigen to antibody in chronic type B hepatitis.

Twenty-five patients with chronic type B hepatitis documented by liver biopsy were followed for 1 to 6 years with serial measurements of aminotransferase levels, hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) and antibody (anti-HBe), and hepatitis B virus DNA polymerase. Initially, all were positive for HBsAg and HBeAg and had elevations in serum aminotransferases. In follow-up, only one lost HBsAg reactivity. In 13, however, elevated aminotransferase levels spontaneously fell to normal and have remained normal. These 13 also had a seroconversion from HBeAg to anti-HBe, and all became negative for serum DNA polymerase. Most had a fall in HBsAg titer. This seroconversion occurred concurrently with or several months before the fall in aminotransferase levels. In contrast, the 12 persons who remained HBeAg positive continued to have elevated aminotransferase levels. All 10 of these patients who were initially positive for DNA polymerase remained positive. These data suggest that many patients with chronic type B hepatitis eventually have a spontaneous remission in clinical and biochemical evidence of active disease, usually heralded or accompanied by the disappearance of HBeAg and DNA polymerase.

Adult↗

PubMed1987

Seroconversion rates to Jamestown Canyon virus among six populations of white-tailed deer (Odocoileus virginianus) in Indiana.

The annual seroconversion of fawns, yearlings, and adult white-tailed deer (Odocoileus virginianus) to Jamestown Canyon virus (California group) was followed at six Indiana sites from 1981 through 1984. In all, sera from 1,642 deer (515 fawns, 618 yearlings, and 509 adults) were tested for neutralizing antibody to three California serogroup viruses: Jamestown Canyon, La Crosse, and trivittatus. Virtually all deer with specific neutralizing antibody showed evidence of a prior infection with Jamestown Canyon virus; only three deer showed evidence of a prior infection with only La Crosse virus and none showed evidence of an infection with only trivittatus virus. While there were no significant differences in antibody prevalence to Jamestown Canyon virus between yearling and adult deer at any site, fawns had significantly lower antibody prevalences than either of the two older age groups. Significant differences in antibody prevalence were found between northern versus southern populations of white-tailed deer in Indiana, however, no significant differences were found among the four northern populations or between the two southern populations. The mean antibody prevalences in the two southern fawn, yearling, and adult populations were 15%, 38%, and 41% respectively, while the prevalences in the four northern fawn, yearling, and adult populations were 5%, 67%, and 67% respectively. These different prevalences (northern vs. southern) correlate with the higher Jamestown Canyon virus antibody prevalence in human residents of northern Indiana (2-15%) compared to residents of southern Indiana (less than 2%) found in other studies. The significantly lower prevalence of antibody to Jamestown Canyon virus in fawns is attributed to maternal antibody protecting them from a primary infection their first summer. Yearling deer showed high rates of seroconversion following their second summer of life. These results suggest that infection of white-tailed deer in Indiana with Jamestown Canyon virus is a common phenomenon.

Animals↗

PubMed1992

Monthly incidence of Theileria cervi and seroconversion to Babesia odocoilei in white-tailed deer (Odocoileus virginianus) in Texas.

Monthly monitoring of fawns collected from an area in Texas endemic for Theileria cervi and Babesia odocoilei showed that transmission of T. cervi occurred during July and August, a time period consistent with the occurrence of Amblyomma americanum. Seroconversion to B. odocoilei occurred during October to December and possibly continued through January and February. The time of seroconversion was more suggestive of transmission of B. odocoilei by Ixodes scapularis than by Amblyomma americanum.

Animals↗

PubMed2000

Survival after introduction of HAART in people with known duration of HIV-1 infection. The CASCADE Collaboration. Concerted Action on SeroConversion to AIDS and Death in Europe.

We compared survival from HIV-1 seroconversion before and during the periods of highly-active antiretroviral therapy (HAART). Survival expectations were substantially better for HIV-1-infected individuals in 1997-98 (HAART period) compared with those in 1986-96 (pre-HAART period). Estimated survival 10 years from seroconversion was also substantially better in the later period.

Adolescent↗

PubMedDate not supplied

Low rates of seroconversion after hepatitis B vaccination in orphanges with high prevalence of virus carriers.

A serosurvey of Hepatitis B infection markers was conducted in two orphanages that adhered to Hepatitis B vaccination policy. In spite of comparable sizes (80-90 children per facility), housing conditions and infection control practices, the level of HbsAg endemicity was different in each unit in direct relation with the mean age of the children. The prevalence of HbsAg carriers and the interval spent in collectivity strongly affect the seroconversion rate after HB vaccination. Other elements that can explain the low seroconversion rate were: the proportion on fully vaccinated children, the number of vaccine administered doses and the delayed age at which childhood immunization schedule was initiated. In order to increase the protective antibody response, booster doses were administered to a limited number of nonseroconvertors or to children with a nonprotective level of anti-HBs antibody (< 10 UI). This intervention provides evidence of prompt rising in antibody titers, comparable with titers found in children with wild infection.

Carrier State↗

PubMed1992

[3-day fever: agreement between clinical diagnosis and seroconversion of type 6 human herpesvirus (HHV-6)].

The aim of this study was to investigate the correlation between clinical diagnosis of exanthema subitum and seroconversion of herpes virus type 6 (HHV-6). 90 children with fever of unknown origin were investigated by 11 pediatricians in the Canton of Zürich, Switzerland, between October 1989 and June 1990. Antibodies against HHV-6 were determined at the first consultation and 2-3 weeks later. History and clinical findings were investigated and the clinical probability of the diagnosis exanthema subitum was estimated. 82 of the 90 children could be evaluated. 33 of them already had HHV-6 antibodies in their first blood sample although their history was negative concerning exanthema subitum. In 24 children exanthema subitum was proven by seroconversion. The clinical diagnosis was much more reliable at the second consultation compared to the first one. The clinical course of the disease was highly variable. Duration of fever differed widely and in some children the exanthema was atypical or even absent.

Antibodies, Viral↗

PubMedDate not supplied

Behaviour of several 'progression markers' during the HIV-Ab seroconversion period. Comparison with later stages.

Two acute phase reactants, four cytokines, five soluble factors and lymphocyte subpopulations have been simultaneously evaluated in 16 subjects before and closely after the HIV-Ab seroconversion time. The same variables have also been determined in 50 HIV-Ab-negative high risk subjects, in 36 CDC II-III and in 30 CDC IV patients, utilizing a mixed longitudinal epidemiological model. The results show significant variations of few parameters in the early phases (increase: sCD8, beta-2-Microglobulin, sIL-2R, sCD23, Neopterin, IFN-alpha; decrease: CD4+ lymphocytes). In the course of the disease, many others parameters progressively increase (IFN-tau, IL-4, IL-6, acid-alpha 1-glycoprotein, alpha 1-antitrypsin) or decrease (B- and T-lymphocytes). Ferritin, in particular, highly increases only in CDC IV stage. These data may be useful to monitor patients during the entire course of their disease and to suggest the time elapsed from seroconversion.

Acute-Phase Proteins↗

PubMed2004

[The HBeAg/antiHBe seroconversion as a result of lamivudine treatment in children with chronic hepatitis B unresponsive to previous interferon alpha therapy].

UNLABELLED: The aim of the study was evaluation the HBeAg/antiHBe seroconversion frequency as a result of lamivudine treatment in children who are nonresponders to previous IFN-alpha therapy. MATERIAL AND METHODS: The observation was carried out on 41 children, aged 4-17 years, with biopsy-proven chronic hepatitis B (HBeAg+) treated with lamivudine 3-4 mg/kg/d (max. 100 mg/d) for 12 months. RESULTS: After 6 months of lamivudine therapy 59.3% children normalized GPT activity and only 1 child (2.5%) lost HBeAg. At the end of 12 months of therapy 81.5% normalized GPT activity and 4 of them (10%) lost HBeAg and seroconverted to antiHBe. None of treated children lost HBsAg. The age, sex, pretreatment GPT activity and active histological disease were not predictors of lamivudine-induced HBeAg loss. There were no side effects of lamivudine therapy except one boy who had severe thrombocytopenia. CONCLUSIONS: The HBeAg/antiHBe seroconversion rate after one year trial of lamivudine in children with chronic hepatitis B unresponsive to previous IFN alpha therapy was 10%. The age, sex, pretreatment GPT activity and active histologic disease were not predictors of lamivudine-induced HBeAg loss.

Adolescent↗

PubMed2005

[HBV-specific CD8+ T cells for sustained HBeAg seroconversion after lamivudine therapy].

BACKGROUND/AIMS: Viral suppression of the hepatitis B virus (HBV) can be induced by lamivudine, but the relapse seen in many patients after cessation of lamivudine therapy is troublesome. We thought that the host immune response is important to prevent viral relapse. We compared the frequency of HBV-specific CD8+ T cells in the peripheral blood and their expansion capacity after exposure to viral antigen between the patients showing sustained HBeAg seroconversion after use of lamivudine and those patients without sustained response. METHODS: We analyzed HBV-specific CD8+ T cells that were isolated from the blood of 14 patients with HLA-A2 who showed lamivudine induced HBeAg seroconversion (HBV DNA < 0.5 pg/mL, and the cells were negative for HBeAg) at the end of lamivudine therapy. The purified T cells were directly stained ex vivo, after they had been stimulate with synthetic peptide, using the HBV core 18-27-specific HLA tetramer (Tc 18-27) and monoclonal antibody to CD8. The HBV viral load was quantified by the Amplicor HBV Monitor assay. RESULTS: In patients with a sustained HBeAg response (the sustained group) for a duration of 15.5 months of follow-up, the median number of Tc 18-27 cells out of the 5 X 10(4) CD8+ T cells was 49.5 (15-135). On the contrary, in patients who experienced relapse (the relapsed group) during a median of 7.5 months of follow-up, the median number of Tc 18-27 cells out of the 5 X 10(4) CD8+ T cells was 13.5 (0-95). Especially, among patients with a viral load of HBV DNA < 1 X 10(3) copies at the end of treatment, the median number of Tc 18-27 cells out of 5 X 10(4) CD8+ T cells was 87 (45-135) in sustained group compared to 12 (6-50) in the relapsed group. All patients in the sustained group demonstrated a vigorous expansion of the core 18-27-specific CD8+ T cells after stimulation with viral peptide, in contrast to only 3 out of 8 patients in the relapsed group. CONCLUSIONS: This study demonstrates that the frequency and functional responsiveness of the circulating HBV-specific CD8+ T cells may be important for obtaining a sustained HBeAg response to lamivudine.

Adult↗

PubMed1991

Detection of early human T-cell lymphotropic virus type I antibody patterns during seroconversion among transfusion recipients.

From a cohort of human T-cell lymphotropic virus type I (HTLV-I) exposed transfusion recipients (N = 71) enrolled in the Jamaican Transfusion Study, 11 were selected for detailed laboratory evaluation. All recipients were followed at monthly intervals for 6 months and then bimonthly up to 1 year for evidence of HTLV-I seroconversion. Without regard to results on screening assays, pretransfusion and posttransfusion samples were tested with two licensed HTLV-1 whole-virus screening enzyme immunoassays (EIAs), recombinant EIAs for antibody against tax (p40x) and p21e envelope, standard whole virus Western blot (WB), WB enhanced with recombinant p21e, and radioimmunoprecipitation assay (RIPA). In the early period posttransfusion, antibody to gag core protein was predominant with anti-p24 generally appearing before anti-p19. Recombinant anti-p21e envelope protein, in EIA and WB format, was frequently the earliest envelope reactivity detected, while anti-gp46 in WB and anti-gp61/68 in RIPA system appeared later. Anti-tax antibodies appeared later in the time course of seroconversion. The whole-virus EIAs were less sensitive than the confirmatory assays. The combination of WB and RIPA or WB enhanced with recombinant p21e appeared equally effective in confirming samples as positive by the Public Health Service two gene group confirmatory algorithm. However, specificity of this assay approach could not be addressed in this study.

Adolescent↗

PubMed1989

A simple method to detect and estimate heterogeneity: application to Huntington disease, diabetes, and HIV seroconversion.

The traditional method for calculating risk in prospective and retrospective studies is based on the assumption that the study population is homogeneous. Risk is therefore estimated as an overall average for the entire population, when in fact some individuals may be at high risk and others at little or no risk. This paper introduces an alternate approach to risk estimation. The calculations are equally simple and utilize the same data. Yet, the new approach allows for heterogeneity and can detect it when it exists. The new method was applied to HIV seroconversion data from a follow-up study, age-at-onset distribution for Huntington disease, and age-specific prevalence of insulin-treated diabetes. These analyses were intended to demonstrate both applicability of the method to different types of data and the accuracy of the estimates when compared with the known parameters. The HIV analysis predicted a high-risk subgroup constituting about 17% of the cohort. This estimate closely approximates the actual 16% who reportedly engaged in high-risk activities and had a 15-fold higher seroconversion rate than the rest of the cohort. There is no evidence from genetic linkage studies for heterogeneity in Huntington disease. The present results, however, suggested that 14%-18% of individuals who are susceptible to the disease have a much lower risk than others. Diabetes data was chosen because the model is clearly too simplistic for this disease, and the analysis did reveal lack of fit of the model.

Adult↗

PubMed1989

Blood donation and HIV infection: impact of seroconversion delay on the sensitivity of the testing procedure.

This study estimates the impact of the delay of seroconversion on the global sensitivity of the testing procedure among regular blood donors who give 80% of blood donations in France and in the USA. When applied to the 1987 French data, an estimate of 77 to 161 false negative donations, depending on the assumption concerning the mean seroconversion delay, was obtained, as compared to the 388 positive donations detected. The global sensitivity of the testing procedure ranged from 70 to 83%. When applied to the 1986-87 American data, an estimate of 192 to 432 false negative donations was obtained, as compared to the 1728 positive donations detected. The global sensitivity of the testing procedure ranged from 80 to 90%. These results emphasize the need to recruit blood donors in low risk subgroup populations and to develop more sensitive biological tests.

Blood↗

PubMed1986

AIDS retrovirus antibodies in hemophiliacs treated with factor VIII or factor IX concentrates, cryoprecipitate, or fresh frozen plasma: prevalence, seroconversion rate, and clinical correlations.

Antibodies to the AIDS retrovirus, specifically to human T cell lymphotropic virus, type III, and AIDS-associated retrovirus, were detected with increasing prevalence in a population of 190 hemophiliacs from western Pennsylvania between 1981 and 1984: 7.7% in 1981, 20.0% in 1982, 45.5% in 1983, and 62.5% in 1984. The seropositive included approximately three fourths of those receiving factor VIII concentrate, nearly one third of those receiving factor IX concentrate, nearly one fifth of those receiving cryoprecipitate, and none of those receiving fresh frozen plasma. The seroconversion rate, determined on 43 seropositive hemophiliacs from this group who were serially sampled, was 0% in 1977, 4.7% in 1978, 4.9% in 1979, 2.6% in 1980, 10.5% in 1981, 52.9% in 1982, 87.5% in 1983, and 100% in 1984. Of 27 seropositive for three or more years (since 1982 or before), four (15%) have developed AIDS and seven (26%), diffuse lymphadenopathy (ARC); of 16 seropositive for less than three years, none has developed AIDS and three (19%) have developed ARC. The mean time from seroconversion to onset of ARC, 0.8 +/- 0.2 years (SEM), was shorter (P less than .001) than the time to onset of AIDS, 4.1 +/- 0.6 years. These findings confirm the widespread presence of AIDS retrovirus and support the association of these retroviruses with the acquired immunodeficiency syndrome and related conditions.

Acquired Immunodeficiency Syndrome↗

PubMed1973

Poliomyelitis vaccination of infants: preimmunization status and seroconversion.

A study was carried out in Delhi on the preimmunization status of infants aged 2-6 months with regard to poliomyelitis and on seroconversion after the administration of oral poliomyelitis vaccine. It was found that 30.3% of the 204 infants included in the study excreted enteroviruses, 58% of which were found to be polioviruses. Of 197 sera examined for neutralizing antibodies against different types of poliovirus, 73% were found to be triple negative and only 4.0% triple positive. Three doses of oral poliomyelitis vaccine were administered at intervals of 1 month. It was found that 71.8% of the vaccinated infants excreted cytopathogenic agents in the 7 days following the first dose; 80.4% of these agents were found to be polioviruses. Seroconversion was studied in 71 infants, and good antibody responses to all three types of poliovirus were observed.

Antibodies, Viral↗

PubMed1979

Rubella seroconversion following immunization in a rural practice.

One hundred two consecutive patients with verifiable immunization to rubella were studied in a rural West Virginia county. Hemagglutination Inhibiting (HI) antibody titres, age at immunization, and elapsed time since immunization were recorded. Twenty-three (22.5 percent) had HI titres less than 1:8. There was no statistically significant difference in whether immunization at less than 15 months or more than 15 months of age resulted in a titre of greater than or equal to 1:8. There was no evident change in group proportion of seroconversion with time; either the child initially had a seroconversion with immunization, or he/she did not. A relatively large number of children with verified immunization to rubella do not have a titre currently considered protective to rubella. This does not seem to vary with time since immunization or age at immunization.

Adolescent↗

PubMed1976

Associated seroconversions to respiratory viruses in volunteers with experimental influenza infection.

Serological examinations of 573 volunteers with mild experimental influenza infection and 86 volunteers of a control group hospitalized in a special clinic revealed a significant rise in the titre of antibodies (seroconversion) not only to influenza A or B viruses used for the experimental infection but in 23.3 to 29.8% of cases also to other respiratory viruses. Based on a number of arguments, associated seroconversions are interpreted as due to mixed or sequential infections of different aetiology.

Adenoviridae↗

PubMedDate not supplied

Seroconversion rates and measles antibody titers induced by measles vaccination in Latin American children six to 12 months of age.

A collaborative study was conducted to determine how 2,042 infants responded serologically to measles vaccination in six study areas and to help define the optimal age for measles vaccination in children of Latin America. The results suggest that local factors affect the seroconversion rate and that a success rate of 90% can be attained if initial vaccination is given at nine to 11 months of age, depending on the area. Post-vaccination titers also varied, and higher titers were generally observed in groups with higher seroconversion rates.

Age Factors↗

PubMedDate not supplied

Investigations on HBe antigen. Note II. Dynamics of HBsAg in acute viral hepatitis, according to HBeAg persistence or seroconversion.

Serum samples collected at 10-day intervals from 146 patients with acute viral hepatitis were tested for the presence of HBsAg, HBeAg and anti-HBe. During an observation period of 4 months HBe system seroconversion occurred in 70.5% of the the patients; a persistence of HBeAG was recorded in the remaining cases. Lower values of HBsAg prevalence and a shorter persistence of this antigen were recorded in the patients with HBe system seroconversion as compared with those showing HBeAg persistence, and in female as against male patients.

Acute Disease↗