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PubMed1987

Safety of an intravenous immunoglobulin preparation: lack of seroconversion for human immunodeficiency virus antibodies.

A retrospective analysis of 18 patients who had received a human intravenous immunoglobulin (IGIV) preparation was undertaken to ascertain the safety of this preparation with respect to transmission of human immunodeficiency virus (HIV), the virus that causes the acquired immune deficiency syndrome (AIDS). Patients were followed up by means of periodic enzyme-linked immunosorbent assay (ELISA) for the presence of circulating antibodies against HIV; a negative ELISA was evidence that HIV had not been transmitted to the recipients of IGIV. Results in 16 patients were negative, and two patients were determined to have had false-positive ELISAs because the Western blot test was negative for seroconversion. It is thus concluded that the IGIV product tested has little or no potential for transmitting HIV.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The association of enhancing antibodies with seroconversion in humans receiving a dengue-2 live-virus vaccine.

A group of human subjects, some with yellow fever (YF) antibodies, volunteered for testing of a live-attenuated dengue-2 (DEN-2) vaccine. Serum samples taken before DEN-2 vaccination were tested for their ability to enhance infection of human monocytes by DEN-2 virus. A significantly greater proportion of enhancing antibodies (Eab) were found in YF-immune (YFI) individuals (50%) as compared to those with no evidence of flavivirus infection (9.5%). Geometric mean titers of neutralizing and hemagglutination inhibiting antibodies to DEN-2 virus in YFI subjects with Eab were fourfold to seven-fold higher than in the YFI subjects without Eab in prevaccine sera and 10- to 35-fold higher than in non-immune volunteers. Additionally, levels of Eab in prevaccine sera were directly related to antibody titers found in postvaccine sera. The presence of Eab in the serum of a human subject before DEN-2 vaccination was a good predictor of the immune response after vaccination, and may in part be responsible for the higher seroconversion rate in YF immunes (90%) as compared to nonimmunes (61%) receiving this vaccine. This is the first human study to demonstrate that circulating Eab in non-DEN-immune persons is associated with an augmented immune response to DEN virus infection. This finding supports the hypothesis that cross-reactive antibodies against one flavivirus enhance an infection with another closely related flavivirus.

Adjuvants, Immunologic↗
PubMed1981

Optimal age for vaccinating Nigerian children against measles. II. Seroconversion to measles vaccine in different age groups.

Ninety-eight children between five and nine months were given measles vaccine. Bloodsamples were taken before and again six to eight weeks after immunization and tested for haemagglutination inhibition antibodies to measles virus. It was found that the sero-conversion rate was significantly lower (p less than 0.05) in infants under seven months than over this age. The results suggest that although some immunized at six months of age show seroconversion, the proportion is too small to justify extensive immunization at this age. It is proposed that children in Lagos should be immunized from the age of eight to nine months.

Age Factors↗
PubMed1994

A region of the third variable loop of HIV-1 gp120 is recognized by HLA-B7-restricted CTLs from two acute seroconversion patients.

HIV-1 envelope-specific CTL clones were isolated from the peripheral blood of two patients from within weeks of seroconversion. These clones were CD8+ and restricted by the HLA-B7 molecule. The minimum epitope recognized by the clones was determined to be the 30-amino acid (aa) sequence RPNNNTRKSI within the third variable (V3) loop of the envelope glycoprotein gp120. The aa sequence of this epitope is consistent with the motif found in naturally processed peptides eluted from HLA-B7 molecules. This region of the V3 loop is reasonably well conserved among clade B and some nonclade B isolates of HIV-1, especially at the anchor residues that determine binding to the HLA-B7 molecule. Using peptides based upon virus sequences present within each patient, we determined that autologous viruses were recognized by the clones, and we detected no escape variants from the initial clonal response during the acute phase of infection. Interestingly, a serine to arginine change at position 9 of the epitope abrogated clone recognition in one of the patients. This aa change is one factor that has been associated with a change from a nonsyncytium-inducing to a syncytium-inducing phenotype of HIV-1, raising the possibility that in HLA-B7-expressing patients, escape from this clonal CTL response and a change in viral phenotype may be linked. This study demonstrates that human CTL can be generated against sequences within the third variable loop of HIV-1 gp120. Because multiple vaccine strategies are based upon the V3 loop of HIV-1 gp120, this defined epitope can be exploited in determining the ability of certain vaccines to stimulate a CTL response in a select population of individuals.

Acute Disease↗
PubMed1994

Incidence of seroconversion for hepatitis C virus in chronic haemodialysis patients: a prospective study.

We conducted a prospective study in HD patients of our unit to evaluate the incidence of seroconversion for HCV in this high-risk group. Two hundred and thirty-five patients were observed during the average follow-up of 29.4 months: 183 were seronegative and 52 seropositive for anti-HCV antibodies at the start of the study. During the observation period two of 183 patients developed anti-HCV antibodies late in the study, while the other 181 patients remained seronegative throughout the observation period; anti-HCV antibodies persisted through the follow-up in the 52 HCV-positive patients at the beginning of the study. Our results showed a very low incidence of HCV seropositivity (0.44% per year) after implementation of our operative protocol including 'universal precautions' and other infection control procedures. Once infected, there is no disappearance rate of anti-HCV. The 4-RIBA results did not change during the follow-up period. Prevalence of HCV RNA by PCR technique was 41% (22 of 54) among anti-HCV-positive patients. Future investigations are warranted to clarify the exact route of transmission of HCV among HD patients and to reduce the rate of HCV transmission in this clinical setting.

Adolescent↗
PubMed1995

[Use of the B19 strain in the prevention of bovine brucellosis in northern Cameroon. Study of effect of the dose on seroconversion rate and duration in female zebu].

Four herds of zebus from northern Cameroon totalling 136 animals were vaccinated subcutaneously with the following doses of Brucella abortus strain 19: 5 x 10(9) colony-forming units (CFU), 10(9) CFU, 5 x 10(8) CFU and 10(7) CFU. Twenty-eight days after vaccination, the following seroconversion rates were observed respectively: 97.4, 96.2 84.2 and 73.3%. Of the 52 animals which could be tested subsequently including 39 over one year old on the vaccination day, only one showed antibodies 6 months after vaccination. The cost price of the strain 19 vaccine produced at the Boklé National Veterinary Laboratory was estimated to be 65 F CFA at the 10(9) CFU dose and 1,740 F CFA at the 5 x 10(10) CFU dose usually recommended. The use of the Buck 19 strain in the medical prophylaxis of bovine brucellosis in northern Cameroon is discussed.

Animals↗
PubMed1993

Six cases of seroconversion of human immunodeficient virus (HIV) antibody post-transfusion in HIV seronegative bloods.

Seroconversion of human immunodeficient virus (HIV)-antibody post blood transfusion has been reported (Jett et al, 1983; Cumming et al, 1989). We report here, six hematologic patients who became HIV-antibody positive after receiving HIV seronegative blood and blood components during their illness. There were three cases of acute non-lymphocytic leukemia, one thalassemia, one dyshemopoiesis and one hemophilia A. Thus, the risk of acquiring HIV infection from transfusion remains, despite the routine serological screening of donated blood by HIV ELISA tests. So the laboratory screening of blood should be improved by using more sensitive and specific antibody kits, including the use of HIV antigen testing, which have been reported to be useful in the diagnosis of patients with the early HIV infection.

Adolescent↗
PubMed1993

[Evaluation of seroconversion after voluntary vaccination against hepatitis B in students at the University of Lodz].

We have evaluated the results of the first action of voluntary vaccination against hepatitis B in the students of Medical University of Lódź using Energix-B vaccine (20 micrograms) in schedule 0, 1, 6 months. Few students applied for the vaccination: only 48.4% of persons planned for vaccination completed the schedule. Seroconversion rate (anti-HBs > 10u/l) in this group was 93.9%. Three doses of vaccine applied inconsistently with schedule resulted in the immunological response in 3 out of 4 students observed. Two doses of vaccine resulted in the effective response in 13 out of 16 students observed. One doses of vaccine proved to be ineffective. The blood tests performed prior to vaccination showed the presence of the HBV markers in 9.6% of students (HBsAg in 2.1% of persons and anti-HBs in 5.3/of persons).

Adult↗
PubMed1993

Human immunodeficiency virus seroconversion among intravenous drug users in- and out-of-treatment: an 18-month prospective follow-up.

Our objective was to determine the prevalence and incidence of human immunodeficiency virus (HIV) infection and related risk behaviors among opiate-abusing intravenous drug users (IVDUs) either in or out of methadone treatment. The subjects, 152 in-treatment and 103 out-of-treatment intravenous opiate users, were followed prospectively for 18 months. Behavioral and serologic assessments were made at 6-month intervals, with complete information available on 89% of the sample. Subjects were recruited from a single methadone maintenance program and the surrounding neighborhood in north-central Philadelphia. At baseline, the HIV seroprevalence rate for the total sample was 12%: 10% for the methadone-maintained group and 16% for the out-of-treatment group. Out-of-treatment subjects were injecting drugs, sharing needles, visiting shooting galleries, and practicing unsafe sex at significantly higher rates than in-treatment subjects. Follow-up of HIV-negative subjects over the next 18 months showed conversion rates of 3.5% for those who remained in methadone maintenance versus 22% for those who remained out of treatment. The sixfold difference in rate of seroconversion between the two groups suggests that although rapid transmission of HIV still occurs, opiate-abusing IVDUs who enter methadone treatment are significantly less likely to become infected. In contrast, those opiate addicts who do not enter treatment are at significantly higher risk of contracting and spreading the disease. Implications for developing additional risk interventions for out-of-treatment IVDUs are discussed.

Adult↗
PubMed1997

[Positive seroconversion syphilis in a patient with acute lymphocytic leukemia after allogeneic bone marrow transplantation].

An acute lymphocytic leukemia patient underwent allogeneic bone marrow transplantation (BMT) from a sibling who was serologically positive for syphilis. After the donor was administered antibiotic therapy, the titration of treponema pallidum hemagglutination (TPHA) decreased from x1260 to x320. Thereafter, the graft consisting of mononuclear cells was transplanted. TPHA of the recipient turned positive on day +63, but became negative 1.5 years after BMT. Although the cause of the seroconversion of TPHA seemed to be the contamination of treponema to the graft, the adoptive transfer could not be ruled out as an another possible cause.

Adult↗
PubMedDate not supplied

[The risk of seroconversion in surgeons of the hepatitis B, hepatitis C and human immunodeficiency viruses (in a specific surgical population)].

The prevalence of hepatitis B surface antigen (HBs Ag) and antibody to hepatitis C virus (HCV) and human immunodeficiency virus (HIV) was determined in the serum specimens of 288 patients treated surgically in the orthopaedic department of an urban public teaching hospital. The cumulative risk of HBV, HCV and HIV seroconversion for an orthopaedic surgeon during the surgical career span was calculated. We found that 1.4%, 3.1% and 1.7% of patients were seropositive for HBsAg, HCV antibody and HIV antibody, respectively. Seropositivity was neither associated with age nor with trauma, whereas male patients had a greater likelihood of seropositivity. Risk factor assessment did not prove to be discriminating in identifying which patients may pose a potential exposure risk. This study supports the concept of universal infection control precautions for orthopaedic surgeons regardless of the patients' risk factor or serologic status.

Adult↗
PubMed1998

Impact of HIV counselling and testing on HIV seroconversion and reported STD incidence among male factory workers in Harare, Zimbabwe.

OBJECTIVES: To assess the impact of HIV counselling and testing on HIV seroconversion and incidence of reported sexually transmitted diseases (STDs) among male factory workers in Harare, Zimbabwe. DESIGN: Prospective, observational study among men recruited to participate in a future workplace based AIDS prevention intervention. METHODS: Participants provided STD histories and blood for HIV antibody testing at enrolment and six month intervals during visits to factories. Participants received HIV test results, post test counselling, and free STD services at the project clinic. RESULTS: Between March 1993 and June 1995, 2,414 men were enrolled with 85% follow up. Overall HIV sero-incidence was 2.60 per 100 person-years; the incidence of reported STDs was 10.19 per 100 person-years. Men who obtained their HIV test results had significantly higher HIV sero-incidence and incidence of reported STDs compared to men who did not obtain their results (IRRs: 1.87, 3.47, respectively). Among men who obtained their HIV test results, a non-significant 40% decrease in HIV sero-incidence was observed after obtaining test results compared to before obtaining results (p = 0.18). The incidence of reported STDs, however, increased by 30% after obtaining HIV test results (p = 0.10). CONCLUSIONS: Decreased HIV sero-incidence in the face of increased reported STD incidence suggests that timely treatment of STDs may decrease the risk of acquiring HIV even in the absence of behaviour change. In populations with high rates of HIV and STDs, the greatest benefit of HIV counselling and testing may be achieved by simultaneously offering STD screening and treatment services.

AIDS Serodiagnosis↗
PubMed1992

Low seroconversion rates to measles vaccine among children in Nigeria.

The Nigerian Expanded Programme on Immunization (EPI) was assessed with particular reference to measles immunization. Of 150 children who received measles vaccine at the Institute of Child Health, University of Ibadan, Nigeria, 82 (54.7%) seroconverted. The immune response was directly related to the titre of the vaccines used. Vaccines whose titres were 10(-1) to 10(1.7) stimulated immune responses in 0-25% of vaccinees, those with titres in the range 10(-2.1) to 10(-2.5) stimulated responses in 12-47.6%, while those with titres of 10(-2.7) to 10(-3.4) stimulated responses in 87.5-100% of vaccinees. Only one of the vaccines used had a titre that met the minimum WHO required standard of log 10(-3) TCID50 at the point of vaccination.

Antibodies, Viral↗