Reduction of the diagnostic window in three cases of human immunodeficiency-1 subtype E primary infection with fourth-generation HIV screening assays.

BACKGROUND AND OBJECTIVES: The influence of genetic variability on the sensitivity of serological diagnosis of human immunodeficiency virus (HIV) infection has, to date, been poorly investigated. The aim of the present study was to assess whether fourth-generation assays for the combined detection of HIV antigen and antibodies to HIV (anti-HIV) permit a reduction of the diagnostic window in comparison to third-generation antibody enzyme immunoassays (EIAs), which so far have shown a poor sensitivity for detection of HIV-1 non-subtype B primary infections. MATERIALS AND METHODS: Three patients with primary HIV-1 subtype E (CRF01-AE) infection were tested with different third- and fourth-generation assays, stand-alone HIV antigen (Ag) EIAs and reverse transcription-polymerase chain reaction (RT-PCR). Additionally, virus lysates from HIV-1 Group M and O and HIV-2, at concentrations of p24 Ag close to the detection limit of licensed HIV Ag EIAs, were investigated with fourth-generation EIAs and HIV Ag EIAs. RESULTS: In the first blood donor, the most sensitive fourth-generation assay detected HIV-1 infection 11 days earlier than five of the eight third-generation antibody assays. Fourth-generation EIAs, with a high sensitivity for HIV antigen, detected HIV-1 subtype E infection simultaneously or 4 days later than HIV-1 RT-PCR on pooled samples. Low concentrations of virus lysates of different HIV-1 subtypes A-H and group O, tested positive with fourth-generation EIAs, with a high sensitivity of the antigen-detection module. CONCLUSIONS: Fourth-generation EIAs, especially those with a high sensitivity for HIV-1 p24 antigen, reduce the diagnostic window for primary HIV-1 subtype E infection in comparison with third-generation antibody-screening assays. These preliminary data from seroconversions and virus lysates indicate that the genetic diversity of HIV-1 does not represent a major challenge for the most sensitive EIAs of this new assay generation.

Susceptibility to hepatitis A virus infection among chronic liver disease patients and healthy blood donors in Thailand.

Due to improvements in socio-economic and sanitation conditions, Thailand has undergone a change from hyperendemicity to intermediate endemicity for hepatitis A virus infection, leaving a large part of the adult population without immunity. At the same time, the country is still highly endemic for hepatitis B and especially in the northeast, hepatitis C virus infection both of which when acquired during infancy or early childhood exhibit a strong tendency to turn towards chronic liver disease, although in particular with hepatitis B virus the asymptomatic carrier state is also rather common. As no cross-immunity exists between any of these viruses, double or triple infections do occur, a situation where previously acquired immunity to HAV becomes crucial as double infections have been shown to take a more severe or even fatal course. In the present study, we investigated 820 HBV- and/or HCV-related chronic liver disease (CLD) patients and 195 blood donors, both groups divided by 10-year age intervals, for the prevalence of anti-HAV. The results showed the same age dependence of immunity for all groups tested as can be expected for an area of intermediate endemicity, in that approximately 50% of those between 21 and 30 years of age had acquired anti-HAV. These findings indicate the immune response to HAV infection not to be altered by chronic infection with either HBV or HCV. Hence, vaccination against HAV should be considered, particularly in anti-HAV-negative patients with CLD.

Detection of HIV-1 window period infection in blood donors using borderline anti-HIV results, HIV-1 proviral DNA PCR, and HIV-1 antigen test.

Prevention of transmission of HIV-1 via blood transfusion has been carried out by the National Blood Center by screening donated blood with anti-HIV and HIV antigen tests. To increase the safety measure, detection of proviral DNA by PCR has been proposed; however, it was impractical to test all samples by PCR. From August 1994 to September 1995, there were 296,169 blood donors with 0.32 per cent prevalence of anti-HIV positive. From these donors, 153 samples of which the anti-HIV enzyme immunoassay optical density (OD) between cutoff and 80 per cent of cutoff value (borderline results) were selected for PCR testing. One out of 153 borderline cases showed positive by PCR test for HIV-1 proviral DNA. However, this case was also positive by HIV antigen test. Therefore, most of the samples with borderline anti-HIV results were true negative for HIV infection. On the other hand, there were 8 HIV antigen positive samples which had anti-HIV OD below the borderline value determined in this study. This finding confirmed the necessity of using both the anti-HIV and HIV antigen tests for screening of donated blood.

Evolutionary analysis of variants of hepatitis C virus found in South-East Asia: comparison with classifications based upon sequence similarity.

Variants of hepatitis C virus (HCV) have been classified by nucleotide sequence comparisons in different regions of the genome. Many investigators have defined the ranges of sequence similarity values or evolutionary distances corresponding to divisions of HCV into types, subtypes and isolates. Using these criteria, novel variants of HCV from Vietnam, Thailand and Indonesia have been classified as types 7, 8, 9, 10 and 11, many of which can be further subdivided into between two to four subtypes. In this study, this distance-based method of virus classification was compared with phylogenetic analysis and statistical measures to establish the confidence of the groupings. Using bootstrap resampling of phylogenetic trees in several subgenomic regions (core, E1, NS5) and with complete genomic sequences, we found that one set of novel HCV variants ('types 7, 8, 9 and 11') consistently grouped together into a single clade that also contained type 6a, while 'type 10a' grouped with type 3. In contrast, no robust higher-order groupings were observed between any of the other five previously described HCV genotypes (types 1-5). In each subgenomic region, the distribution of pairwise distances between members of the type 6 clade were consistently bi-modal and therefore provided no justification for classification of these variants into the three proposed categories (type, subtype, isolate). Based on these results, we propose that a more useful classification would regard all these variants as subtypes of type 6 or type 3, even though the level of sequence diversity within the clade was greater than observed for other genotypes. Classification by phylogenetic relatedness rules out simple sequence similarity measurements as a method for assigning HCV genotypes, but provides a more appropriate description of the evolutionary and epidemiological history of a virus.

Transfusion-transmitted AIDS with blood negative for anti-HIV and HIV-antigen.

A four-year-old boy who was diagnosed with Glanzmann's thrombasthenia received supportive treatment and desmopressin for his bleeding episodes. He seldom received blood components, except for platelet concentrates, due to severe bleeding. He was exposed to 18 routine donors and 2 plateletpheresis donors who were negative for human immunodeficiency virus (HIV) antigen and anti-HIV upon screening. At the age of 3 years and 9 months (4.5 months after the transfusion of platelet concentrate), he developed full-blown AIDS and died from circulatory failure 3 months later. The source of HIV transmission was identified as I donor who developed anti-HIV 3 months after the last donation. The rather short incubation time of AIDS in this case was attributed to a large inoculum of HIV virus in the 'window period' of infectivity of the newly infected donor. This case illustrates transfusion-transmitted HIV leading to AIDS, even though HIV antigen and anti-HIV screening tests were negative.

Epidemiologic characteristics of blood donors with antibody to human immunodeficiency virus: Thailand.

Of 782,190 volunteer blood donors in Bangkok and nearby areas, who were screened for infection with human immunodeficiency type 1 (HIV-1) from January 1988 through December 1992, 3,219 tested positive on both enzyme immuno assay and Western blot assay. The identification variables of the donor were collected. The majority of HIV seropositive blood donors were male. The average age (median) of HIV seropositive was 26-29 years all through 1988-2992. The prevalence of HIV seropositive in male donors was higher than that in females. HIV seropositivity was confirmed in blood donations from first-time male donors in this study during 1988-1992. This rate has increased progressively from 0.87/1,000 in 1988 to 15.95/1,000 in 1992 with much higher rates in repeat donors. The repeat male donors increased from 0.77/1,000 in 1988 to 5.26/1,000 in 1991 and since then showed a decreased rate to 3.93/1,000 in 1992. Female donors were infected with HIV more frequently with the prevalence by sex ratio M:F rising from 27:1 in 1988 to 6.6:1 in 1992. Comparing the seropositive rate between first time and repeat female donors, the results showed an increase in rate from 0.11/1,000 in 1990 to 2.02/1,000 in 1992, but essentially the same rate in report donors. A majority of HIV seropositive blood donors (1990-1992) lived in Bangkok (42-49%) and among those who lived in one eastern province (Samut Prakan), 90-93% lived in the industrial areas. Of those who lived in Chon Buri Province, 73-88% lived in Sattaheep District, which is a naval base.

Transmission of HIV infection by seronegative blood in Thailand.

In Thailand, the prevalence of HIV infection in the general population and in donor blood (DB) has sharply increased since 1987. The HIV seropositive rate in DB was increased from 0.0065 per cent in 1987 to 0.95 per cent in 1993 (150 times in 6 years). Heterosexual transmission is the major route of spreading. Therefore, HIV seronegative blood (SNB) poses significant hazard to the recipients because of the risk of viraemia during the window period of early HIV infection. In Thailand HIV Ab screening in all units of blood was started in 1987 and was compulsory nationwide in early 1989. Donor self exclusion (DSE) has been implemented since 1990. It is not fully effective in the prevention of transfusion associated AIDS (TAA) because of many limiting factors. However, DSE should be promoted to practice in every blood bank particularly those that can not do HIV Ag screening. During 1990-1992, there were 30 reported cases of TAA by SNB. The study of risk figure (HIV Ag positive-neutralization with HIV Ab negative) in DB was 1:3,400 and 1:10,000 in two reports in 1991. Under all these circumstances, the national AIDS committee has documented the policy to do HIV Ag screening in every unit of blood from August 1991 and allocated a 10 million baht budget (year 1992) for Ag testing. Several hospitals and NBC reported the risk figures which varied from 1:3,400 to 1:25,000. A certain amount of blood is processed to 2-4 blood components given to 2-4 patients which will increase the number of TAA by SNB.(ABSTRACT TRUNCATED AT 250 WORDS)

PIP: In Thailand, the human immunodeficiency virus (HIV) seropositivity rate in donated blood increased 150 times from 1987 to 1993, from 0.0065% to 0.95%. Although the National Blood Center and large hospitals initiated HIV antibody screening of all blood in 1987, HIV seronegative blood can pose a serious hazard to recipients because of the risk of viremia during the window period of early HIV infection. Transfusion-associated acquired immunodeficiency syndrome (AIDS) from seronegative blood was first reported in Thailand in 1990 in three thalassemic children. To reduce this risk, HIV P24 Ag screening has been mandatory since 1990 and is estimated to prevent about 180 cases of transfusion-associated HIV transmission from seronegative blood per year. Less effective, yet recommended, is donor self-exclusion. Other preventive measures recommended include exclusion of donors from high-risk groups, public education, sensitive and early detection of IgM antibodies, promotion of autologous blood transfusion, and the use of blood substitutes or blood stimulating factors.

HIV infection after autologous bone marrow transplantation despite HIV-antibody and HIV-antigen screening.

We report a 41-year-old woman who underwent ABMT for non-Hodgkin's lymphoma during her third CR. Her post-transplant course was complicated by interstitial pneumonitis, hemorrhagic cystitis, cytopenia and episodes of infection from herpes zoster virus and Staphylococcus aureus. She required prolonged blood product support and was later found to be seropositive for anti-HIV on day +191 despite HIV-antibody and HIV-antigen screening of blood donors.

Evaluation of a 2-minute anti-human immunodeficiency virus (HIV) test using the autologous erythrocyte agglutination technique with populations differing in HIV prevalence.

A total of 1,800 blood specimens (1,000 from healthy blood donors, 300 from patients with sexually transmitted disease, and 500 from intravenous drug users) were simultaneously tested with anti-human immunodeficiency virus enzyme-linked immunosorbent assay (ELISA) kits and a newly developed 2-min test for anti-human immunodeficiency virus based on the principle of autologous erythrocyte agglutination (AGEN Biomedical Limited). We found that AGEN's rapid test was as sensitive and specific as the other ELISA kits.

Risk of transfusion associated AIDS by seronegative blood in Thailand: a multicenter report.

Prevention of transfusion associated AIDS (TAA) in Thailand began in 1986 when the HIV infection started to be sharply increased among the general population. The retrospective anti-HIV screening in various blood donor populations by The National Blood Center (NBC) revealed a seroconverted prisoner. Then the use of prisoners, prisoners' blood was not recommended from 1986. In April 1987, the first case of TAA was disclosed. Five months later, anti-HIV screening in all units of blood was firstly introduced at Ramathibodi Hospital (RH) and NBC. From 1989, anti-HIV screening in all units of blood is mandatory nationwide by Ministry of Public Health. Despite the anti-HIV screening, TAA cases transmitted by seronegative blood were gradually reported. Among many Medical Centers, there were 9 and 18 cases of TAA recorded from Chiang Mai and Bangkok areas respectively, since 1985. In addition, several new seroconverters were observed among voluntary blood donors. All of this evidence indicates the existence of blood donation during the early stage of infection, the so-called "window period". At present, HIV-P24 antigen ELISA seems to be the only available technique for mass screening. In 1990, NBC successfully performed a retrospective study on HIV-Ag ELISA screening by obtaining the prevalence of 1/10,000 units of blood. At the same period of time, in RH prospective study, a unit of blood with HIV-Ag only was detected when 3432 units of blood were screened. The HIV-Ag ELISA screening was then performed on every unit of blood routinely since Aug 12, 1991 at RH.(ABSTRACT TRUNCATED AT 250 WORDS)

Trend study on HBsAg prevalence in Thai voluntary blood donors.

In 1973, the prevalence of HBsAg positive individuals was 9.33% in new army recruit blood donors and 8.28% in the general population (CIEP). The hepatitis B vaccine, which was introduced to use in Thailand in 1985, seems to be effective in reducing the prevalence of hepatitis B carriers year after year. In 1991, the prevalence of HBsAg in new blood donors (74,530) was 6.45% (RPHA). However, it was still relatively high at 8.38% in new army recruit blood donors, while in the general population it had decreased to 6.75%. The data suggested that carriers were more likely to be found in new army recruit blood donors, because most of them are from lower socioeconomic groups, less well educated, from rural areas and sexually active. Therefore, the immunization against hepatitis B must be considered for this high risk group in order to reduce the number of hepatitis B carriers.