Are seroepidemiological surveys for human immunodeficiency virus infection based on tests on pools of serum specimens accurate and cost-effective?

Serum specimens (n = 17668) from UK antenatal patients in the Thames Regions were tested by Wellcozyme HIV 1/2 EIA singly and in pools of 6, 12 and 24: 35 (0.2%, 1 in 505) were confirmed as anti-HIV positive. The pools of 12 were also tested for anti-HIV 1/2 by IAF Biochem, Behring and Diagnostics Pasteur EIAs. All 35 positive specimens were easily detectable after pooling in groups of 12. The false positive rate for Wellcozyme was nearly halved compared with individual testing (1 in 309 false positive compared with 1 in 174). For the other assays false positive rates on pools of 12 were: IAF Biochem 1 in 193, Behring 1 in 140, Diagnostics Pasteur 1 in 1547. Twenty-two known anti-HIV 2-positive sera were detected by all four EIAs when diluted as in pools of 6 and 12, but by only three EIAs in pools of 24 and 48. Pooling in groups of 6 did not seem to delay detection of HIV 1 seroconversion, but pooling in groups of 12, 24 and 48 might delay it by 1, 2 and 3 weeks respectively. For this study the effect of pooling in groups of 12 would have been a reagent saving of 87-91% and a labour saving of about 50%. Because of the low HIV incidence and rarity of specimens collected around seroconversion in UK, little, if any, loss of sensitivity would result from it. Pooling in groups of 12 has therefore been chosen for the screening of anonymous antenatal specimens in the UK.     

COMPARISON of FOUR LATEX AGGLUTINATION KITS to RAPIDLY IDENTIFY LANCEFIELD GROUP D ENTEROCOCCI and FECAL STREPTOCOCCI

Enterococci isolated from water (50 strains), clinical material (50 strains), pork products (25 strains), and other foods (25 strains) as well as 50 known strains were used to compare the abilities of four latex streptococcal grouping kits to correctly identify group D isolates. the Streptex kit (Wellcome Diagnostics) was 98.5% accurate and easiest to interpret. the Slidex Strepto kit (Vitek Systems) and Strepslide kit (NCS Diagnostics) also were acceptable; they were 96.5% and 96.0% accurate, respectively. When the Bacto Strep Grouping kit (Difco Laboratories) was used, 99% of the group D isolates were positive for both group D and group B, including enterococcal strains that are group D-negative.     

Comparative methods of detecting HbsAg in chronic glomerulonephritis patients in Nigeria

Abstract A comparative evaluation of the enzyme-linked immunosorbent assay (Elisa), passive haemagglutination (PHA) and counterimmunoelectrophoresis (CIE) methods were carried out. Approx. 6% of control samples were positive with the Elisa assay, while the values for Behring Institute (BI) passive haemagglutination, Wellcome Research Laboratory (WRL) passive haemagglutination and CIE were 2.7%, 2.2% and 3.3%, respectively. The above data contrast with values of 21.3%, 10.6, 10.3 and 12.3 obtained in sera from chronic glomerulonephritis patients.
Our observation suggests that HbsAg may be associated with chronic glomerulonephritis.     

应用转化细胞分泌的乙型肝炎病毒e抗原检测人血清中的乙型肝炎病毒e抗体

应用乙型肝炎病毒核心抗原基因转化的小鼠L细胞分泌的乙型肝炎病毒e抗原,采用ELISA法与Abbott公司抗-HBe EIA诊断盒平行比较,检测了31份抗-HBe阳性和19份抗-HBe阴性的人血清,结果完全相符。经多次重复试验,本法的OD490nm值的误差不超过8％。OD490nm值与血清稀释度之间呈直线关系。细胞培养液不经纯化即可应用,一般做1:4稀释。细胞分泌的抗原无感染性,价格低廉,不会因结合人血清蛋白而产生非特异性反应。因此比一般诊断盒中所用的人血清HBeAg有很大的优越性。     

Point of Care Tuberculosis Sero-Diagnosis Kit for Wild Animals: Combination of Proteins for Improving the Diagnostic Sensitivity and Specificity

Tuberculosis is a significant problem globally for domestic animals as well as captive and free ranging wild life. Rapid point of care (POC) serology kits are well suited for the diagnosis of TB in wild animals. However, wild animals are invariably exposed to environmental non-pathogenic mycobacterium species with the development of cross reacting antibodies. In the present study, POC TB diagnosis kit was developed using a combination of pathogenic Mycobacteria specific recombinant antigens and purified protein derivatives of pathogenic and non-pathogenic Mycobacteria. To benchmark the TB antibody detection kit, particularly in respect to specificity which could not be determined in wildlife due to the lack of samples from confirmed uninfected animals, we first tested well-characterized sera from 100 M. bovis infected and 100 uninfected cattle. Then we investigated the kit’s performance using sera samples from wildlife, namely Sloth Bears (n = 74), Elephants (n = 9), Cervidae (n = 14), Felidae (n = 21), Cape buffalo (n = 2), Wild bear (n = 1) and Wild dog (n = 1).In cattle, a sensitivity of 81% and a specificity of 90% were obtained. The diagnostic sensitivity of the kit was 94% when the kit was tested using known TB positive sloth bear sera samples. 47.4% of the in-contact sloth bears turned seropositive using the rapid POC TB diagnostic kit. Seropositivity in other wild animals was 25% when the sera samples were tested using the kit. A point of care TB sero-diagnostic kit with the combination of proteins was developed and the kit was validated using the sera samples of wild animals.     

Comparative evaluation of methods for detecting HBsAg in sera

The results of the analysis of 1209 serum samples, made with a view to detecting those containing HBsAg, are presented. This analysis was made by the radioimmunoassay (RIA) on a polyethylene film, by the standard RIA technique with the use of a diagnostic kit obtained from Abbott Laboratories (USA) and by the passive hemagglutination (PHA) test. The RIA film technique was found to have the sensitivity of about 2 ng/ml HBsAg, which is similar to the sensitivity of the kit from Abbott Laboratories and exceeds the sensitivity of the PHA test approximately 50-fold. The percentage of detected HBsAg-positive sera, yielded by analysis with the use of the RIA film technique and the standard RIA technique, is the same. The RIA technique make it possible to detect more positive sera than the PHA test by about 2.5%.     

The use of commercial immunoenzyme and latex preparations for the demonstration of human rotavirus antigens

The results of using enzyme immunoassay and latex preparations for the diagnosis of rotavirus gastroenteritis are presented. High effectiveness of the enzyme immunoassay system developed in the USSR with latex diagnostic agents, such as Rotalex (Orion Diagnostica, Finland), Slidex Rota Kit (BioMérieux, France), The Wellcome Rotavirus Latex Kit (Wellcome Foundation Ltd., Great Britain), 48-63% and 21-41% respectively, has been noted. The results of the comparison of the system developed in the USSR with Wellcozyme Rotavirus, an enzyme immunoassay system manufactured by Wellcome Foundation Ltd. (Great Britain), are practically comparable. The results of the block test and the confirmation test used for control indicate that the Soviet preparation is specific. Materials on the practical evaluation of the assay system at health institutions are presented. Good prospects for the use of this system in the diagnosis of rotavirus gastroenteritis, as well as in the realization of epidemiological surveillance on this infection, are substantiated.     

Infectious disease screening of blood specimens collected post-mortem provides comparable results to pre-mortem specimens

Serology assays for standard screening are optimised for use with sera collected from living adults and children. Because of potential changes in the vascular compartments after death, methods used for screening sera from cadaveric organ donors need to be validated before testing these specimens. Serum was separated from blood collected from cadaveric donors within 24?h of death and biochemical parameters measured to detect dilution of protein and haemolysis. In order to demonstrate if any inhibitors that might interfere with the assays were present, pre and post-mortem specimens were spiked with aliquots of human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV), human T-cell Lymphotropic Virus (HTLV) and T. pallidum-positive sera. Comparison of serum from living subjects with serum obtained post-mortem showed that while the concentration of total protein decreased, concentrations of albumin, immunoglobulin G (IgG) and immunoglobulin M (IgM) remained unchanged. The degree of haemolysis, as measured by free haemoglobin, was within the limits accepted for the Architect analyser. Spiking of pre- and post-mortem specimens with aliquots of HIV, HCV, HBV, HTLV and T. pallidum-positive sera showed no statistical difference in the signal between pre-mortem and post-mortem results when tested on the Abbott Architect analyser. Positive results were obtained in each of a further nine subjects who had tested positive for HIV (n?=?1), HCV (n?=?8), HBV (n?=?1) on pre-mortem serological testing. These findings suggest that the sensitivity of the Abbott Architect serological screening tests is not significantly affected in specimens collected within 24?h of the cessation of life.     

Evaluation of the Auxacolor system for the identification of clinical yeast isolates

In the last decade the number of systemic yeast infections has increased significantly. Although Candida albicans is the most frequently isolated yeast from clinical specimens, the emergence of non-albicans species has clearly been a recent concern. As a consequence, there is a greater need for rapid and accurate methods for yeast identification. The aim of this study was to evaluate the performance of the AUXACOLOR system (Sanofi Diagnostics Pasteur) for the identification of clinically relevant yeasts, as compared with the conventional method. Yeast isolates (n = 97) belonging to 12 species were identified by the commercial system and the classic method. Correct identifications were obtained by using AUXACOLOR system in 79.4% of the isolates tested. Misidentification occurred in 5.2% of the strains and 15.5% were not identified due to a failure in the manufacturer's data base. In order to improve its accuracy, there is a need for expanding the database or revamping the tests included in the system. This revised version was published online in June 2006 with corrections to the Cover Date.     

Evaluation of five hepatitis C virus screening tests and two supplemental assays: performance when testing sera from sexually transmitted diseases clinic attendees in the USA

The performances of five screening tests (recombinant peptide-based first and second generation tests from Abbott and Ortho, and a synthetic peptide-based test from Biochem Immunosystems) and two supplemental tests: recombinant peptide- based, Abbott neutralization test and Chiron second generation recombinant immunoblot assay (RIBA 2), were evaluated for their ability to detect hepatitis C virus (HCV) antibodies in a population of 276 individuals attending a sexually transmitted diseases (STD) clinic in the USA. Although the five screening tests produced a variable number (35-62) of repeatedly reactive samples, only 13% (36/276) were classified as true positives by the supplemental tests. Thirty-four of the 36 were reactive by all screening tests and 32 of the true positives were reactive by both supplemental tests, while 2 did not neutralize but were reactive in the RIBA 2 test. Of the remaining 2 of the true positives which were discordant by several of the screening assays, 1 was confirmed by both supplemental assays but the other required a chemiluminescent enhancement technique to show positivity in RIBA 2. The sensitivities of the first and second generation Abbott and Ortho tests ranged from 97% to 100% and that of the Biochem test was 94%. The specificities of these tests ranged from 89.2% to 99.6%. The second generation Ortho test presented 9.4% (26/276) false positives. The use of second generation Ortho as a screening test would lead to an excessive number of confirmatory false positives. the positive predictive values of the screening tests ranged from 58.1% to 97.1%. Although the synthetic peptide based Biochem test exhibited the best overall indices, the presence of 2 false negative results would prevent its use as a singular screening test. Nevertheless its high specificity may lend itself to be used as a second screening test before confirmatory testing with RIBA 2.     

A comparative study of the sensitivity and specific activity of an immunoenzyme test system for determining class-M antibodies to the hepatitis A virus

The diagnostic value of the first experimental production batches of assay kit "DIAGN-A-HEP", produced at the Institute of Poliomyelitis and Viral Encephalitides (USSR Acad. Med. Sci.) and intended for the determination of IgM to hepatitis A virus (HAV) in the enzyme immunoassay (EIA), has been studied in comparison with that of the internationally known and widely approved commercial EIA system "HAVAB-MEIA" for the determination of antibodies to HAV (the product of Abbott, USA). The study has revealed that the EIA kit "DIAGN-A-HEP" is highly sensitive and specific, and the diagnostic value of this kit is not inferior to that of the commercial assay system "HAVAB-MEIA". On the basis of this study the use of the EIA kits "DIAGN-A-HEP" in medical practice has been allowed by the decree of the Ministry of Health of the USSR.     

HIV-2 antibody testing of blood donors with doubtful immunoblot results for HIV-1

Antibodies against human immunodeficiency virus type-1 (HIV-1) in samples from blood donors are commonly detected by various enzyme-linked immunosorbent assays (ELISA) and by confirmatory tests, e.g., "Western blot" or immunofluorescence tests. Immunoblot reactivity, which is directed only towards the HIV-1 core proteins p 18, p 24 and p 55, may represent false-positive reactions. Out of 125,000 blood donations, 140 were repeatably HIV-1 antibody reactive by ELISA; of these, 20 were doubtful positive sera with isolated p 18 and/or p 24 bands in the HIV-1 confirmatory assay. Antibodies to HIV-2 are known to cross-react with these HIV-1 core proteins. We therefore assayed the 20 sera by immunofluorescence and immunoblotting for the presence of antibodies to HIV-2. None of these doubtful HIV-1 antibody positive blood donor sera was found to have antibodies to HIV-2.     

Development of a western blotting assay to discriminate Brucella spp. and Yersinia enterocolitica O:9 infections in sheep

Outer membrane proteins (OMPs) of Rev-1 strain of Brucella melitensis were used in a Western blotting assay for the serological diagnosis of brucellosis in ovine sera. Fifty-four sheep sera were tested and divided into the following groups: Group A) n. 9 samples from one sheep that had been experimentally infected with Y. enterocolitica O:9; Group B) n. 10 samples collected from sheep infected with Brucella melitensis and 1 sample from a sheep vaccinated with the Rev 1 strain; Group C) n. 10 samples collected in "officially brucellosis-free" herds; Group D) n. 12 samples classified as "suspicious"; Group E) n. 12 samples classified as "positive". Antibodies were detected by routine tests performed for the diagnosis of brucellosis in serum samples of the sheep infected with Y. enterocolitica O:9 after the 2nd week post infection. In the WB assay, sera of group B recognised a 17 kDa protein, whereas sera of groups A, and D and 9 out of 12 of group E exhibited no reactivity to this protein. The results obtained encourage the use of the WB assay as a confirmatory test for the diagnosis of brucellosis.     

国产放射免疫试剂与Abbott放射免疫试剂检测乙型肝炎病毒感染指征的比较

本文报告了国产乙型肝炎病毒(HBV)RIA和Abbott RIA诊断试剂盒检测质量的比较研究。表明两试剂滴定HBsAg、抗-HBs、抗-HBc阳性血清的敏感性相似,抗-HBs mIU/ml定量检测结果相符。证明国产RIA试剂质量是可靠的。但是,国产试剂S/N值曲线的陡度和标本的阳性检出率较Abbott试剂为高,可能与试剂出厂后周转期短有关。适当提高国产试剂阳性判定标准后,与Abbott试剂的检测符合率可达90％以上。     

Comparative Seroepidemiologic Analysis of <Emphasis Type="Italic">Chlamydophila Pneumoniae</Emphasis> Infection using Microimmunofluorescence,Enzyme Immunoassay and Neutralization Test: Implications for Serodiagnosis

A seroepidemiologic study using the microimmunofluorescence (MIF) technique was conducted to determine the prevalence of Chlamydophila pneumoniae IgG antibodies among 205 healthy Singapore university undergraduates using the MRL Diagnostics MIF test kit. The overall seroprevalence was 35.1% with significantly higher seropositivity rates among males than females (48.2 vs. 18.7%, P < 0.001). A comparative study using the Labsystems MIF test kit was conducted on sera from 192 students. Using the MRL MIF test as the reference, the sensitivity and specificity of Labsystems MIF test were 92.6 and 87.9%, respectively. A total of 78 samples comprising 15 MIF-negative and 63 MIF-positive samples were also tested for complement-independent neutralizing antibodies in vitro. All the 78 samples and 11 additional MIF-negative samples were also tested for IgM, IgG and IgA against C. pneumoniae by enzyme immunoassay (EIA) using the Labsystems EIA test kit. None of these 89 samples were seropositive for IgM. The percentages of IgG and IgA seropositivity increased with increasing grades of MIF-positivity. Among the IgG seropositive samples, 69.1% were also positive for IgA, suggesting that a high proportion of infected individuals also had IgA antibodies denoting chronicity. Neutralizing antibodies were detected in 22.2% of MIF-positive sera, but only in 6.7% of MIF-negative sera. 26.4 and 34.2% of samples which were IgG and IgA seropositive respectively also exhibited neutralizing activity. The percentages of MIF-positive sera with neutralizing activity increased with the grade of MIF positivity, i.e. 0% (1+), 7.1% (2+), 18.8% (3+), and 63.6% (4+). High-grade MIF positivity (particularly with MRL MIF kits) may represent a useful serologic marker of predictive value for neutralizing activity.     

Comparison of two microimmunofluorescence tests for detecting antibodies to Chlamydia pneumoniae

Two microimmunofluorescence (MIF) tests were compared for detection of antibodies to Chlamydia pneumoniae: the microimmunofluorescence of Washington University and the microimmunofluorescence of Chlamydia Serofia. Concordant positive results at the same dilution were observed for IgG in 37.33% of sera tested and concordant negative results were found in 44%. Variations of one fold dilution were observed in 36 sera. Extensive variations (2-3 two-fold dilutions) in the numeric titer values were observed in 20 serum samples with titers of antibody generally higher in the Chlamydia Serofia MIF than in the Washington MIF, resulting in a diagnosis of current infection in three patients. IgM were found with both methods only in one patient. The discrepancies observed may be due to several factors including the different TWAR strain used as antigen in the two tests and the dilution of the FITC-labelled conjugated anti-human IgG.We think that MIF serology may also be influenced by the type of response of the host that may depend on the "local strain" of C. pneumoniae that may express different antigens or in different amounts in comparison with the strains used by the commercial kit.     

The Eiken Latex test for detection of a cryptococcal antigen in cryptococcosis

A latex agglutination test for cryptococcal antigen, the Eiken Latex test (Eiken, Tokyo, Japan), was compared with a monoclonal antibody-based agglutination assay, Pastorex^® Cryptococcus (Diagnostics Pasteur, Marneur-la-Coquette, France). In a murine model of disseminated cryptococcosis, the kinetics of the antigen titers by the Eiken Latex were similar to those by the Pastorex^® Cryptococcus, but sensitivity was much higher. In HIV-negative patients with pulmonary cryptococcosis, a cryptococcal antigen was detected in 6 of 10 patients by the Eiken Latex test and in only 3 of those patients by the Pastorex^® Cryptococcus. The results indicate that the Eiken Latex is more sensitive for the detection of the cryptococcal antigen, even in non-disseminated cryptococcosis. The sensitivity and specificity of the Eiken Latex were examined using 195 sera from 25 patients with pulmonary cryptococcosis and 170 patients with non-cryptococcosis. The cutoff value of 1:8 showed a sensitivity of 76% (19/25) and a specificity of 98.9% (168/170).     

Comparison of three ELISA kits for the differentiation of foot-and-mouth disease virus-infected from vaccinated animals

A study was performed to validate 3 FMDV 3ABC-I-ELISA kits developed in China for the differentiation of FMDV infected and vaccinated animals. Sets of sera from naive and vaccinated cattle as well as from cattle that had been infected were tested for antibodies against nonstructural proteins (NSPs) of FMDV by commercial diagnosis kits, Ceditest® FMDV-NS (Ceditest® kit), UBI® FMDV NONSTRUCTURAL PROTEIN ELISA DIRECTION INSERT (UBI® kit) and a FMDV 3ABC-I-ELISA kit developed at the Lanzhou Veterinary Research Institute. The test parameters (sensitivity and specificity) of the three kits were determined, and the result obtained from FMD 3ABC-I-ELISA kit was compared with that obtained from two foreign kits. The results indicated that the coincidence rate between the FMDV 3ABC-I-ELISA and Ceditest® kits was 98.05%, and the coincidence rate between the FMDV 3ABC-I-ELISA and UBI® kits was 94.4%; the sensitivity of both Ceditest® and FMDV 3ABC-I-ELISA kit was 100%. However, the sensitivity of the UBI® kit was only 81.8%. With sera from naive or vaccinated non-infected animals, the specificity of all tests exceeded 90%.     

Comparison of Three ELISA Kits for the Differentiation of Foot-and-mouth Disease Virus-infected from Vaccinated Animals

A study was performed to validate 3 FMDV 3ABC-I-ELISA kits developed in China for the differentiation of FMDV infected and vaccinated animals.Sets of sera from naive and vaccinated cattle as well as from cattle that had been infected were tested for antibodies against nonstructural proteins (NSPs) of FMDV by commercial diagnosis kits,Ceditest(R)FMDV-NS (Ceditest(R) kit),UBI(R) FMDV NONSTRUCTURAL PROTEIN ELISA DIRECTION INSERT (UBI(R) kit) and a FMDV 3ABC-I-ELISA kitdeveloped at the Lanzhou Veterinary Research Institute.The test parameters (sensitivity and specificity) of the three kits were determined,and the result obtained from FMD 3ABC-I-ELISA kit was compared with that obtained from two foreign kits.The results indicated that the coincidence rate between the FMDV 3ABC-I-ELISA and Ceditest(R) kits was 98.05%,and the coincidence rate between the FMDV 3ABC-I-ELISA and UBI(R) kits was 94.4%; the sensitivity of both Ceditest(R) and FMDV 3ABC-I-ELISA kit was 100%.However,the sensitivity of the UBI(R) kit was only 81.8%.With sera from naive or vaccinated non-infected animals,the specificity of all tests exceeded 90%.