Rapid assay for simultaneous detection and differentiation of immunoglobulin G antibodies to human immunodeficiency virus type 1 (HIV-1) group M, HIV-1 group O, and HIV-2

Protein glycosylation in urine as a biomarker of diseases

Human body fluids have become an indispensable resource for clinical research, diagnosis and prognosis. Urine is widely used to discover disease-specific glycoprotein biomarkers because of its recurrently non-invasive collection and disease-indicating properties. While urine is an unstable fluid in that its composition changes with ingested nutrients and further as it is excreted through micturition, urinary proteins are more stable and their abnormal glycosylation is associated with diseases. It is known that aberrant glycosylation can define tumor malignancy and indicate disease initiation and progression. However, a thorough and translational survey of urinary glycosylation in diseases has not been performed. In this article, we evaluate the clinical applications of urine, introduce methods for urine glycosylation analysis, and discuss urine glycoprotein biomarkers. We emphasize the importance of mining urinary glycoproteins and searching for disease-specific glycosylation in various diseases (including cancer, neurodegenerative diseases, diabetes, and viral infections). With advances in mass spectrometry-based glycomics/glycoproteomics/glycopeptidomics, characterization of disease-specific glycosylation will optimistically lead to the discovery of disease-related urinary biomarkers with better sensitivity and specificity in the near future.

Urinary immunoglobulins in viral diagnosis: An overview

Antibody detection by serological methods gained a lot of interest in recent years and has become the backbone of virological diagnosis. Despite the detection of all five classes of immunoglobulins in urine, not much attention has been paid to the use of urine as a diagnostic sample to detect viral antibodies. Unlike venipuncture, this non-invasive mode of sample collection can help cover all age groups, especially paediatric and old age patients, where blood collection is difficult. Using urine as a sample is also economical and involves lesser risk in sample collection. The antibodies are found to be stable in urine at room temperature for a prolonged period, which makes the sample transport management easier as well. A few recent studies, have also shown that the detection limit of antibodies in urine is at par with serum or other clinical material. So, the ease in sample collection, availability of samples in large quantity and stability of immunoglobulins in urine for prolonged periods can make urine an ideal sample for viral diagnosis.

Lateral flow test strip based on colloidal selenium immunoassay for rapid detection of melamine in milk, milk powder, and animal feed

Although high melamine (MEL) intake has been proven to cause serious health problems, MEL is sometimes illegally added to milk products and animal feed, arousing serious food safety concerns. A satisfactory method of detecting MEL in onsite or in-home testing is in urgent need of development. This work aimed to explore a rapid, convenient, and cost-effective method of identifying MEL in milk products or other food by colloidal selenium-based lateral flow immunoassay. Colloidal selenium was synthesized by L-ascorbic acid to reduce seleninic acid at room temperature. After conjugation with a monoclonal antibody anti-MEL, a test strip was successfully prepared. The detection limit of the test strip reached 150 μg/kg, 1,000 μg/kg, and 800 μg/kg in liquid milk, milk powder, and animal feed, respectively. No cross-reactions with homologues cyanuric acid, cyanurodiamide, or ammelide were found. Moreover, the MEL test strip can remain stable after storage for 1 year at room temperature. Our results demonstrate that the colloidal selenium MEL test strip can detect MEL in adulterated milk products or animal feed conveniently, rapidly, and sensitively. In contrast with a colloidal gold MEL test strip, the colloidal selenium MEL test strip was easy to prepare and more cost-efficient.

Development of a United Kingdom National External Quality Assessment Scheme (UK NEQAS) for HIV point of care testing

The use of HIV point of care tests (POCTs) is increasing rapidly in both laboratory and other settings. These tests are often performed by non-laboratory trained staff. At the present time there are no external quality assessment (EQA) providers in the UK offering proficiency testing schemes for HIV point of care testing. The aim of this study is to develop such an EQA scheme. Firstly, a selection of the most widely used POCTs was selected and their performance assessed using existing HIV-positive serology EQA specimens. All assays produced the correct results however intensity of results observed for the same specimen differed greatly between POCT devices. In addition the effect of various sub-groups of HIV-1 serum samples on the HIV POCT assays was investigated and no difference between the results on the POCTs was observed. Ultimately four serum specimens, two HIV-1 and one HIV-2 positive, one HIV negative, were chosen and sent to NHS laboratories and sexual health clinics for testing as part of a pilot EQA scheme for HIV POCT. Results were excellent with 97% of participants reporting correct results (n= 20). The study highlighted a lack of awareness of EQA particularly in non-laboratory settings, although recommendations (ISO 22870:2006) are in place for the users of such devices. In conclusion, the need for EQA for providers of point of care testing is an integral part of ensuring reliability of results and quality of care for the patient.

Four new HIV-1 group N isolates from Cameroon: Prevalence continues to be low

Analysis of 3555 HIV-seropositive specimens, collected in Cameroon from 2002 to 2006, led to the identification of four HIV-1 group N infections based on differential seroreactivity to HIV env-derived peptides and proteins and confirmation by nucleic acid amplification. Group N prevalence continues to be low accounting for only 0.1% of HIV infections in Cameroon. Near full-length genomic sequences were obtained from viral RNA or proviral DNA by PCR amplification of overlapping fragments for three isolates, 06CM-U14296, 06CM-U14842, and 02CM-SJGddd. Two genome segments, partial pol and env-nef, were obtained from viral RNA for the fourth isolate, 02CM-TIM0217. With the four group N isolates identified in this study and group N sequences previously reported, eight near full-length and five partial genome sequences are now available. Despite genetic divergence from HIV-1 group M and O, all of the group N infections evaluated by five commercial HIV immunoassays were detected.

HIV type 2 intergroup recombinant identified in Cameroon

A unique HIV-2 intergroup recombinant strain was identified in Cameroon. The virus, CM-03-510-03, was amplified from blood collected from a 47-year-old female patient in Douala, Cameroon in 2003 who was seroreactive for HIV-2. A near full-length genome 9089 nucleotides in length was amplified from proviral DNA. The genome for CM-03-510-03 is composed of segments of HIV-2 groups A and B with four recombination break-points and has open reading frames for all the structural and regulatory genes. A comparison of CM-03-510-03 to the only previously reported HIV-2 intergroup recombinant shows that the two strains share one recombination breakpoint but are otherwise distinct from each other. Similar to HIV-1, HIV-2 intergroup recombination is an indication that coinfection with more than one strain has occurred in individuals and is a mechanism that increases strain genetic diversity.

Identification of HIV type 1 group N infections in a husband and wife in Cameroon: viral genome sequences provide evidence for horizontal transmission

HIV-1 is classified into three groups, M (major), N (non-M non-O), and O (outlier); each group arose from a separate transmission of SIVcpz into humans. HIV-1 group N was recently discovered and infections with this virus are rare with only eight documented cases. All group N infections have been found in Cameroon and there is no evidence of direct linkage between the infected patients. We report here the identification of HIV-1 group N infections in a husband and wife. The group N infection in the husband, 1131-03, was identified first based on seroreactivity in peptide EIAs and confirmed by PCR amplification of group N viral sequences. Subsequently the wife, 1015-04, was evaluated and confirmed to also be infected with a group N virus. Near full-length viral genomes were amplified and sequenced from each patient's specimen. The low level of diversity between the two viral sequences provides evidence of horizontal transmission of group N from one spouse to the other. Patient 1131-03 was receiving antiviral therapy consisting of reverse transcriptase inhibitors; the treatment appears effective for suppression of group N viral replication based on apparently low viral load in plasma specimens collected from the patient and the absence of drug resistance mutations in RT sequences amplified from 1131-03. This report brings to 10 the number of group N infections identified and to 5 the number of group N genomes sequenced. Although group N infections continue to be rare, group N is a pathogenic virus and its prevalence needs to be monitored.

A 10-minute, US Food and Drug Administration-approved HIV test

It is now an established fact that rapid HIV tests have important applications in a number of testing situations. Currently, four rapid HIV assays have been approved by the US Food and Drug Administration, including the one discussed in this review. A rapid, lateral flow HIV assay was evaluated at the University of Maryland, USA, one of several sites involved in the clinical evaluation. Samples used in the evaluation totaled 9000 and consisted of serum, plasma and venous whole-blood sets of samples from 3000 study subjects that included population groups considered to be at high risk for HIV infection (n=1000), from HIV-positive individuals (n=1000), and from population groups considered at low risk for HIV infection (n=1000). US Food and Drug Administration-licensed screening and confirmatory assays were used as reference tests. The rapid assay exhibited a sensitivity of 100% across all three sample media and exhibited a specificity of 99.8% using whole blood and plasma and 99.7% using serum. This rapid assay is an excellent addition to the existing US Food and Drug Administration-approved rapid HIV tests, and provides versatility by allowing the testing of venipuncture and fingerstick whole-blood samples in addition to serum and plasma.

HIV infections in northwestern Cameroon: identification of HIV type 1 group O and dual HIV type 1 group M and group O infections

HIV-1 strain diversity was examined in a study population that consisted of hospital and clinic patients from seven cities and villages located in the northwestern regions of Cameroon. Specimens were screened using a serological algorithm designed to identify HIV-1 group M, N, and O, and SIVcpz-like infections followed by RT-PCR amplification to characterize the infecting virus. The results show that the HIV epidemic in northwest Cameroon is dominated by HIV-1 group M CRF02_AG infections (57%). Additional group M subtypes present include A, D, F2, G, and CRF01_AE. Based on discordant subtype classification between gag and env sequences, a high percentage (23%) of viral strains appear to be unique intersubtype recombinants with the majority (88%) involving recombination with CRF02_AG. Group O prevalence is low accounting for only 0.4% of HIV infections. However, group O strain diversity is high; isolates from clades I, IV, and V, as well as unclassified and recombinant strains, were found. Three dual infections by HIV-1 group M and group O were identified and characterized. In two specimens, both group M and O sequences were amplified in gag, pol, and env suggesting the presence of both viruses. Analysis of the third specimen shows the presence of a group O virus and an intergroup M/O recombinant virus. Finally, no infections due to HIV-1 group N or SIVcpz-like strains were found in the study population.

Whole-blood agglutination assay for on-site detection of human immunodeficiency virus infection

Simple and rapid diagnostic tests are needed to curtail human immunodeficiency virus (HIV) infection, especially in the developing and underdeveloped nations of the world. The visible-agglutination assay for the detection of HIV with the naked eye (NEVA HIV, which represents naked eye visible-agglutination assay for HIV) is a hemagglutination-based test for the detection of antibodies to HIV in whole blood. The NEVA HIV reagent is a cocktail of highly stable recombinant bifunctional antibody fusion proteins with HIV antigens which can be produced in large quantities with a high degree of purity. The test procedure involves mixing of one drop of the NEVA HIV reagent with one drop of blood sample on a glass slide. The presence of anti-HIV antibodies in the blood sample leads to clumping of erythrocytes (agglutination) that can be seen with the naked eye. Evaluation with commercially available panels of sera and clinical samples has shown that the performance of NEVA HIV is comparable to those of U.S. and European Food and Drug Administration-approved rapid as well as enzyme-linked immunosorbent assay kits. The test detects antibodies to both HIV type 1 (HIV-1) and HIV-2 in a single spot and gives results in less than 5 min. The test was developed by keeping in mind the practical constraints of testing in less developed countries and thus is completely instrument-free, requiring no infrastructure or even electricity. Because the test is extremely rapid, requires no sample preparation, and is simple enough to be performed by a semiskilled technician in any remote area, NEVA HIV is a test for the hard-to-reach populations of the world.

Evaluation of HIV type 1 group O isolates: identification of five phylogenetic clusters

HIV-1 group O strains have a level of genetic diversity similar to that of strains in group M; however, group O has not been readily classified into genetic subtypes. Phylogenetic classification of group O has been hindered by the limited sequence information available. To facilitate phylogenetic analysis, we sequenced the gag p24 (693 nt), pol p32 (864 nt), and env gp160 (approximately 2700 nt) genes from 39 group O-infected specimens. These specimens include 32 plasma samples collected in Cameroon between 1996 and 1999, 2 specimens collected in the United States, and 5 infections previously isolated in Equatorial Guinea. Phylogenetic analysis of HIV-1 group O sequences resulted in the identification of five clusters that are maintained across gag, pol, and env, generally supported by high bootstrap values, and approximately equidistant from each other. In addition to the group O clusters, several isolates branch independently and are equidistant from the other group O isolates. Cluster I comprises greater than 50% of the group O isolates and is a diverse set of isolates that is subdivided into subclusters. The average intra-, sub-, and intercluster distances for group O are similar to the corresponding distances for group M subtypes. The five group O clusters have characteristics similar to those of group M subtypes. Thus the data presented may form the basis for classification of group O into subtypes. However, full-length genomes representing each group O cluster will be required to formalize a group O subtype classification.

Suitability of a rapid immunochromatographic test for detection of antibodies to human immunodeficiency virus in Ghana, West Africa

In West African countries such as Ghana, efficient human immunodeficiency virus (HIV) testing is a priority in the fight against AIDS. A new immunochromatographic rapid test, Determine HIV-1/2 (Abbott Diagnostics, North Chicago, Ill.), that detects antibodies against HIV type 1 (HIV-1) and/or HIV-2 was evaluated using Ghanaian blood samples. Two hundred four serum and/or plasma specimens were tested. HIV screening was done by a particle agglutination test and confirmed by a Western blot (WB) test as the "gold standard." The results revealed 125 HIV-seropositive AIDS patients, 75 HIV-seronegative healthy individuals, and 4 individuals for whom the HIV-1 result was indeterminate. The results obtained by the Determine HIV-1/2 assay and Diagnostic HIV SPOT (Genelabs), which is currently widely used in many districts in Ghana, were compared with those of the WB test, excluding the four HIV-1-indeterminate samples. The sensitivity of the Determine HIV-1/2 assay was 100%, compared with 98.0% for the HIV SPOT assay. The specificity was 100% for both tests. Determine HIV-1/2 is a single-step assay and was found to be rapid and easy to perform without any special equipment. It was highly sensitive and specific. The kit can be applied without electricity and water supplies, making it suitable for the detection of HIV antibodies especially in the rural areas of Ghana, West Africa.

Assessment of the performance of a rapid, lateral flow assay for the detection of antibodies to HIV

Rapid HIV assays have recently been shown to have important applications for various testing situations, including early identification of infected individuals, to allow intervention strategies in a clinically relevant time frame. A rapid, lateral flow, HIV-1/2/O assay was evaluated using 2,000 serum or plasma samples from various risk groups and geographic locations, including HIV-1 and HIV-2 positive sera from five countries. Two U.S. Food and Drug Administration (FDA)-licensed screening assays and a FDA-licensed confirmatory assay were used as reference tests. The rapid assay exhibited a near-perfect sensitivity (99.2%) and an excellent specificity (99.9%). Moreover, its analytical sensitivity was found to be better than most FDA-licensed enzyme-linked immunosorbent assays (ELISAs), detecting infection at the same time as the most sensitive ELISA in two of five seroconversion panels, and at the same time or earlier than four of five ELISAs in all five panels. We conclude that this rapid assay is a suitable test for the detection of HIV infection that could be particularly useful in developing countries where facilities may not support the use of instrumentation.