Detection of rubella immunoglobulin M from dried venous blood spots using a commercial enzyme immunoassay

Development of a Rapid Immuno-Based Screening Assay for the Detection of Adenovirus in Eye Infections

Despite progress in fighting infectious diseases, human pathogenesis and death caused by infectious diseases remain relatively high worldwide exceeding that of cancer and cardiovascular diseases. Human adenovirus (HAdV) infects cells of the upper respiratory tract causing flu-like symptoms that are accompanied by pain and inflammation. Diagnosis of HAdV is commonly achieved by conventional methods such as viral cultures, immunoassays, and polymerase chain reaction (PCR) techniques. However, there are a variety of problems with conventional methods including slow isolation and propagation, inhibition by neutralizing antibodies, low sensitivity of immunoassays, and the diversity of HAdV strains for the PCR technique. Herein, we report the development and evaluation of a novel, simple, and reliable nanobased immunosensing technique for the rapid detection of human adenoviruses (HAdVs) that cause eye infections. This rapid and low-cost assay can be used for screening and quantitative tests with a detection limit of 10² pfu/mL in less than 2 min. The sensing platform is based on a sandwich assay that can detect HAdVs visually by a color change. Sensor specificity was demonstrated using other common viral antigens, including Flu A, Flu B, coronavirus (COV), and Middle East respiratory syndrome coronavirus (MERS COV). This cotton-based testing device potentially exhibits many of the desired characteristics of a suitable point-of-care and portable test, which can be carried out by nurses or clinicians especially for low-resource settings.

Detection of infections with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus by analyses of dried blood spots--performance characteristics of the ARCHITECT system and two commercial assays for nucleic acid amplification

BACKGROUND

Nowadays, dried blood spots (DBS) are primarily used to obtain diagnostic access to risk collectives such as intravenous drug users, who are prone to infections with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Before DBS analyses can be used in this diagnostic context, however, a comprehensive evaluation of its performance characteristics must be conducted. To the best of our knowledge, the current study presents for the first time such essential data for the Abbott ARCHITECT system, which is currently the worldwide leading platform in this field of infection diagnostics.

METHODS

The investigation comprised 1,762 paired serum/DBS samples and a total of 3,524 determinations with the Abbott ARCHITECT HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24-antigen/anti-HIV 1/2 assays as well as with the artus HBV LC PCR and VERSANT HCV RNA qualitative (TMA) tests.

RESULTS

In the context of DBS testing, a specificity of 100% was recorded for the seven serological and molecular biological assays. The analytical sensitivity of HBsAg, anti-HBc, anti-HBs, anti-HCV, HIV-1-p24-antigen/anti-HIV 1/2, HBV DNA, and HCV RNA detections in DBS eluates was 98.6%, 97.1%, 97.5%, 97.8%, 100%, 93%, and 100%, respectively.

DISCUSSION/CONCLUSIONS

The results obtained indicate that it is today possible to reliably detect HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24 antigen/anti-HIV 1/2 with state-of-the-art analytical systems such as the Abbott ARCHITECT in DBS eluates even when a comparatively high elution volume of 1,000 μl is used. They also provide evidence for the inherent analytical limits of DBS testing, which primarily concern the anti-HBc/anti-HBs system for individuals with HIV infections and nucleic acid tests with relatively low analytical sensitivity.

Expansion of the global measles and rubella laboratory network 2005-09

Enhancing measles surveillance with integration of epidemiologic and laboratory information is one of the key strategies for accelerated measles control and elimination. The World Health Organization (WHO) Global Measles and Rubella Laboratory Network (LabNet) has been developed since 2000 to currently include 690 laboratories serving 183 countries. The LabNet testing strategy follows well-validated, standardized procedures for confirming suspected cases and for monitoring measles and rubella virus transmission patterns. The strength of the LabNet is a strong quality assurance program that monitors the performance of all laboratories through annual proficiency testing and continuous assessment. In the 5-year period 2005-2009, the results of >1 million measles immunoglobulin M (IgM) tests have been reported by the LabNet and, in addition, sequence information on >7000 measles and 600 rubella viruses has been shared. Progress with the development of the LabNet during 2005-2009 is discussed.

The use of dried blood spots for assessing antibody response to hepatitis A virus after natural infection and vaccination

During recent years, vaccination against hepatitis A has been implemented in several countries. It is expected that the increase in mass vaccination against hepatitis A will eventually result in a decreased prevalence of anti-HAV antibodies in the general population. For this reason, a suitable clinical sample for diagnosis of hepatitis A must be sufficiently sensitive to enable detection of lower antibodies titers. In this study, the feasibility of using dried blood spots (DBS) was assessed for the detection of anti-HAV antibodies after a natural infection and vaccination. Seventy-four DBS and paired plasma samples were obtained from a group of college students for a cross-sectional hepatitis A seroepidemiological study. Forty-six students seronegative for anti-HAV were selected randomly and immunized with an inactivated hepatitis A vaccine using an 0-6 month schedule. Seroconversion was monitored in paired plasma and DBS samples 6 months after the first dose followed by a period of 8 and 24 months after the second dose. A strong correlation between OD/CO rates of paired plasma and DBS samples for the detection of anti-HAV was observed. The sensitivity and specificity of the DBS compared with plasma for the detection of anti-HAV antibodies after natural infection was 100%. The sensitivity of DBS in samples collected 24 months after the second dose of hepatitis A vaccine was 95.4%. The results showed that DBS samples can be used for the detection of anti-HAV antibodies both after natural infection or vaccination.

Use of dried serum spots for serological and molecular detection of hepatitis a virus

We assessed the feasibility of using dried serum spots (DSS) for the serological and molecular diagnosis of hepatitis A virus (HAV) infection. Sixty-eight sera spotted onto filter papers (Whatman International Ltd., United Kingdom) were used for detection of total anti-HAV antibodies, and 64 sera were used for detection of immunoglobulin M antibody to HAV. DSS were stored at 4 degrees C, room temperature, and 37 degrees C for 1, 2, and 4 weeks. Sensitivity and specificity of the serological assays were 100% regardless of temperature and storage duration. To assess the stability of HAV RNA, we performed qualitative and quantitative reverse transcription-PCRs (RT-PCRs) with human plasma spiked with serial dilutions of cultured HAV spotted on Flinders Technology Associates filter paper cards (Whatman International Ltd.). Filter papers were stored at room temperature and processed for RT-PCR assays. No reduction of viral load was observed after 5, 15, and 30 days of storage. The approximately 10-fold reduction of sensitivity from DSS was attributable to a smaller sample input in DSS samples. This method was further evaluated using 35 frozen sera. HAV RNA amplification showed 100% specificity and 92.3% sensitivity, and sequence analysis from DSS and sera provided identical results. HAV RNA can be accurately recovered from DSS for molecular epidemiology purposes, and we confirm the reliability of blotted samples in the serological diagnosis of HAV infection. The DSS method facilitates storage and shipment of samples from routine laboratories to reference centers for further investigations and large epidemiological studies.

Confirmation of rubella within 4 days of rash onset: comparison of rubella virus RNA detection in oral fluid with immunoglobulin M detection in serum or oral fluid

Rubella virus infection is typically diagnosed by the identification of rubella virus-specific immunoglobulin M (IgM) antibodies in serum, but approximately 50% of serum samples from rubella cases collected on the day of rash onset are negative for rubella virus-specific IgM. The ability to detect IgM in sera and oral fluids was compared with the ability to detect rubella virus RNA in oral fluids by reverse transcription-PCR (RT-PCR) by using paired samples taken within the first 4 days after rash onset from suspected rubella cases during an outbreak in Perú. Sera were tested for IgM by both indirect and capture enzyme immunoassays (EIAs), and oral fluids were tested for IgM by a capture EIA. Tests for IgM in serum were more sensitive for the confirmation of rubella than the test for IgM in oral fluid during the 4 days after rash onset. RT-PCR confirmed more suspected cases than serum IgM tests on days 1 and 2 after rash onset. The methods confirmed approximately the same number of cases on days 3 and 4 after rash onset. However, a few cases were detected by serum IgM tests but not by RT-PCR even on the day of rash onset. Nine RT-PCR-positive oral fluid specimens were shown to contain rubella virus sequences of genotype 1C. In summary, RT-PCR testing of oral fluid confirmed more rubella cases than IgM testing of either serum or oral fluid samples collected in the first 2 days after rash onset; the maximum number of confirmations of rubella cases was obtained by combining RT-PCR and serology testing.

Dry cotton or flocked respiratory swabs as a simple collection technique for the molecular detection of respiratory viruses using real-time NASBA

This paper describes the molecular detection of influenza A, influenza B, respiratory syncytial virus and human metapneumovirus using real-time nucleic acid sequence based amplification (NASBA) from respiratory samples collected on simple dry cotton swabs, non-invasively and in the absence of transport medium. Viral RNA was detectable on dry cotton and flocked swabs for at least 2 weeks at room temperature and was readily extracted using magnetic silica extraction methods. Dry cotton respiratory swabs were matched with traditionally collected respiratory samples from the same patient, and results of traditional laboratory techniques and real-time NASBA were compared for all four viral targets. The results not only showed a significant increase in the detection rate of the viral targets over traditional laboratory methods of 46%, but also that dry swabs did not compromise their recovery. Over two subsequent winter seasons, 736 dry cotton respiratory swabs were collected from symptomatic patients and tested using real-time NASBA giving an overall detection rate for these respiratory virus targets of 38%. The simplicity of the method together with the increased detection rate observed in the study proves that transporting a dry respiratory swab to the laboratory for respiratory virus diagnosis using molecular methods is a suitable and robust alternative to traditional sample types.

Dried blood spots versus sera for detection of rubella virus-specific immunoglobulin M (IgM) and IgG in samples collected during a rubella outbreak in Peru

Most persons with rubella virus-specific immunoglobulin M (IgM)- or IgG-positive sera tested positive (98% [n = 178] and 99% [n = 221], respectively) using paired filter paper dried blood spot (DBS) samples, provided that DBS indeterminate results were called positive. For persons with IgM- or IgG-negative sera, 97% and 98%, respectively, were negative using DBS.

Reducing global disease burden of measles and rubella: Report of the WHO Steering Committee on research related to measles and rubella vaccines and vaccination, 2005

The WHO Steering Committee reviewed and evaluated the progress towards global control of measles and rubella and provided guidelines for future research activities concerning both diseases during its meeting in New Delhi, in April 2005. Global measles vaccination coverage increased from 71% in 1999 to 76% in 2004 and indigenous transmission was interrupted or kept at very low levels in many countries. However, Africa and Southeast Asia continue to experience endemic transmission and high mortality rates, despite a global mortality reduction of 39% between 1999 and 2003. On the basis of reports from countries with continued indigenous measles virus transmission, future control strategies as well as advantages and potential drawbacks of global measles eradication were discussed. Similarly the burden of rubella and congenital rubella syndrome (CRS) as well as the cost-effectiveness of rubella vaccination was assessed using different methods in several countries without vaccination programs. As measles and rubella viruses continue to circulate surveillance and control strategies need further optimization. RT-PCR was considered as an alternative method for laboratory diagnosis of CRS. The value of dried blood spots and oral fluid as alternative samples for measles and rubella IgG and IgM detection and genotype determination was evaluated. However further validation of these methods in different settings is required before their routine use can be recommended.

Comparison of available methods to elute serum from dried blood spot samples for measles serology

Six existing protocols for the extraction of serum from blood spots dried onto filter paper were compared. Assessment criteria included: detection of measles IgM and IgG by the Dade Behring Enzygnost immunoassays, volumes of recovered eluates, reproducibility, processing time and throughput, difficulty of protocol, equipment required, safety and estimated costs. Detection of measles IgM in eluates obtained by four of these protocols was as in serum, and significant differences were only observed in eluates from the two remaining protocols (p < 0.05). Significant differences were found between extraction protocols regarding measles-specific IgG detection when an IgG indeterminate DBS was analyzed (p < 0.05), but not when an IgG positive and negative DBS were studied. Sufficient eluate volumes were recovered for testing in the IgM Behring assay following all protocols but two. Sufficient eluate was recovered for testing in the IgG Behring assay following all six protocols. While all protocols were relatively easy to perform, only two protocols required less than 2h for completion. In general, compared protocols performed well on the extraction of antibodies from DBS for serology with differences being observed with eluate volume recovery, turn around time, required equipment and cost. An easy-to-implement protocol is proposed for the rapid extraction of serum for measles/rubella serology in outbreak situations for use in the World Health Organization Global Measles and Rubella Laboratory Network.