Despite significant advancement in vaccine and virus research, influenza continues to be a major public health concern. Each year in the United States of America, influenza viruses are responsible for seasonal epidemics resulting in over 200,000 hospitalizations and 30,000–50,000 deaths. Accurate and early diagnosis of influenza viral infections are critical for rapid initiation of antiviral therapy to reduce influenza related morbidity and mortality both during seasonal epidemics and pandemics. Several different approaches are currently available for diagnosis of influenza infections in humans. These include viral isolation in cell culture, immunofluorescence assays, nucleic acid amplification tests, immunochromatography-based rapid diagnostic tests, etc. Newer diagnostic approaches are being developed to overcome the limitations associated with some of the conventional detection methods. This review discusses diagnostic approaches currently available for detection of influenza viruses in humans.

We developed a europium nanoparticle-based immunoassay (ENIA) for the sensitive detection of anthrax protective antigen (PA). The ENIA exhibited a linear dose-dependent pattern within the detection range of 0.01 to 100 ng/ml and was approximately 100-fold more sensitive than enzyme-linked immunosorbent assay (ELISA). False-positive results were not observed with serum samples from healthy adults, mouse plasma without PA, or plasma samples collected from mice injected with anthrax lethal factor or edema factor alone. For the detection of plasma samples spiked with PA, the detection sensitivities for ENIA and ELISA were 100% (11/11 samples) and 36.4% (4/11 samples), respectively. The assay exhibited a linear but qualitative correlation between the PA injected and the PA detected in murine blood ( r = 0.97731; P < 0.0001). Anthrax PA was also detected in the circulation of mice infected with spores from a toxigenic Sterne-like strain of Bacillus anthracis , but only in the later stages of infection. These results indicate that the universal labeling technology based on europium nanoparticles and its application may provide a rapid and sensitive testing platform for clinical diagnosis and laboratory research.

The assays used to detect XMRV in patients with chronic fatigue syndrome are unreliable.

Nanotechnology-based techniques are being widely evaluated in medical testing and could provide a new generation of diagnostic assays due to their high degrees of sensitivity, high specificity, multiplexing capabilities, and ability to operate without enzymes. In this article, we have modified a nanoparticle-based biobarcode amplification (BCA) assay for early and sensitive detection of HIV-1 capsid (p24) antigen by using antip24 antibody-coated microplates to capture viral antigen (p24) and streptavidin-coated nanoparticle-based biobarcode DNAs for signal amplification, followed by detection using a chip-based scanometric method. The modified BCA assay exhibited a linear dose-dependent pattern within the detection range of 0.1 to 500 pg/ml and was approximately 150-fold more sensitive than conventional enzyme-linked immunosorbent assay (ELISA). No false positive results were observed in 30 HIV-1-negative samples, while all 45 HIV-1 RNA positive samples were found HIV-1 p24 antigen positive by the BCA assay. In addition, the BCA assay detected HIV-1 infection 3 days earlier than ELISA in seroconversion samples. Preliminary evaluation based on testing a small number of samples indicates that the HIV-1 p24 antigen BCA may provide a new tool for sensitive and early detection of HIV-1 p24 antigen in settings where HIV-1 RNA testing is currently not routinely performed.