Detection of HIV-1 p24 at attomole level by ultrasensitive ELISA with Thio-NAD cycling

Akira Nakatsuma, Mugiho Kaneda, Hiromi Kodama, Mika Morikawa, Satoshi Watabe, Kazunari Nakaishi, Masakane Yamashita, Teruki Yoshimura, Toshiaki Miura, Masaki Ninomiya, Etsuro Ito

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22 Citations (Scopus)


To reduce the window period between HIV-1 infection and the ability to diagnose it, a fourthgeneration immunoassay including the detection of HIV-1 p24 antigen has been developed. However, because the commercially available systems for this assay use special, high-cost instruments to measure, for example, chemiluminescence, it is performed only by diagnostics companies and hub hospitals. To overcome this limitation, we applied an ultrasensitive ELISA coupled with a thio-NAD cycling, which is based on a usual enzyme immunoassay without special instruments, to detect HIV-1 p24. The p24 detection limit by our ultrasensitive ELISA was 0.0065 IU/assay (i.e., ca. 10-18 moles/assay). Because HIV-1 p24 antigen is thought to be present in the virion in much greater numbers than viral RNA copies, the value of 10-18 moles of the p24/assay corresponds to ca. 103 copies of the HIV-1 RNA/assay. That is, our ultrasensitive ELISA is chasing the detection limit (102 copies/assay) obtained by PCR-based nucleic acid testing (NAT) with a margin of only one different order. Further, the detection limit by our ultrasensitive ELISA is less than that mandated for a CE-marked HIV antigen/antibody assay. An additional recovery test using blood supported the reliability of our ultrasensitive ELISA.

Original languageEnglish
Article numbere0131319
JournalPloS one
Issue number6
Publication statusPublished - 2015 Jun 22
Externally publishedYes

ASJC Scopus subject areas

  • General


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