Impact of nucleic acid testing relative to antigen/antibody combination immunoassay on the detection of acute HIV infection

Mark S. De Souza*, Nittaya Phanuphak, Suteeraporn Pinyakorn, Rapee Trichavaroj, Supanit Pattanachaiwit, Nitiya Chomchey, James L. Fletcher, Eugene D. Kroon, Nelson L. Michael, Praphan Phanuphak, Jerome H. Kim, Jintanat Ananworanich, Nipat Teeratakulpisarn, Donn Colby, Duanghathai Sutthichom, Somprartthana Rattanamanee, Peeriya Mangyu, Sasiwimol Ubolyam, Pacharin Eamyoung, Suwanna PuttamaswinSomporn Tipsuk, Putthachard Sangtawan, Viseth Ngauy, Robert O'Connell, Siriwat Akapirat, Nantana Tantibul, Hathairat Savadsuk, Vatcharain Assawadarachai, Merlin Robb, Sodsai Tovanabutra

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


Objective: To assess the addition of HIV nucleic acid testing (NAT) to fourth-generation (4thG) HIV antigen/antibody combination immunoassay in improving detection of acute HIV infection (AHI). Methods: Participants attending a major voluntary counseling and testing site in Thailand were screened for AHI using 4thG HIV antigen/antibody immunoassay and sequential less sensitive HIV antibody immunoassay. Samples nonreactive by 4thG antigen/antibody immunoassay were further screened using pooled NAT to identify additional AHI. HIV infection status was verified following enrollment into an AHI study with follow-up visits and additional diagnostic tests. Results: Among 74 334 clients screened for HIV infection, HIV prevalence was 10.9% and the overall incidence of AHI (N = 112) was 2.2 per 100 person-years. The inclusion of pooled NAT in the testing algorithm increased the number of acutely infected patients detected, from 81 to 112 (38%), relative to 4thG HIV antigen/antibody immunoassay. Follow-up testing within 5 days of screening marginally improved the 4thG immunoassay detection rate (26%). The median CD4 + T-cell count at the enrollment visit was 353 cells/μl and HIV plasma viral load was 598 289 copies/ml. Conclusion: The incorporation of pooled NAT into the HIV testing algorithm in high-risk populations may be beneficial in the long term. The addition of pooled NAT testing resulted in an increase in screening costs of 22% to identify AHI: from $8.33 per screened patient to $10.16. Risk factors of the testing population should be considered prior to NAT implementation given the additional testing complexity and costs.

Original languageEnglish
Pages (from-to)793-800
Number of pages8
Issue number7
StatePublished - 24 Apr 2015
Externally publishedYes


  • Bangkok
  • Fiebig
  • HIV antigen/antibody combination assay
  • acute HIV infection
  • pooled nucleic acid testing


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