Development of multiple primer, HIV mini-pool NAT and its application in detecting acute infection of MSM

Abstract

Objective To establish a mini-pool nucleic acid testing (NAT) assay using multiplex RT-nested PCR for the detection of HIV RNA, and apply it in screening for acute HIV infection among MSM. Methods Frozen EDTA plasma samples collected between Oct. 2008 and Mar. 2009 from 3 HIV infectors during window-period, a total of 30 HIV chronically infected individuals and 97 healthy subjects were used to develop the NAT assay. Plasma samples from 10 cases were pooled into one tube and centrifuged at high speed for the collection of viruses. HIV RNA was extracted. Two pairs of primers were designed according to two conserved regions of HIV RNA ( HXB2 nt 5783-nt 6228 and nt 1235-nt 2012).Multiplex RT-PCR and nested PCR were performed. Individual NAT-reactive samples were confirmed by commercially available NAT assays. The sensitivity and performance efficacy were also evaluated. The assay was then applied to 1 005 plasma specimens from MSM with negative or uncertain HIV antibody test results.These were collected in the same period as the other samples. Results ( 1 ) Two fragments of HIV were amplified successfully with the low detection limit of 162 copies/ml plasma; (2) Results of the mini-pool HIV NAT validation with samples from 3 HIV infectors during window-period were consistent with the expected values; (3) All 30 plasma samples from MSM with positive HIV antibody, which were tested by multiplex RT nested PCR, were found to be HIV RNA positive; (4) One out of 1 005 plasma samples was found to be HIV RNA positive, for this case acute infection was followed-up and sero-conversion was found. Conclusion Mini-pool NAT has good sensitivity, and may be applied to screening HIV RNA among MSM during window-period. Key words: HIV infections; Homosexuality, male; HIV-1; Nucleic acid amplification techniques