Could the new HIV combined p24 antigen and antibody assays replace p24 antigen specific assays?

Performance of the Liaison XL Murex HIV Ab/Ag Test on Clinical Samples Representing Current Epidemic HIV Variants

“…This ability to distinguish between signals gives a quick indication of the date of infection before the completion of confirmatory tests (such as Western blotting or immunoblotting) and enables primary infections to be identified more rapidly and easily. There is currently no consensus regarding the possibility of replacing the HIV p24 test with this type of combined test, the lack of a confirmation assay based on neutralization being problematic if the findings are inconclusive (8).…”

“…Fourth-generation tests, which detect antibodies against both the virus and the viral antigen p24, are now recommended in France and elsewhere (5,6) due to their great potential for detecting early infections. Indeed, their utilization reduces the diagnostic window by 1 to 3 weeks, depending on the generation of the test in the comparison (7)(8)(9). However, any diagnostic test also has to be able to detect all circulating HIV variants.…”

HIV-1 Diversity and Its Implications in Diagnosis, Transmission, Disease Progression, and Antiretroviral Therapy

“…These assays provide an advantage for detection of infection during the window period prior to seroconversion since the diagnostic window may be reduced by an average of 5 days relative to an IgM-sensitive EIA (Fiebig et al, 2003;Weber et al, 1998). However, some fourth-generation assays showed low sensitivity in the detection of p24 antigen from some non-subtype B HIV-1 strains (A, C, F, H, CRF01_AE, O) (Kwon et al, 2006;Ly et al, 2007;Ly et al, 2004;Ly et al, 2001;Weber, 2002). This low sensitivity in antigen detection may be attributed to differences in viral epitopes of the different HIV genetic forms which may not be recognized by the monoclonal antibody used in the assay (Plantier et al, 2009a).…”

“…Key epitope(s) targeted by these assays might be modified or eliminated by the occurrence of natural polymorphisms within the IDR region associated with the genetic variation of HIV-1, ultimately leading to reduced sensitivity or lack of antibody detection (Brennan et al, 2006;Gaudy et al, 2004). A few cases of false-negative results involving, for example, subtypes B, C, and F, and resulting from major mutations of the IDR epitope have been described (Aghokeng et al, 2009;Gaudy et al, 2004;Ly et al, 2007;Ly et al, 2004;Ly et al, 2001;Zouhair et al, 2006). Earlier analysis of specimens from patients infected with group O viruses revealed that some commercial immunoassays failed to detect group O infections (Eberle et al, 1997;Loussert-Ajaka et al, 1994;Schable et al, 1994;Simon et al, 1994).…”

Saliva as a Diagnostic Medium

“…Given that no vaccine has been developed against HIV infection to date, detection of antiviral antibodies remains standard for identifying infected people and determining the risk of transmitting the infection. Current studies are therefore focused primarily on detecting antibodies and the p24 gene 51 . Direct detection and identification of the presence of the virus in saliva using the PCR method is gradually becoming the standard method.…”