Multi-center European evaluation of HIV testing on serum and saliva samples

Area of Science:

• Immunology
• Infectious Diseases
• Public Health

Background:

• HIV antibody testing is crucial for diagnosis and surveillance.
• Saliva offers a non-invasive alternative to blood for sample collection.
• Evaluating the accuracy of alternative sample types is essential for expanding testing accessibility.

Purpose of the Study:

• To assess the reliability of HIV antibody detection in saliva samples.
• To compare saliva-based HIV testing performance against traditional serum-based methods.
• To determine the suitability of saliva testing for epidemiological surveillance versus clinical diagnosis.

Main Methods:

• Matched serum and saliva samples were collected from 344 HIV-negative and 125 HIV-positive individuals across Europe.
• Samples were tested using Enzyme Immunoassays (EIA) with modifications for saliva, followed by Western blot confirmation for reactive or doubtful results.
• Two different EIA kits (Recombinant HIV1 EIA Cambridge Bioscience and Abbott HIV 1&2 1A80) were utilized.

Main Results:

• Serum analysis demonstrated high sensitivity (99.2%-100%) and specificity (100%) for both EIA tests.
• Saliva testing showed variable results, with some samples from seropositive individuals testing negative or indeterminate by EIA and Western blot.
• One HIV2-infected individual's saliva sample tested negative by both EIA methods, despite meeting Western blot criteria for positivity.

Conclusions:

• The reliability of HIV antibody testing in saliva depends on the sensitivity of the immunoassay and the interpretation criteria for confirmatory tests.
• While saliva testing presents advantages for epidemiological studies, its current limitations make it unsuitable for definitive HIV diagnosis.
• Further refinement of saliva-based HIV testing protocols is needed before clinical diagnostic recommendations can be considered.