[Could saliva be used to detect HIV seroconversion?].

INTRODUCTION

Blood is generally used for detection of antibodies associated with infections. However, removal of blood samples can be problematic and is painful for the patient. It requires suitable equipment and skilled staff, both of which may be expensive. Some patients refuse to allow removal of blood samples because they find it painful and traumatic. Removal of blood samples from children, newborns, immunocompromised or overweight subjects is often particularly difficult. In addition, some religions forbid the taking of blood samples. Thus, it is necessary to develop alternative, simple, painless methods of sampling body fluids that give results as accurate as those obtained with blood samples. Saliva has been suggested as a possible alternative. Epidemiological studies and other reports have shown that saliva may be of value for the detection of HIV antibodies.

AIM

To evaluate the potential of saliva for detection of antibodies and seroconversion.

MATERIALS AND METHODS

Section I: Saliva and serum from 1,023 subjects, including 150 AIDS patients, 251 TB patients of known HIV status and 622 subjects from at-risk groups were tested. Sera from subjects with unknown HIV status were systematically tested by Abbott recombinant HIV1/HIV2 EIA. Section II: Saliva and sera were obtained from a population at risk of HIV infection. Two hundred and fifty consenting adults were found to be HIV-negative. Saliva was collected from each subject once per week and tested the same day with the Abbott test pack and Wellcozyme GACELISA. A spot of blood was also collected, dried and tested using the Wellcozyme GACELISA protocol. Whenever a positive result was obtained for any test, a blood sample was taken the same day or as soon as possible, for Western, blot analysis. Saliva was collected with an OMNISAL device (SDS, Vancouver, USA) placed under the tongue. The indicator turned blue when enough fluid had been collected. The device was then removed and the saliva placed in a tube with stabilized product. It was then transferred to a casting tube with a filter.

RESULTS

Section I: Saliva from 96 of 150 AIDS patients (64%) tested positive. Serum from these patients also tested positive for HIV. Thirty-two subjects of the 622 from at-risk groups tested positive for HIV in the Abbott recombinant HIV1/HIV2 EIA with saliva (5.14%). Serum from these subjects also tested positive for HIV in Western blot. However, saliva EIA gave 5 false negative results for patients who tested positive in rapid tests and Western blot. We optimized the procedure and obtained 98.69% sensitivity and 100% specificity. Section II: One individual tested positive in saliva and dried blood spot tests in the fourth week of the study. Western blot using serum samples obtained on the next and following days showed a progressive increase in the intensity of the bands, beginning with P24 and GP160 (Fig. 2).

CONCLUSION

This study shows that testing saliva is effective for determining HIV status early in seroconversion.