Detection of antibodies to human immunodeficiency virus type 2 (HIV-2) in blood donor sera using United States assay methods for anti-HIV type 1

Existing problems in the testing for infectious diseases

Current methods for testing donated blood for presence of infectious viral agents in the USA differ from those used in other countries because of the USA Food and Drug Administration's (FDA) control which inhibits rapid introduction of testing methods or improvements. Delays in FDA approval may occur because of concerns about methodology or the state of knowledge about the disease it is intended to detect as well as due to variability between manufacturers. Despite strict FDA control, testing problems continue to occur in the USA. No approved method detects infectious agents during the "window period," and variations in detection, i.e., false positives and false negatives (even with confirmatory testing), continue to occur. The effect of physical and chemical changes (e.g., various anticoagulants) on samples has not been thoroughly evaluated. Test performance problems include lapses in sample identification, failure to use routine laboratory controls, improper calculation and reporting of results, improper acceptance of test runs and failure to properly detect and retest samples when carryover from very reactive samples occurs. For these reasons, transfusion-related disease transmission continues to occur. The current USA emphasis on good manufacturing practices should provide continuous improvements.

Comparison of indirect immunofluorescence and membrane fluorescence assays for the differentiation of antibodies to human immunodeficiency virus types 1 and 2

Serum samples from 20 human immunodeficiency virus type 1 (HIV-1)- and 30 HIV-2-infected and 7 dually infected individuals were reacted by using the indirect immunofluorescence assay (IFA) and membrane fluorescence assay in order to determine whether these methods were useful for typing HIV-1 and HIV-2 antibodies. Although 41 of 50 (82%) of the HIV-1- and HIV-2-positive specimens cross-reacted to some extent with the heterologous antigen in the IFA, the antigen with the higher titer correlated completely with the infecting type. The IFA could not distinguish single from dual infections, however. In contrast, only 4 of the 50 (8%) serum samples cross-reacted in the membrane fluorescence test. All seven of the specimens from patients with mixed infections reacted with both antigens. The membrane fluorescence test appears to be reliable for serodifferentiation of HIV-1 and HIV-2 infections and may be useful for laboratories with low-volume typing requirements.