Virus leakage through natural membrane condoms

The authors determined virus leakage from condoms made from processed sheep caecum using two viral probes simultaneously. They poured a mixture of two viruses, the bacteriophage, phi X174 (4 X 10(7) pfu/ml), and the human pathogen, herpes simplex virus (about 1 X 10(6) pfu/ml), in a buffered solution into condoms, which were suspended into beakers also containing buffered solution. The authors then assayed aliquots from the beakers to measure the extent of virus leakage from the condoms. With one brand of condom, 10 out of 24 samples leaked small amounts of phi X174; with the other brand of condom, 13 out of 24 samples gave similar leakage. The extent of leakage varied over two orders of magnitude from condom to condom within each brand. Of the 23 condoms that leaked the smaller virus, phi X174 (27 nm in diameter), only two also leaked the larger herpesvirus (120-150 nm in diameter). These data demonstrate that (1) large and small viruses can leak from natural membrane condoms; (2) there is considerable variation from condom to condom in allowing leakage of the viruses; and (3) leakage of a small virus does not necessarily indicate that a larger virus will leak from that particular condom. The authors explain some inconsistencies in the published literature.