Vero cells were cultured in Dulbecco's modified Eagle's medium (DMEM)-5 % fetal calf serum (FCS)-4 mM glutamine. Before seeding the cells, a sterilized (ethanol, UV) coverslip (18×18 mm 2 ) was placed in each well. One day before inoculation, 6-well plates were seeded with 4×10 5 Vero cells/well. Biological fluid samples were diluted (1: 15.625 for serum, 1:10 for all other fluids) in dilution medium (DMEM-1 % antibiotics) and 700 μl of each fluid sample was added to Vero cells for 2 h of inoculation (37°C, 5 % CO 2 ). Inoculum was then removed and 2 ml of survival medium (DMEM-2 % FCS-4 mM of glutamine-1 % antibiotics) supplemented with 1 % (v/v) low-melting agarose was added. The plates were incubated (37°C, 5 % CO 2 ) for 6 days. As a positive control, Vero cells were inoculated with100 CCID 50 of MV1-F4 viral suspension (as described above) and diluted in 700 μl dilution medium. As a negative control, Vero cells were inoculated with 700 μl dilution medium.