The reactions are performed in a thermocycler with heated lid (105°C) in 0.2 ml thin-walled PCR tubes. The specific MLPA reagents can be obtained from MRC-Holland. The various probes and oligonucleotides used in the honey bee virus MLPA are given in Table 6. It is recommended to use the wildtype MuMLV Reverse Transcriptase from Promega (M1701). The right probe oligos (RPO) are phosphorylated and should be synthesized as ‘ultramer’ grade.