RNA samples from day 4 were also probed for genomic (anti-sense) RNA using a mixture of three riboprobes directed to P, M and F genes. No significant differences were observed between the amount of genomic RNA in cells infected with rhMPV/ΔM2-2 and rhMPV (lanes 7 and 8, Figure 5F ). Thus, deletion of M2-2 altered the ratio between hMPV genomic RNA and mRNA.