Viral RNAs detected in virions of porcine adenovirus type 3.

It has been demonstrated that cellular and viral RNAs were packaged in the virions of human cytomegalovirus (CMV) and herpes simplex virus 1 (HSV 1), members of the Herpesviridae family, both of which are enveloped double-stranded DNA viruses. Here, we provide evidence suggesting that RNAs are packaged in the virions of porcine adenovirus type 3 (PAdV-3), which is a member of the Adenoviridae family, a non-enveloped double-stranded DNA virus. The RNAs packaged in PAdV-3 virions were enriched in the size range of 300-1000 bases long. By reverse transcription (RT) of RNAs isolated from purified PAdV-3 virions, PCR amplification, and DNA sequence analysis of PCR products, we determined the identities of some viral RNAs contained in PAdV-3 virions. The results indicated that the RNAs representing transcripts from E1A, E1B, DNA binding protein (DBP), DNA polymerase (POL), E4 and some of the late genes including pIIIA, pIII, pV, Hexon, 33 K, and fiber were detected from purified PAdV-3 virions. In contrast, we could not detect the RNAs representing transcripts of precursor terminal protein (pTP), 52 kDa, pX, or 100-kDa protein genes in purified virions. Because the transcripts of pIX, IVa2, E3, protease, pVI, pVII, and pVIII overlap with those of other genes in PAdV-3, we could not definitely conclude that RNAs representing these transcripts were packaged in virions although the expected DNA fragments were produced by RT-PCR in the RNAs isolated from purified virions.