293 and RH cells derived from human embryo kidney were infected by Venezuelan equine encephalitis and tick-borne encephalitis viruses and cDNA libraries representing cellular mRNAs induced or suppressed due to the infection were prepared using suppressive subtractive hybridization. Among the up-regulated clones the RT-PCR and Northern analyses revealed an unusual transcript of the spermidine/spermine N1-acetyltransferase (SSAT) gene that was shown to be an alternatively spliced form containing an additional 110-bp exon. The alternatively spliced transcript is polyadenylated and can be expected to yield only a truncated 71 amino acid polypeptide. This first evidence of the host gene alternatively spliced mRNA induction by RNA viruses raises the questions of its biological role, regulation mechanisms of alternative splicing, and significance for the virus life cycle.

The existence of a chromosome gene family containing at least one gene and one pseudogene was shown for the Na+,K+-ATPase /?-subunit. A partial structure of the pl-gene was determined, the coding part of which was completely homologous to cDNA of the Na+,K+-ATPase /II-subunit from HeLa cells [8]. The region encoding the putative protein transmembrane domain was shown to be bordered by two introns. The structure of a pseudogene (Bv/) was determined. This pseudogene is processed and contains multiple stop codons. Its homology to the /II-subunit cDNA from HeLa cells is about 88 %.