INTRODUCTION

The aim of the study was to reconstruct alphaviruses isolated in Uganda and Tanzania prior to their global spread and dating back to the middle of the last century. We propose that analysis of their genomes could clarify the features and direction of the molecular evolution for these viruses in modern world.

MATERIALS AND METHODS

Archival samples of Chikungunya (CHIKV) and Semliki Forest (SFV) viruses were restored by cultivation on Vero E6 cells. The isolates were identified by RT-PCR followed by sequencing. Whole genome sequences were determined by NGS sequencing and used for their phylogenetic analysis.

RESULTS AND DISCUSSION

The presence of two representatives of the genus Alphavirus, namely CHIKV and SFV, was identified in the studied archival sample of CHIKV. In the 1942 archival sample, only SFV was found. All isolates were able to replicate highly efficiently on cell cultures C6/36, Vero E6, 293 and SPEV with the development of CPE and cause pathomorphological changes in mice typical for these alphaviruses. Their whole genome sequences have been determined. Phylogenetic analysis showed that the isolated isolates clustered with typical African CHIKV and SFV strains. The totality of the available data suggests that the recovered and sequenced isolates can be attributed to the oldest known strains of SFV and CHIKV, dating back to 1942 and 1953, preserved in laboratory collections. The absence in the CHIKV genome of mutations V 264 A in the E 2 gene and K211 E, M269V in the E1 gene, which are associated with the occurrence of the modern global outbreak of chikungunya fever further confirms the obtained results.

CONCLUSION

Isolates of the Semliki forest and chikungunya viruses were restored from archival laboratory samples presumably dating back to 1942 and 1953, their virological characterization was carried out, followed by phylogenetic analysis of their complete genome sequences.