Molecular Analysis and Evolution of LMP1 Polimorphisms; Transcriptional Differences in Natural EDL1 Variants

GANTUZ, M; LORENZETTI M; PAOLA ANDREA CHABAY; PRECIADO MV

Zurich

Congreso; 17th International Symposium on EBV and Associated Diseases; 2016

EBV association

Introduction EBV infection in Argentina occurs at an early age and may develop infectious mononucleosis (IM). EBV is also related with lymphomas. LMP1 gene is polymorphic. Aim To study viral LMP1 variant distribution among children with EBV+ malignant and benign conditions as well as healthy carriers. Methods Oral secretions (OS) and blood cells (PBMC) from 30 children with IM, and biopsies from 14 EBV+ Reactive hyperplasia (RH) and 29 EBV+ lymphomas (L) were included. LMP1 sequences were amplified by nested PCR. Sequencing was performed. Luciferase expression was assayed in EDL1 variants. Phylogenetic analyses were made under Max. Likelihood, Bayesian and coalescent algorithms. Results EBV1 was predominant (75.8%). Phylogenetic reconstruction defined 4 EDL1 clades termed after B95.8, Cao, Raji and P3HR1. B95.8 clade was the most frequent (47%), but was not associated with lymphoma. Coinfection was assessed by cloning in 6 IM cases with different EDL1 variants in OS and PBMC. B95.8 was prevalent in PBMC. Mutations were found in transcription factor binding sites; the abolition of C/EBP caused a 3-fold diminish in EDL1 activity. Within coding region, 6 clades were defined (China1, China2, Med-, Alaskan, B95.8 and Argentine (Arg)). Arg clade, the most prevalent (46%), proved to be a Raji and China1 recombinant. Despite no pathology or compartment associations were observed for LMP1, the Arg clade showed a phylogeographic association with our region. LMP1 estimated evolution rate was 1,39x10-4 s/s/y (0.658-2.276x10-4 s/s/y, 95%HPD), positive selective pressure was detected in 8 codons and the TMRCA for Raji and Arg was estimated at 111 ybp (59-231 ybp, 95%HPD). Conclusion A clade of LMP1 variants circulating in Argentina was defined. LMP1 evolutionary rate was higher than expected for herpesviruses, positive selection may influence it. The TMRCA for Raji and the Arg variant agrees with African immigration and could explain the recombinant nature of the Arg variant.