Analyses of the Kroon Virus Major Capsid Gene and Its Transcript Highlight a Distinct Pattern of Gene Evolution and Splicing among Mimiviruses

Paulo Victor Miranda Boratto; Fábio Pio Dornas; Lorena Christine Ferreira da Silva; Rodrigo Araújo Lima Rodrigues; Graziele Pereira Oliveira; Juliana Reis Cortines; Betânia Paiva Drumond; Jônatas Santos Abrahão

doi:10.1128/JVI.01782-17

Analyses of the Kroon Virus Major Capsid Gene and Its Transcript Highlight a Distinct Pattern of Gene Evolution and Splicing among Mimiviruses

J Virol. 2018 Jan 2;92(2):e01782-17. doi: 10.1128/JVI.01782-17. Print 2018 Jan 15.

Authors

Paulo Victor Miranda Boratto¹, Fábio Pio Dornas¹, Lorena Christine Ferreira da Silva¹, Rodrigo Araújo Lima Rodrigues¹, Graziele Pereira Oliveira¹, Juliana Reis Cortines², Betânia Paiva Drumond¹, Jônatas Santos Abrahão³

Affiliations

¹ Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
² Instituto de Microbiologia Paulo de Góes, Departamento de Virologia-Centro de Ciências da Saúde, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ, Brazil.
³ Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil jonatas.abrahao@gmail.com.

Abstract

The inclusion of Mimiviridae members in the putative monophyletic nucleocytoplasmic large DNA virus (NCLDV) group is based on genomic and phylogenomic patterns. This shows that, along with other viral families, they share a set of genes known as core or "hallmark genes," including the gene for the major capsid protein (MCP). Although previous studies have suggested that the maturation of mimivirus MCP transcripts is dependent on splicing, there is little information about the processing of this transcript in other mimivirus isolates. Here we report the characterization of a new mimivirus isolate, called Kroon virus (KV) mimivirus. Analysis of the structure, synteny, and phylogenetic relationships of the MCP genes in many mimivirus isolates revealed a remarkable variation at position and types of intronic and exonic regions, even for mimiviruses belonging to the same lineage. In addition, sequencing of KV and Acanthamoeba polyphaga mimivirus (APMV) MCP transcripts has shown that inside the family, even related giant viruses may present different ways to process the MCP mRNA. These results contribute to the understanding of the genetic organization and evolution of the MCP gene in mimiviruses.IMPORTANCE Mimivirus isolates have been obtained by prospecting studies since 2003. Based on genomic and phylogenomic studies of conserved genes, these viruses have been clustered together with members of six other viral families. Although the major capsid protein (MCP) gene is an important member of the so-called "hallmark genes," there is little information about the processing and structure of this gene in many mimivirus isolates. In this work, we have analyzed the structure, synteny, and phylogenetic relationships of the MCP genes in many mimivirus isolates; these genes showed remarkable variation at position and types of intronic and exonic regions, even for mimiviruses belonging to the same lineage. These results contribute to the understanding of the genetic organization and evolution of the MCP gene in mimiviruses.

Keywords: KV; Megavirales; capsid; giant virus; isolation; mimivirus; splicing.

MeSH terms

Capsid Proteins / genetics*
Evolution, Molecular*
Gene Expression Regulation, Viral*
Genome, Viral
Mimiviridae / classification
Mimiviridae / genetics*
Mimiviridae / isolation & purification
Mimiviridae / ultrastructure
Phylogeny
RNA Splicing*
RNA, Viral
Transcription, Genetic*
Virus Replication
Water Microbiology

Substances

Capsid Proteins
RNA, Viral