Intragenic Recombination as a Mechanism of Genetic Diversity in Bluetongue Virus

Abstract

Bluetongue (BT), caused by Bluetongue virus (BTV), is an economically important disease affecting sheep, deer, cattle, and goats. Since 1998, a series of BT outbreaks have spread across much of southern and central Europe. To study why the epidemiology of the virus happens to change, it is important to fully know the mechanisms resulting in its genetic diversity. Gene mutation and segment reassortment have been considered as the key forces driving the evolution of BTV. However, it is still unknown whether intragenic recombination can occur and contribute to the process in the virus. We present here several BTV groups containing mosaic genes to reveal that intragenic recombination can take place between the virus strains and play a potential role in bringing novel BTV lineages.

Evidence for intragenic recombination and selective sweep in an effector gene of Phytophthora infestans

“…Hence, it is logical to expect that the number of intragenic recombination events may be similar to the number of intergenic ones although an unknown proportion of intragenic recombination may be deleterious or lethal. Despite this possibility, its role in the evolution of species, largely underestimated until recent advances in molecular and computation technologies, has been shown to be of great importance occurring in almost all species and kingdoms ranging from virus (He & Ding, 2012; He et al., 2010; Phan, Okitsu, Maneekarn, & Ushijima, 2007) to protists (Ferreira & Briones, 2012), fungi (Stergiopoulos et al., 2014), plants (Kelly et al., 2010; Ortega, Bošković, Sargent, & Tobutt, 2006; Städler & Delph, 2002), and animals (Godinho, Mendonça, Crespo, & Ferrand, 2006; Marthaler et al., 2014). In the current study, we have two lines of evidence to support the hypothesis that intragenic recombination also contributes to the high genetic variation and evolutionary potential of Avr3a.…”

Bluetongue virus genetic and phenotypic diversity: Towards identifying the molecular determinants that influence virulence and transmission potential

“…Interestingly it was found that several BTV strains isolated at different time points and from different geographical locations contained genome segments that appeared to be descended from common mosaic ancestors indicating that recombinant genes had become fixed amongst dominant strains in the field. This observation suggests (but does not prove) that the acquisition of the recombinant genes by these dominant field strains may have resulted in an increased evolutionary fitness of these viruses in the field (He et al, 2010).…”

“…Analysis of 690 complete BTV gene sequences available on Genbank, representing all of the genome segments of the virus has indicated that up to 1.6% of the analyzed sequences represented unique recombination events (He et al, 2010). Recombination was found to have occurred in all of the viral genome segments except segments 5 and 6, with recombinants having undergone either single, double or multiple cross-over events.…”

“…He et al, (2010) suggested that recombination may be facilitated by regions within the viral genome that are prone to the formation of RNA secondary structures. These regions could allow parenteral RNA segments from disparate origins to interact with each other, thereby allowing recombination to occur.…”

“…Bluetongue virus evolves through a combination of genetic drift/shift as well as intragenic recombination (Bonneau et al, 2001;He et al, 2010;Samal et al, 1987a;Samal et al, 1987b;Stott et al, 1987). These evolutionary processes result in the generation of quasispecies populations in the host or vector, from which variants with optimal fitness may be selected under different environmental conditions.…”