Mammalian Orthoreovirus Reassortment Proceeds with Little Constraint on Segment Mixing.

Segmentation of viral genomes provides the potential for genetic exchange within coinfected cells. However, for this potential to be realized, coinfecting genomes must mix during the viral life cycle. The efficiency of reassortment, in turn, dictates its potential to drive evolution.

A method for the unbiased quantification of reassortment in segmented viruses.

Reassortment of segmented viruses can be an important source of genetic diversity underlying viral evolution and emergence. Methods for the quantification of reassortment have been described but are often cumbersome and best suited for the analysis of reassortment between highly divergent parental strains. While it is useful to understand the potential of divergent parents to reassort, outcomes of such heterologous reassortment are driven by differential selection acting on the progeny and are typically strain specific.

Dysregulation of M segment gene expression contributes to influenza A virus host restriction.

The M segment of the 2009 pandemic influenza A virus (IAV) has been implicated in its emergence into human populations. To elucidate the genetic contributions of the M segment to host adaptation, and the underlying mechanisms, we examined a panel of isogenic viruses that carry avian- or human-derived M segments. Avian, but not human, M segments restricted viral growth and transmission in mammalian model systems, and the restricted growth correlated with increased expression of M2 relative to M1.