Virulence potential of fusogenic orthoreoviruses

Abstract

Several severe respiratory virus infections that have emerged during the past decade originated in animals, including bats. In Indonesia, exposure to bats has been associated with increased risk of acquiring orthoreovirus infection. Although orthoreovirus infections are mild and self-limiting, we explored their potential for evolution into a more virulent form. We used conventional virus culture, electron microscopy, and molecular sequencing to isolate and identify orthoreoviruses from 3 patients in whom respiratory tract infection developed after travel to Indonesia. Virus characterization by plaque-reduction neutralization testing showed antigenic similarity, but sequencing of the small segment genes suggested virus reassortment, which could lead to increased virulence. Bats as a reservoir might contribute to virus evolution and genetic diversity, giving orthoreoviruses the potential to become more virulent. Evolution of this virus should be closely monitored so that prevention and control measures can be taken should it become more virulent.

Figure 1

Phylogenetic tree of orthoreoviruses based on partial sequence alignment of the cell attachment protein (S1 gene segment). GenBank accession number for each sequence is in parentheses after the virus name. Numbers at nodes indicate bootstrap values based on 1,000 replicates. Dots indicate viruses isolated from 3 travelers who had returned from Indonesia to Hong Kong during 2007–2010. Scale bar indicates nucleotide substitutions per site. ARV, avian reovirus; NBV, Nelson Bay virus.

Figure 2

Phylogenetic tree of orthoreoviruses based on partial sequence alignment of the major inner capsid protein (S2 gene segment). GenBank accession number for each sequence is in parentheses after the virus name. Numbers at nodes indicate bootstrap values based on 1,000 replicates. Dots indicate viruses isolated from 3 travelers who had returned from Indonesia to Hong Kong during 2007–2010. Scale bar indicates nucleotide substitutions per site. ARV, avian reovirus; MRV, mammalian reovirus; NBV, Nelson Bay virus.

Figure 3

Phylogenetic tree of orthoreoviruses based on partial sequence alignment of the nonstructural protein (S3 gene segment). GenBank accession number for each sequence is in parentheses after the virus name. Numbers at nodes indicate bootstrap values based on 1,000 replicates. Dots indicate viruses isolated from 3 travelers who had returned from Indonesia to Hong Kong during 2007–2010. Scale bar indicates nucleotide substitutions per site. ARV, avian reovirus; NBV, Nelson Bay virus.

Figure 4

Phylogenetic tree of orthoreoviruses based on partial sequence alignment of the major outer capsid protein (S4 gene segment). GenBank accession number for each sequence is in parentheses after the virus name. Numbers at nodes indicate bootstrap values based on 1,000 replicates. Dots indicate viruses isolated from 3 travelers who had returned from Indonesia to Hong Kong during 2007–2010. Scale bar indicates nucleotide substitutions per site. ARV, avian reovirus; BRV, baboon reovirus; NBV, Nelson Bay virus; RRV, reptilian reovirus.

Figure 5

Electron micrograph of orthoreovirus HK50842/10. Scale bar = 200 nm.