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Type Species |
(HRSV) |
List of Species Demarcation Criteria in the Genus
HRSV and MPV are distinguished by host range (humans versus mice) and a lack of cross-neutralization. Amino acid sequence relatedness between these two viruses varies from undetectable to intermediate, depending on the protein (for example, the NS1 and NS2 proteins lack demonstrable relatedness, whereas the N or F proteins share 60% or 40% identity, respectively). Their gene maps differ only in the absence of the M2/L gene overlap in MPV. BRSV differs from HRSV in host range, specifically cattle versus humans, but the difference is not absolute. For example, both viruses grow efficiently in cultured human or bovine cells, although some specificity may be evident. In chimpanzees, HRSV replicates efficiently, is transmissible and is pathogenic, whereas BRSV is very attenuated and nonpathogenic. The two viruses share considerable sequence and antigenic relatedness, but also can clearly be distinguished on either basis. For example, the N or F proteins are each 81% identical between BRSV and HRSV, compared to 96% or 89% identical, respectively, among different HRSV strains. Antiserum against one virus will cross-neutralize the other with a 6 to 64-fold reduction in efficiency. There are two antigenic subgroups of HRSV, called A and B, which exhibit amino acid sequence identity ranging from 96% (N) to 53% (G), and which are approximately 50% or 5% related antigenically in the F or G protein, respectively, with the overall difference in reciprocal cross-neutralization being up to four-fold. Comparable antigenic dimorphism also may exist for BRSV.
Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus names, genome sequence accession numbers [ ], and assigned abbreviations ( ) are:
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Bovine respiratory syncytial virus |
[M58350, M82816, S40504, U15937, U15938] |
(BRSV) |
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Human respiratory syncytial virus |
(HRSV) | |
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Human respiratory syncytial virus A2 |
[M74568] |
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Human respiratory syncytial virus B1 |
[AF013254] |
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Human respiratory syncytial virus S2 |
[U39662] |
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Murine pneumonia virus |
[D11128, D11130, D10331, U66893, U09649] |
(MPV) |
Tentative Species in the Genus
Caprine and ovine strains of BRSV also have been described but might represent, with BRSV, a subgroup of ruminant strains rather than different species.
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