Biology Reference
In-Depth Information
The large number of serologically different rhinovirus types has
precluded the development of vaccines, and antiviral agents have still
not reached clinical application. The latter are targeted to the viral
capsid and prevent uncoating by binding into a hydrophobic pocket
or to virally encoded enzymes, such as the proteases.
Rhinovirus Receptor Groups and Subgenera
Early on, Lonberg-Holm and colleagues noted that some human rhi-
novirus serotypes competed for binding to the cell surface, suggest-
ing that they use the same cellular receptors.
7,8
Based on a more
extensive analysis using blockage by a monoclonal antibody, 91
serotypes were assigned to the major receptor group and 10 serotypes
to the minor receptor group.
9-11
The major and the minor group
receptors were subsequently shown to be identical to the intercellular
adhesion molecule 1 (ICAM-1)
12-14
and members of the low-density
lipoprotein receptor (LDLR) superfamily, respectively. The latter
includes LDLR, the very-LDLR (VLDLR) and the LDLR related
protein (LRP).
15-18
HRV87 could not be allocated to either group,
and, based on phylogeny, it was later found to be a prime strain of the
acid-labile enterovirus EV68.
19-21
This classification has been gener-
ally adopted by the scientific community. However, recently HRV23
and HRV25 were found to be minor group viruses.
22
Since serotype
Hanks and HRV21, as well as HRV8 and HRV95, exhibit extensive
immunologic cross-reactivity and high amino acid sequence similarity
of VP1,
20,23
they can be considered as two single serotypes. Therefore,
there are now 87 major group HRVs and 12 minor group HRVs
(HRV1A and HRV1B being regarded as two separate strains).
Another means of HRV classification emerged from the observa-
tion that different rhinovirus serotypes were differently sensitive
towards a panel of antivirally active compounds; many of these are
derived from isoxazol, and were termed “WIN-compounds” since they
were synthesized by the Sterling Winthrop company.
24
Whereas some
HRVs are neutralized by compounds with a long aliphatic chain, oth-
ers preferentially bind shorter compounds
25
; this gave rise to catalogu-
ing HRVs as antiviral groups A and B.
26
No correlation between these
antiviral groups and the two receptor groups was found. Nevertheless,
