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Category: Viruses and Viral Pathogenesis
Rhinovirus, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555819439/9781555819422.ch47-1.gif /docserver/preview/fulltext/10.1128/9781555819439/9781555819422.ch47-2.gifAbstract:
Rhinoviruses (RVs), members of the Picornaviridae family (1), constitute the largest group of respiratory viruses. RVs are recognized as causing more than 50% of all acute respiratory infections and represent the single most important causative agent of common colds. The name “rhinovirus” stems from the virus's special adaptation to infect the nasopharynx. It was already known in 1930 that “colds” were easily transmitted from human to human and to apes, and that the responsible agent was probably a virus (2, 3), but it was not until 1956 that the first RV was discovered by isolation in cell culture (4, 5). The discovery of the low temperature optimum (32–35°C) for viral replication (6), the development of sensitive primary human embryonic lung cell cultures (WI-38 and MRC-5), and the continuous H1-Hela cell line (7, 8) facilitated the isolation, classification, and epidemiological and biological studies of RVs. A total of 100 serotypes were identified over the next 30 years (9). The first complete genome sequence was determined for RV14 in 1984 (10), a reverse genetics system was developed in 1985 (11), and the X-ray crystallographic structures of the viral capsids of five serotypes (1A, 2, 3, 14, and 16) were solved soon afterward (12–17). The recent use of more sensitive RT-PCR-based molecular assays for RV identification has generated clear evidence that RV infections are also common causes of more severe lower respiratory illnesses, such as bronchiolitis, pneumonia, exacerbations of asthma, and other chronic lung diseases (18–22). RT-PCR has also led to the discovery of more than 50 genotypes of previously unrecognized RVs that belong to a new species (RV-C). These viruses escaped traditional culture-based detection (23–26). This discovery has promoted a new wave of interest in RV research.
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Receptor groups of rhinoviruses. Majority of RV serotypes (63 RV-A and all 25 RV-B) use ICAM-1 as the receptor. The remaining 12 RV-A serotypes bind to low-density lipoprotein receptor (LDLR) family proteins. RV87 was originally misidentified as a RV and has been reclassified as an enterovirus (EV-D68). The receptor for RV-C has been recently identified as cadherin-related family member 3 (CDHR3) protein.
Receptor groups of rhinoviruses. Majority of RV serotypes (63 RV-A and all 25 RV-B) use ICAM-1 as the receptor. The remaining 12 RV-A serotypes bind to low-density lipoprotein receptor (LDLR) family proteins. RV87 was originally misidentified as a RV and has been reclassified as an enterovirus (EV-D68). The receptor for RV-C has been recently identified as cadherin-related family member 3 (CDHR3) protein.
(A) Schematic drawing of ICAM-1, the receptor used by the major group RVs. S-S represents disulfide bridges, and small circles represent sites of glycosylation. (B) Key features of the structure of a human RV. The virion shell consists of 12 pentamers, one of which has been removed to show the approximate location of the RNA packed tightly into a central cavity. Each pentamer, in turn, consists of five wedge-shaped protomer subunits. The canyon (shaded) is shown encircling the five-fold axis of the pentamer; the hydrophobic (drug-binding) pocket is indicated below the floor of the canyon in VP1. (C) A side view of the pentamer showing the spatial relationship between the receptor-binding site and the hydrophobic pocket. An ion, located at each pentamer center in serotypes 1A, 14, and 16 is tentatively identified as calcium.
(A) Schematic drawing of ICAM-1, the receptor used by the major group RVs. S-S represents disulfide bridges, and small circles represent sites of glycosylation. (B) Key features of the structure of a human RV. The virion shell consists of 12 pentamers, one of which has been removed to show the approximate location of the RNA packed tightly into a central cavity. Each pentamer, in turn, consists of five wedge-shaped protomer subunits. The canyon (shaded) is shown encircling the five-fold axis of the pentamer; the hydrophobic (drug-binding) pocket is indicated below the floor of the canyon in VP1. (C) A side view of the pentamer showing the spatial relationship between the receptor-binding site and the hydrophobic pocket. An ion, located at each pentamer center in serotypes 1A, 14, and 16 is tentatively identified as calcium.
(A) RNA genome of a human RV. P1, P2, and P3 refer to precursor proteins that are subsequently processed to produce 11 end products. (B) Cleavage of the polyprotein is accomplished by two viral proteases, 2A and 3C. The 2A protease co-translationally releases the coat precursor, P1, from nascent polyprotein, whereas the 3C (or precursor 3CD) protease cleaves all the remaining precursors and intermediates except for VP0 (1A-1B). Cleavage of VP0 to VP4 (1A) and VP2 (1B), maturation cleavage, occurs only after the RNA has been packaged in the protein shell. The VP0 cleavage site lies buried inside the shell near the RNA; the active site for this cleavage is not yet precisely known and might include bases in the RNA genome. The amino termini of coat proteins P1 and VP4 are blocked by a myristoyl group. Cis-cleavage of the N-terminus of 2A is shown by an arrow; black triangles indicate 3C cleavage sites.
(A) RNA genome of a human RV. P1, P2, and P3 refer to precursor proteins that are subsequently processed to produce 11 end products. (B) Cleavage of the polyprotein is accomplished by two viral proteases, 2A and 3C. The 2A protease co-translationally releases the coat precursor, P1, from nascent polyprotein, whereas the 3C (or precursor 3CD) protease cleaves all the remaining precursors and intermediates except for VP0 (1A-1B). Cleavage of VP0 to VP4 (1A) and VP2 (1B), maturation cleavage, occurs only after the RNA has been packaged in the protein shell. The VP0 cleavage site lies buried inside the shell near the RNA; the active site for this cleavage is not yet precisely known and might include bases in the RNA genome. The amino termini of coat proteins P1 and VP4 are blocked by a myristoyl group. Cis-cleavage of the N-terminus of 2A is shown by an arrow; black triangles indicate 3C cleavage sites.
(A) Diagram representing virion architecture and assembly. (B) The mature virion contains four major proteins (VP1 [1D], 2 [1B], 3 [1C], and 4 [1A],) plus traces of VP0, representing residual precursor following the maturation cleavage required for acquisition of infectivity.
(A) Diagram representing virion architecture and assembly. (B) The mature virion contains four major proteins (VP1 [1D], 2 [1B], 3 [1C], and 4 [1A],) plus traces of VP0, representing residual precursor following the maturation cleavage required for acquisition of infectivity.
Overview of the RV infection cycle.
Overview of the RV infection cycle.
Cytopathic effect (CPE) in H1-Hela and WI-38 cells caused by RV infection. Cells were exposed to 100 PFU of human RV type 16 (RV16) per cell and incubated at 35°C. Infected HeLa cells became rounded and detached from growth surface by 12 hours but WI-38 cells required 48 hours to develop CPE.
Cytopathic effect (CPE) in H1-Hela and WI-38 cells caused by RV infection. Cells were exposed to 100 PFU of human RV type 16 (RV16) per cell and incubated at 35°C. Infected HeLa cells became rounded and detached from growth surface by 12 hours but WI-38 cells required 48 hours to develop CPE.
Proposed pathogenesis of symptoms associated with RV infection.
Proposed pathogenesis of symptoms associated with RV infection.