title: Comparison of virological profiles of respiratory syncytial virus and rhinovirus in acute lower tract respiratory infections in very young Chilean infants, according to their clinical outcome.
abstract: BACKGROUND
  Respiratory syncytial virus (RSV) and rhinovirus (HRV) are the main cause of acute lower respiratory tract infections (ALRTIs) in infants. Viral and host-related risk factors for severe disease have also not been clearly established.
  
  
  OBJECTIVE
  To assess whether certain viral features of RSV and, or HRV are associated with severe ALRTI.
  
  
  METHODS
  RSV and HRV were studied in nasopharyngeal samples of infants by immunofluorescence, Luminex(®) and/or real-time RT-PCR assays. Quantitation and genotyping of RSV and HRV by PCR were done.
  
  
  RESULTS
  Of 124 virus positive specimens, 74 (59.7%) had RSV; 22 (17.7%) HRV and 28 (22.6%) RSV-HRV co-infection. Hospitalization was required in 57/74 RSV infants (77.0%); in 10/22 HRV cases (45.5%) (p=0.006) and in 15/28 co-infected by both viruses (53.6%) (p=0.003). Severe cases were 33/74 (44.6%) RSV infections, 2/22 HRV cases (9.1%), (p<0.002) and 6/28 (21.4%) patients co-infected by RSV-HRV (p<0.026). Three genotypes (NA1, B7, B9) of RSV circulated during the study. In 33 severe infants, NA1 was detected in 19 cases (57.6%); B7 in 13 (39.4%) and B9 in 1 (3.0%) (p<0.01; OR=10.0). RSV loads were similar between outpatients and hospitalized infants (p=0.7) and among different severities (p=0.7). NA1 loads were higher than other strains (p=0.049). Three geno-groups of HRV circulated homogeneously.
  
  
  CONCLUSIONS
  In very young infants, RSV cause more severe disease than HRV. Co-infection does not increase the severity of illness. NA1 RSV genotype was associated with major frequency of hospitalization, severe respiratory disease and higher viral load.
authors.affiliation: Program of Virology of the Institute of Science in Biomedicine, Faculty of Medicine, University of Chile, Santiago, Chile.
authors.forename: Vivian
authors.initials: V
authors.lastname: Luchsinger
authors.affiliation: Program of Virology of the Institute of Science in Biomedicine, Faculty of Medicine, University of Chile, Santiago, Chile.
authors.forename: Sandra
authors.initials: S
authors.lastname: Ampuero
authors.affiliation: Department of Pediatrics, Hospital Roberto del Río, Faculty of Medicine, University of Chile, Santiago, Chile.
authors.forename: M Angélica
authors.initials: MA
authors.lastname: Palomino
authors.affiliation: Program of Virology of the Institute of Science in Biomedicine, Faculty of Medicine, University of Chile, Santiago, Chile.
authors.forename: Jonás
authors.initials: J
authors.lastname: Chnaiderman
authors.affiliation: Program of Virology of the Institute of Science in Biomedicine, Faculty of Medicine, University of Chile, Santiago, Chile.
authors.forename: Jorge
authors.initials: J
authors.lastname: Levican
authors.affiliation: Program of Virology of the Institute of Science in Biomedicine, Faculty of Medicine, University of Chile, Santiago, Chile. Electronic address: agaggero@med.uchile.cl.
authors.forename: Aldo
authors.initials: A
authors.lastname: Gaggero
authors.affiliation: Program of Virology of the Institute of Science in Biomedicine, Faculty of Medicine, University of Chile, Santiago, Chile. Electronic address: clarrana@med.uchile.cl.
authors.forename: Carmen E
authors.initials: CE
authors.lastname: Larrañaga
mesh_terms: D002677:Chile / Q000453:epidemiology; D005260:Female; D005838:Genotype; D006801:Humans; D007118:Immunoassay; D007223:Infant; D008297:Male; D009305:Nasopharynx / Q000821:virology; D010850:Picornaviridae Infections / Q000453:epidemiology / Q000473:pathology / Q000821:virology; D060888:Real-Time Polymerase Chain Reaction; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000473:pathology / Q000821:virology; D018113:Respiratory Syncytial Virus, Human / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000473:pathology / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012229:Rhinovirus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D016896:Treatment Outcome; D019562:Viral Load
keywords: ALTRI; Respiratory syncytial virus; Rhinovirus; Severe infantile respiratory infection