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Respiratory Syncytial Virus
Respiratory Syncytial Virus at 50
a report by
Leonard R Krilov, MD, FAAP
Chief of Pediatric Infectious Diseases and Vice Chairman of Pediatrics, Winthrop University Hospital, and
Professor of Pediatrics, State University of New York at Stony Brook
In the 50 years since the initial discovery of chimpanzee coryza agent and the RSV infection is ubiquitous, with half of children infected by their first
recognition that the virus was primarily a human pathogen—leading to it birthday and virtually all children having had at least one RSV infection
being re-named respiratory syncytial virus (RSV)
1,2
—much has been learned by their second birthday.
3
Re-infection occurs throughout the patient’s
about the structure of the virus and its epidemiology, transmission, lifetime, despite the presence of circulating neutralizing antibodies.
laboratory detection, and prevention of severe disease in high-risk children. However, with increasing age the illness tends to be more limited to the
However, much remains to be learned about this ‘simple’ virus. Only upper respiratory tract. Still, recent studies have demonstrated significant
supportive treatment is available, even in critically ill infants. The morbidity from RSV infection in elderly and high-risk adults.
4
development of effective antiviral and anti-inflammatory treatment regimens
are needed. The role of RSV infection in infancy in the development of
subsequent wheezing also needs to be further elucidated. Finally, although …although progress has been made, the
progress has been made, the development of a safe and effective vaccine to
development of a safe and effective
prevent severe RSV disease remains at least five to 10 years away. This review
will address our current understanding of this virus and areas to be pursued. vaccine to prevent severe respiratory
syncytial virus disease remains at least
RSV is a single-stranded, negative-sense, enveloped virus of the
paromyxovirus family, genus Pneumoviridae. The viral RNA encodes for five to 10 years away.
eight structural proteins and two of unknown function (NS1 and NS2). Of
the RSV proteins, the fusion (F) and glycoprotein (G) are the major surface
proteins and appear to be critical to viral infectivity and the pathogenesis of In children, the burden of RSV is such that it is the leading cause of
RSV disease. The G protein appears to play an important role in the specific pediatric hospitalization in the winter months, accounting for >100,000
binding of the virus to cell surface receptors, while the F protein is involved hospitalizations per year in the US.
5,6
The vast majority of hospitalized
in the fusion of viral and cell membranes during the infection process, as children (>80%) are less than one year old and >50% are under six
well as in cell-to-cell fusion. Host antibody responses to these proteins are months of age. Based on population studies, ~2–8% of all newborns
capable of neutralizing the virus and are thought to play a major role in are hospitalized during their first year of life due to RSV lower respiratory
protection against the development of severe RSV disease. Cell-mediated tract infection (LRTI). Additionally, groups of children at increased risk
immunity is required for clearing the acute RSV infection. for severe RSV infection have been identified (see Table 1). In these
infants, hospitalization rates are two- to three-fold higher than in
no-risk groups and, when hospitalized, they have higher rates of
Leonard R Krilov, MD, FAAP, is Chief of Pediatric Infectious
Diseases and Vice Chairman of Pediatrics at Winthrop University
intensive care unit (ICU) admission and mechanical ventilation and
Hospital in Mineola, New York, and Professor of Pediatrics at the increased duration of hospitalization. Their increased risk relates to
State University of New York at Stony Brook School of Medicine.
decreased levels of maternal antibodies, underdeveloped or damaged
He is a Fellow of the American Academy of Pediatrics (AAP),
the Infectious Diseases Society of America (IDSA), and the
lungs, increased pulmonary blood flow, and/or decreased ability to clear
Pediatric Infectious Disease Society (PIDS), and an elected the virus. Hospitalization rates are much higher for these high-risk
member of the Society for Pediatric Research (SPR) and the
children, but, given that the vast majority of newborns are healthy,
American Pediatric Society (APS); he is also Co-Chair of the
Infectious Disease Committee for AAP Chapter 2, District 2, and Past President of the Nassau
full-term infants, most hospitalizations related to RSV infection are in
Pediatric Society. Dr Krilov has had a career-long interest in clinical infectious diseases and previously well babies.
respiratory viral infections and has been involved in many of the respiratory syncytial virus
prevention trials and influenza vaccine trials. He has authored more than 100 original articles and
book chapters. Dr Krilov is Editor of Concise Reviews in Infectious Disease, eMedicine, and
Two subtypes of RSV, A and B, have been described based on differences
Infectious Disease in Practice, and is a reviewer for a number of pediatric and infectious disease detected by monoclonal antibodies, but their importance in community
journals, including Pediatrics, Journal of Pediatrics, and the Pediatric Infectious Disease Journal.He
outbreaks and/or re-infection remains unclear.
7
received his medical training at Columbia University before completing a pediatric internship and
residency at Johns Hopkins Hospital in Baltimore, Maryland, and a fellowship in pediatric
infectious disease at Children’s Hospital Boston, Massachusetts. Transmission of RSV occurs by droplets, large particles, hand-to-hand
contact, and fomites. RSV can survive for up to six to 12 hours on
environmental surfaces.
8
34 © T OUCH BRIEFINGS 2007
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