RSV plays a major role in respiratory infection among the childhood population, especially infants and younger children. It is the leading viral agent respiratory tract disease worldwide, causing bronchiolitis and pneumonia in infants and young children. There are about 100,000 cases and 4,500 deaths yearly of RSV infections in the United States (1). Typically, all children are infected with RSV by age 2 to 3; however, the infections can reemerge up to 5 to 6 per year. RSV was first extracted from chimpanzees that were showing upper respiratory tract disease as an agent in 1956 (1). The chimpanzees had an upper respiratory tract illness in addition to coryza, runny nose, and malaise. The humans that interacted with these chimpanzees soon also had mild upper respiratory tract illness. A Long strain was recovered in children who suffered from bronchopneumonia while a Schneider strain was recovered from a patient with croup. Together, a group of scientists combined all these strains into a term called “respiratory syncytial virus” (3).
RSV is an enveloped, cytoplasmic, pleomorphic virus with negative single stranded RNA (3). This virus belongs in the paramuxoviridae family and in the subfamily Penumovirinae. It has a single serotype and two antigenic subtypes, A or B. In total, 8 out of the total ten RSV proteins are seen in infected cells and virions, eight being structural and two being non-structural (3). The viral envelope has three glycoproteins: G, F, and SH protein (4). In addition, RSV has 5 other structure proteins which include L, N, P, M and M2-1 (4). Two non-structural proteins: NS1 and NS2 are identified with RSV, but it is still unknown whether these two proteins are a part of the assembled virus particles (4).
RSV virions have a spherical shape with about 80-350nm in diameter and up to 10 nanometer in length (2). They have a helical nucleocapsid fitted in a lipoprotein envelope acquired from the host cell plasma membrane during budding. This virus also has the classic trademark of “spike-like” glycoprotein projections on the outside of the envelope.
How RSV works:
. The F (fusion) glycoprotein is responsible for membrane fusion such as viral penetration and syncytium formation.
The G (glycoprotein) protein is responsible for viral attachment and a major antigenic determinant of RSV since it induces protective antibodies (3).
The SH (small hydrophobic) protein, matrix protein (M), and the M2 protein are envelope-associated proteins that are not involved in viral attachment or syncytium formation (3). Other proteins such as the nucleoprotein (N), phosphoprotein (P), and the large nucleoprotein (L) are in the nucleocapsid. NS-1 and NS-2 are non-structure protein that is only found in the infected cells but not present in virions (3).
RSV comes into the airway epithelium from the apical side only and aims to destroy the ciliated epithelia cells (4). Then RSV buds and releases the...