Paramyxoviridae

1. Paramyxoviridae All members initiate infection in RT Parainfluenza & RSV Remain limited to respiratory epithelium Mumps & measles become disseminated throughout the body and produce generalized disease

2. PARAMYXOVIRIDAE

4. PARAMYXOVIRIDAETwo sub- families • Paramyxovirinae • Pneumovirinae

5. The Paramyxovirinae subfamily is divided into 4 genera, 3 of which are important: • Genus respirovirus:which include parainfluenza viruses 1 & 3 viruses • Genus Rubulaviruswhich include parainfluenza virus 2 &4 as well as mumps virus • Genus morbilliviruswhich include the measles (rubeola) virus

6. The Pneumovirinae subfamily is divided into two genera: 1. Genus pneumovirus which include respiratory syncytial virus RSV 2. Genus metapneumovirus which include: human metapneumovirus

7. Human Metapneumovirus The human metapneumovirus which is a respiratory pathogen first described in 2001. It appears to be widespread in young adults & older persons. Human metapneumovirus is able to cause a wide range of respiratory illnesses from MILD UR TO SEVERE LRT DISEASE

8. MORPHOLOGY • The paramyxoviruses are enveloped particles, • Large (150-300 nm in diameter). • The viral genome is composed of: • a negative sense • linear • single stranded, • non segmented RNA molecule.

9. MORPHOLOGY • Structural proteins are complexed with RNA to form the nucleocapsid. • The nucleocapsid is surrounded by a lipid envelope that is superimposed with spikes(glycoprotein in nature).

10. MORPHOLOGY • These spikes differentiated into two types: - “haemagglutinin-neuraminidase” spike (HN) - “fusion” (F) spike.

11. MORPHOLOGY “HN” and “F” spikes are both antigenic, They are responsible for: - host cell attachment, - mediation of membrane fusion, - haemolysin activity • The are key factors in infection and pathogenesis.

12. Characteristics of the genera in the subfamilies of the family Paramyxoviridae

13. The activities of the surface glycoprotein • F glycoprotein …. Also carries Hemolysin activity • HN glycoprotein ….Hemagglutination and neuraminidase activities • Hemagglutination of erythrocytes is more efficient by H glycoprotein that lacks neuraminidase activity

14. The difference between the orthomyxo & paramyxoviruses

15. Parainfluenza Viruses • Parainfluenza viruses are ubiquitous and cause common respiratory illness of varying severity in all age groups • Transmission: droplet

16. Parainfluenza Viruses • TYPE 1,2,& 3are particularly considered major pathogens of severe respiratory tract disease in infants & young children • Type 4 does not cause severe disease even on primary infection.

17. Parainfluenza Viruses • 1ry infections in young children usually result in • Rhinitis • Pharyngitis • However children with primary infection caused by serotypes 1,2 or 3 may have serious illness ranging from: • Laryngeotracheobronchitis (croup/stridor) • Bronchiolitis & pneumonia mainly type 3 age < 6month

18. MOST IMPORTANT Acute laryngeo-tracheobronchitis • Croup : stridor • Caused mainly byserotype 1 & 2 • age 6 -18 month • incubation period 2 to 6 days • subglottal sweling, which endangers the airway. • The principal differential diagnosis is epiglottitis caused by Haemophilus influenza.

19. PARAMYXOVIRIDAE Two sub- families • Paramyxovirinae • Genus respirovirus: Parainfluenza 1 &3 • Genus Rubulavirus Parainfluenza 2 & 4 and mumps virus • Genus morbillivirus measles virus • Pneumovirinae • Pneumovirus • RSV • Metapneumovirus • metapneumovirus

20. Pneumovirinae 1. Genus pneumovirus which include respiratory syncytial virus RSV 2. Genus metapneumovirus which include: human metapneumovirus

21. Respiratory syncytial virus

22. Respiratory syncytial virus • RSV is a paramyxovirus that lacks: • haemagglutinin & • neuraminidase activity. • The F peplomer as well lacks • haemolysin activity.

23. Respiratory syncytial virus • RSV is transmitted via droplet infection. • Viral replication occurs in the epithelial cells of the nasopharynx. • Viraemia has not been detected.

24. Alarming!!!!!! • RSV is the most important cause of LRT illness in infants and young children. • It is the main cause of: • Bronhiolitis (about 50%) • Pneumonia (25%) under one year of age.

25. Pathogenesis of Respiratory syncytial virus Involvement of the: immune response in the pathogenesis of some RSV respiratory symptoms especially bronchiolitis has been the subject for much speculation.

26. Laboratory diagnosis of parainfluenza & RSV s 1. Detection of viral antigen & \ or viral nucleic acid: Antigen detection: • Clinical specimens (exfoliated nasopharyngeal cells, nasopharyngeal secretions, aspirates or washes) by: • IF or ELISA techniques - N.A detection from the same specimens could be done using PCR

27. Laboratory diagnosis of respiratory tract infections (parainfluenza & RSV ) 2. Isolation & identification of the virus : The virus grow readily on T.C.C. identification is by: - the C.P.E; - I.F ( to detected V.AG.) & - or PCR (to detect V.N.A.) . In parainfluenza viruses: haemadsorption & haemagglutination may be used for specific identification.

28. Laboratory diagnosis of respiratory tract infections parainfluenza & RSV 3. Serology : Virus specific IgA are protective but disappear within few months.

29. Treatment of parainfluenza & RSV infection • Treatment is mainly symptomatic and include neubulized cold or hot steam with careful monitoring of the upper airway. • Ribavirin delivered in the form of small particle aerosal may be effective in life threatening infections.

30. Immunity to Parainfluenza & RSVs • It is apparent that serum neutralizing antibodies are only partially protective. • Reinfections are common and can occur in presence of viral antibodies but the severity of the disease is lowered.