Viruses causing respiratory infections Influenza viruses Paramyxoviruses Measles

Viruses causing respiratory infections. Influenza viruses. Paramyxoviruses. Measles and mumps viruses. Vinnitsa National Pirogov Memorial Medical University / Department of microbiology

Classification of an Orthomyxoviridae Family Orthomyxoviridae includes three pathogenic for human species: Influenza virus A Influenza virus B Influenza virus C

Influenza virus

Antigenic structure of influenza virus Internal antigens (S-antigen) 1. Ribonucleoprotein (RNP) 2. M-protein from inner layer of envelope External antigens (V-antigen) 1. Hemagglutinin (HA) 2. Neuraminidase (N)

Antigenic variation of influenza virus Antigenic variability may be of two different types: 1. Antigenic drift 2. Antigenic shift

Epidemiology of the flu The source of infection may be: 1. Infected person 2. Wild and domestic birds 3. Domestic animals Characteristics of the viruses have caused the most famous pandemics: In 1917 -1919 “Spanish flu” was caused by A (H 1 N 1) virus In 1957 “Asian flu” was caused by A (H 2 N 2) virus In 1968 “Hong Kong flu” was caused by A/Hong Kong (H 3 N 2) In 1977 “Red flu” was caused by A (H 1 N 1) From 1968 and 1977 pandemics both types (H 1 N 1 and H 3 N 2) have been circulated together

Endemic influenza annually in the US 1 5% to 20% of the population gets the flu More than 200, 000 people are hospitalized from flu complications About 36, 000 people die from flu Avian Influenza, cumulative data 2 379 cases reported, 239 deaths (63%) 2008: 28 cases / 22 deaths 1 http: //www. cdc. gov/flu/keyfacts. htm 2 APR 08, WHO

Avian Influenza, cumulative data 2 379 cases reported, 239 deaths (63%) 2008: 28 cases / 22 deaths

Laboratory diagnostics Collected samples are nasal or throat swabs, nasal or throat washing, sputum, nasal prints Rapid tests are based on the demonstration of the virus antigens in the collected material. They include: 1. Direct immunofluorescence 2. Reversed indirect hemagglutination test (RIHA) 3. FLU OIA and QUICKVUE Influenza Test are based on detection of the viral antigens with monoclonal antibody 4. ZSTATFLU is based on detection of viral neuraminidase with colored substrate of the enzyme

Laboratory diagnostics Microscopy Isolation of the virus (culture or virological method) Serology (serological method)

Laboratory diagnostics of the flu Immunofluorescence Virus inoculation into chicken embryo

Specific prophylaxis is immunization with subunit influenza vaccines 3 -4 weeks before predictable onset of epidemic (Fluarix, Influvac, Vaxigrippe, Grippol and others).

Paramyxoviruses Family Paramyxoviridae Subfamily Paramyxovirinae includes three genera: Respirovirus (four serotypes of parainfluenza viruses) Morbillivirus (measles virus) Rubulavirus (mumps virus) Subfamily Pneumovirinae contains one genus Pneumovirus (respiratory syncytial virus)

Structure of a paramyxovirus

Antigenic structure and biological features Outer antigens: HN and F Inner antigens: RNP and M-protein

Epidemiology and pathogenesity Parainfluenza viruses cause croup (acute laryngotracheo-bronchitis), laryngitis, brochiolitis and pneumonia in children and a disease resembling the common cold in adults. They are responsible for 5080% of respiratory tract infections Measles virus causes measles Mumps virus causes mumps The source of infection is an ill person Paramyxoviruses are transmitted via respiratory droplets (airborne diseases)

Maculopapular rash (measles)

Laboratory diagnostics 1. Rapid tests: Immunofluorescence test Cytoscopy 2. Culture method 3. Serological investigation

Treatment and prophylaxis Prophylaxis is made by immunization with alive attenuated vaccine For current prophylaxis in pregnant women, children with immunodeficiency anti-measles and normal human immunoglobulin are used

Mumps: clinical findings and immunity Mumps is acute infectious disease commonly affecting children and characterized by nonsuppurative enlargement of parotid glands

Laboratory diagnostics 1. Virus isolation (culture method) 2. Serological tests Prevention of mumps may be done with alive attenuated vaccine Current prophylaxis is possible with either alone vaccine (active immunization) or normal human immunoglobulin (passive immunization)

Parainfluenza virus Type 1 and type 2 cause croup ( acute laryngotracheobronchitis) in children Type 3 cause tracheobronchitis, bronchiolitis and pneumonia in children before 5 years. Type 4 provokes mild respiratory infections Laboratory diagnosis is based on virus isolation from throat and nasal swabs. Serological tests with paired sera can confirm diagnosis by 4 -fold and greater rising of antibody titer