Vinnitsa National Pirogov Memorial Medical University / Department of microbiology

Viruses causing respiratory infections. Influenza viruses.

Paramyxoviruses. Measles and mumps viruses.

Classification of an Orthomyxoviridae

Family Orthomyxoviridae includes three pathogenic for human species:

Influenza virus AInfluenza virus BInfluenza virus C

Influenza virus

Antigenic structure of influenza virusInternal 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 virusAntigenic variability may be of two

different types:

1.Antigenic drift

2.Antigenic shift

Epidemiology of the fluThe source of infection may be:

1.Infected person

2.Wild and domestic birds

3.Domestic animalsCharacteristics of the viruses have caused the most

famous pandemics:In 1917-1919 “Spanish flu” was caused by A (H1N1)

virusIn 1957 “Asian flu” was caused by A (H2N2) virusIn 1968 “Hong Kong flu” was caused by A/Hong Kong

(H3N2)In 1977 “Red flu” was caused by A (H1N1)From 1968 and 1977 pandemics both types (H1N1 and

H3N2) have been circulated together

1.

Endemic influenza annually in the US1

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 fluAvian Influenza, cumulative data2

379 cases reported, 239 deaths (63%) 2008: 28 cases / 22 deaths

1http://www.cdc.gov/flu/keyfacts.htm2APR 08, WHO

Avian Influenza, cumulative data2

379 cases reported, 239 deaths (63%) 2008: 28 cases / 22 deaths

Laboratory diagnosticsCollected samples are nasal or throat swabs, nasal or

throat washing, sputum, nasal printsRapid 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 diagnosticsMicroscopy

Isolation of the virus (culture or virological method)

Serology (serological method)

Laboratory diagnostics of the fluImmunofluorescence Virus inoculation into chicken

embryo

Specific prophylaxisSpecific prophylaxis is immunization with subunit

influenza vaccines 3-4 weeks before predictable onset of epidemic (Fluarix, Influvac, Vaxigrippe, Grippol and others).

ParamyxovirusesFamily ParamyxoviridaeSubfamily 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 pathogenesityParainfluenza 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 50-80% 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 diagnostics1. 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 diagnostics1. 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 virusType 1 and type 2 cause croup ( acute

laryngotracheobronchitis) in childrenType 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