microbiology 2 respiratory

What are the main viral causes of respiratory tract infections?

Myxoviridae, Coronaviridae, Picornaviridae, Adenoviridae.

Which viruses belong to the Orthomyxoviridae group?

Influenza viruses A, B, C, and D.

Which viruses belong to the Paramyxoviridae family?

Parainfluenza, mumps, measles, respiratory syncytial virus, human metapneumovirus.

Which family includes coronavirus?

Coronaviridae.

Which family includes human rhinoviruses?

Picornaviridae.

Which family includes adenovirus?

Adenoviridae.

What type of genome does Orthomyxoviridae have?

Segmented negative-sense RNA.

What type of genome does Paramyxoviridae have?

Non-segmented negative-sense RNA.

Where does Orthomyxoviridae replicate?

Nucleus.

Where does Paramyxoviridae replicate?

Cytoplasm.

What is the particle size of Orthomyxoviridae?

80–120 nm, highly pleomorphic.

What is the particle size of Paramyxoviridae?

125–250 nm, somewhat pleomorphic.

Which virus family includes influenza viruses?

Myxoviridae.

Which influenza viruses infect humans?

Influenza A, B, and C.

What is the shape of influenza virus particles?

Highly pleomorphic.

What type of envelope does influenza virus have?

Lipid envelope.

Which glycoprotein spikes project from the influenza envelope?

Haemagglutinin (HA) and Neuraminidase (NA).

What is the function of haemagglutinin (HA)?

Binds to sialic acid receptors on host cells.

What is the cellular receptor for influenza virus?

Sialic acid (N-acetyl neuraminic acid).

What is the function of neuraminidase (NA)?

Cleaves sialic acid to facilitate viral release.

What is the function of M2 protein?

Ion channel required for efficient viral replication.

Which protein lines the inner side of the influenza envelope?

Matrix protein M1.

How many RNA segments does influenza A and B have?

Eight segments.

How many RNA segments does influenza C have?

Seven segments.

What is the reservoir of influenza virus?

Acute infection in other humans.

How is influenza transmitted?

Aerial droplets inhaled into pharynx or lower respiratory tract.

What is the incubation period of influenza?

1–3 days.

Why does influenza spread rapidly?

Short incubation period and airborne transmission.

What does rapid spread of influenza lead to?

Epidemics.

How are influenza viruses classified into A, B, C, and D?

Based on antigenicity of nucleoprotein and M1 protein.

How are influenza subtypes classified?

According to HA and NA antigens.

How many HA subtypes exist?

18.

How many NA subtypes exist?

11.

What are the common clinical features of influenza?

Fever, myalgia, headache, and pharyngitis.

What respiratory symptom may accompany influenza?

Cough.

What severe symptom may occur in influenza?

Prostration.

Is coryza common in influenza?

No.

Which infection is characterized by coryza?

Common cold.

How severe can influenza infection be?

Mild, asymptomatic, moderate, or very severe.

Who are most prone to influenza complications?

Young children, elderly, and patients with chronic cardiopulmonary diseases.

What is the most serious complication of influenza?

Pneumonia.

Which bacteria commonly cause secondary pneumonia in influenza?

Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae.

Which viruses can cause superinfection with influenza?

Adenovirus.

What specimens are used for viral isolation of influenza?

Respiratory secretions (aspirate, gargle, nasal wash).

Which rapid test is used for influenza diagnosis?

Immunofluorescence (IF).

How is influenza virus isolated in the lab?

Cell culture or embryonated eggs.

Which serological test detects influenza antibodies?

Haemagglutination inhibition test.

Which molecular technique is used to diagnose influenza?

RT-PCR.

Which drugs inhibit influenza A virus uncoating?

Amantadine and Rimantadine.

Are amantadine and rimantadine effective against influenza B?

No.

Are amantadine and rimantadine effective against avian or swine flu?

No.

Which drugs inhibit neuraminidase?

Zanamivir and Oseltamivir.

Which influenza types are affected by neuraminidase inhibitors?

Influenza A and B.

Are neuraminidase inhibitors effective against avian and swine flu?

Yes.

What is the mechanism of action of oseltamivir?

Inhibits neuraminidase preventing viral release.

What type of influenza vaccine is formalin-inactivated?

Killed whole virus vaccine.

How is inactivated influenza vaccine produced?

Growth in embryonated eggs followed by purification and formalin inactivation.

How is inactivated influenza vaccine administered in adults?

Single intramuscular dose.

How is inactivated influenza vaccine given to children?

Two doses 4 weeks apart depending on age.

What other influenza vaccines exist besides inactivated vaccine?

Subunit vaccines and live attenuated vaccines (LAV).

What is antigenic shift?

Major change in HA and/or NA antigens.

How does antigenic shift occur?

Coinfection of a cell with two genetically different influenza viruses.

How often does antigenic shift occur?

Every 10–20 years.

Does antigenic shift involve a change in subtype?

Yes.

What is antigenic drift?

Minor antigenic changes in HA and NA.

How often does antigenic drift occur?

Yearly.

Does antigenic drift change the viral subtype?

No.

What is avian influenza?

Infectious disease of birds caused by influenza A viruses.

Which avian influenza strains are highly pathogenic?

H5 and H7 subtypes.

What characterizes highly pathogenic avian influenza in birds?

Sudden onset, severe illness, rapid death.

What is the mortality rate of highly pathogenic avian influenza in birds?

Can approach 100%.

Which avian influenza strain infected humans in Hong Kong in 1997?

H5N1.

How is avian influenza transmitted to humans?

From birds to humans.

Is human-to-human transmission of avian influenza documented?

No.

Which avian influenza strain appeared in China causing human infection?

H7N9.

Which avian influenza strains reemerged in 2020?

H5N1 in China and H5N8 in Saudi Arabia.

What is swine flu?

Influenza infection originating from pigs.

Why are pigs called mixing pots for influenza?

They can be infected by avian and human strains.

Which swine flu strain caused the 2009 pandemic?

H1N1.

Which swine flu strain appeared in 2011?

H3N2.

Is H1N1 included in seasonal influenza vaccine?

Yes.

What are the clinical symptoms of swine flu?

High fever, cough, sore throat.

What gastrointestinal symptoms may occur in swine flu?

Diarrhea and vomiting.

What severe complication may occur in swine flu?

Rapid progression to severe pneumonia.

What is the probable diagnosis in a patient with fever, dry cough, and ground-glass opacities?

Viral pneumonia due to influenza.

Which variant causes avian influenza in humans?

H5N1.