MYCO - Orthomyxoviridae

Orthomyxoviridae

• ssRNA, enveloped, helical

• 3 major antigenic types: A,B,C

• MATRIX protein (M) AND Nucleoprotein (NP)

• Types A & B cause nearly all human disease

Influenza A

• 8 segments

• MOT: contact with respiratory secretions

• DISEASE AND DIAGNOSIS:

  • Influenza (fever,malaise,headache,myalgia,cough)

  • PRIMARY INFLUENZA PNEUMONIA

  children:

  bronchiolitis,croup,otitis media

DIAGNOSIS: cell culture(PMK,MDCK). EIA,FA stain,RT-PCR,rapid test kit

TREATMENT: SUPPORTIVE,

antivirals:

amantadine rimantadine (for influenza A) oseltamivir

Neuraminidase inhibitors for Influenza A & B)

PREVENTION: influenza vaccine or antiviral prophylaxis

Influenza B

• 8 segments

• MOT: contact with respiratory secretions

• DISEASE: mild influenza

• TREATMENT: SUPPORTIVE,

  antivirals: zanamivir oseltamivir
  PREVENTION: influenza vaccine or antiviral prophylaxis

Influenza C

• 7 segments

• MOT: contact with respiratory secretions

• seasonal flu - mild form of influenza causing URTIs

  DIAGNOSIS:

• testing is not routinely requested, the virus is infrequently detected: only valid test NAAT

hemagglutination

• (H1-H16)

• adsorption and attachment

Neuraminidase

• (N1-N9)

• penetration and budding

antigen variation

1. antigenic drift

2. antigenic shift

3. strains

antigenic drift

• minor change in antigenic structure

• occurs in point mutations in the viral genes encoding the HA & NA spikes. It can also occur within any of three influenza viruses and may cause Local (epidemics) INFLUENZA OUTBREAK

antigenic shift

• drastic change in antigenic structure

• RESULTS to new H and N antigens. may cause (epidemics) and epidemic and pandemics (occurs to Influenza A only)

mechanisms of antigenic shift

1. genetic reassortment

2. adaptive mutation

genetic reassortment

genomes of different influenza viruses combine into single virion, resulting new strain of influenza virus

adaptive mutation

novel virus slowly adjusts and becomes transmissible form mammalian (including human) host

Strains

1. H1N1 - spanish flu, swine flu, bird flu (1918-1919)

2. H2N2 - asian flu (1957-1958)

3. H3N2 - hongkong flu (1968)

4. H5N1 - avian flu (HPAI) highly pathogenic avian influenza

5. H7N9 - novel avian flu (china) *predominant strain

H1N1

spanish flu, swine flu, bird flu (1918-1919)

H2N2

asian flu (1957-1958)

H3N2

hongkong flu (1968)

H5N1

avian flu (HPAI) highly pathogenic avian influenza

H7N9

novel avian flu (china) *predominant strain

rna segments

A- 8 segments

B- 8 segments

C - 7 segments

antigenic drift

A- +

B- +

C-+

antigenic shift

A- +

B- (-)

C- (-)

hemagglutination

A- +

B- +

C- +

neuraminidase

A- +

B-+

C- (-)

Paramyxoviridae

ssRNA, enveloped, helical with no segment genome

measles rubeola

• kopliks spots (buccal cavity)

• MOT: Contact with respiratory

  secretions; extremely contagious

  titer of ab: low

DISEASE

• measles atypical measles (occurs in waning vaccine immunity)

• subacutesclerosing panencephalitis

DIAGNOSIS:

cell culture (PMK) and serology

TREATMENT:

Supportive; immunocompromised patients can be treated with immune serum globulin

PREVENTION: measles vaccine

mumps virus

• MOT: person-to-person-contact

  respiratory droplet infected saliva

DISEASE:

mumps (unilateral/bilateral) swelling of the glands; other glands (testes, ovaries and pancreas)

TREATMENT:

supportive

Prevention: mumps vaccine

PIV-14 (parainfluenza virus)

• PIV 1 (more often)

• PIV 1-2 - (serious disease in children)

• MOT: contact with respiratory secretions

DISEASE: adults:supper respiratory disease, rarely pneumonia

children: respiratory including croup (laryotracheobronchitis) bronchiolitis and pneumonia

DIAGNOSIS:

cell culture (PMK), shell vial culture, IF stain (rapid)

TREATMENT:

supportive; aerolized ribavirin

PREVENTION:

avoid contact with virus

virulence factors

• hemagglutination - neuraminidase (HN) - viral adhesion molecule

• Fusion (f) antigen - fusion of virus to the cell and one infected cell to another infected cell

1. RSV (Respiratory Syncytial Virus

   MOT: Person to person by hand and respiratory contact (large particle droplet)

   DISEASE:

   • Primarily in infants and children.

   • Infants: bronchiolitis,pneumonia and croup

   • Children: upper respiratory disease

Diagnosis: Cell culture, (Hep-2), EIA and FA stain

TREATMENT:

supportive; treat severe disease compromised infects

with ribavirin; MAB palivizumab (blocks RSV entry into the host cell)

PREVENTION:

Avoid contact with viruses; immune globulin for infants with underlying lung disease

2. Human metapnemovirus (HMPV)

MOT: Person-to person

DISEASE: Primarily in infants and children;

bronchiolitis and pneumonia

DIAGNOSIS:

RT-PCR

EPIDEMIOLOGY:

winter epidemics varies year to year

TREATMENT:

Supportive

PREVNTION:

Avoid contact with virus

RSV (Respiratory Syncytial Virus)

MOT: Person to person by hand and respiratory contact (large particle droplet)

DISEASE:

• Primarily in infants and children.

• Infants: bronchiolitis,pneumonia and croup

• Children: upper respiratory disease

Diagnosis: Cell culture, (Hep-2), EIA and FA stain

Human metapnemovirus (HMPV)

MOT: Person-to person

DISEASE: Primarily in infants and children;

bronchiolitis and pneumonia

DIAGNOSIS:

RT-PCR

EPIDEMIOLOGY:

winter epidemics varies year to year

F protein

causes infected cells to fuse form of syncytia

Picornaviridae

• ssRNA,naked,icosahedral (largest)

  VIRUS AND CHARCATERISTICS

  • enteroviruses 73 to 120

  • rhinoviruses A to C

  • polioviruses 1 to 3

  • coxsackieviruses A1 to A24

  • coxsackieviruses B1 to B6

  • echoviruses l to 33

MOT: Fecal-oral - route ( polio)

aerosol and inahalation fomites ( coxsackieviruse A & B, Enterovirus and echinovirus)

enteroviruses

73 to 120

rhinoviruses

A to C

polioviruses

1 to 3

coxsackieviruses

• A1 to A24

• B1 to B6

echinovirus

1 to 33 / l to 33

diseases of picornaviridae

• poliovirus: polio

• Coxsackie A: herpangina, HFMD ( Hand-foot - mouth - disease)

• Coxsackie B: pleurodynia,pericarditis,myocarditis

• Echovirus: congenital and neonatal disease,myocarditis/pericarditis,febrile illness with ras,meningitis

• Enterovirus 70: conjunctivitis

TREATMENT:

supportive,pleconaril

PREVENTION:

Avoid contact with viruses, vaccination for polio

HEPA A VIRUS (enterovirus type 72)

• MOT: fecal oral route

• DISEASE:

  Hepatitis with short incubation, abrupt onset, low mortality, no carrier state

  HEPATITIS B (long incubation carrier state)

• DIAGNOSIS: serology

• TREATMENT: supportive

• PREVENTION: Vaccine; prevent clinical

  illness with serum immunoglobulin

rhinovirus

• 150 serotypes

• common cold

• labile (nose) vs entero-stable(mouth)

  -aseptic - causes aspetic meningitis

  meningitis - summer flu (+)

  - summer flu (-)

• MOT: aerosols, contact with secretions and fomites

• DISEASE: common cold

• DIAGNOSIS: cell culture not necessary

  RT-PCR

• TREATMENT: supportive

• PREVENTION: Avoid contact with

  viruses

Reoviridae

• dsRNA, naked, icosahedral

• MOT:fecal-oral route,foodborne,waterborne

• DISEASE: gastroenteritis in infants and young children