Swine-Origin Influenza Virus (A/H1N1)(A/H1N1)

Chuan-Liang Kao

Department of Laboratory Medicine, NTUHDepartment of Clinical Laboratory Science andDepartment of Clinical Laboratory Science and

Medical Biotechnology,National Taiwan UniversityNational Taiwan University

IntroductionFamily: Orthomyxoviridae

Genus Type speciesInfluenzavirus A Influenza A virusInfluenzavirus B Influenza B virusInfluenzavirus C Influenza C virusInfluenzavirus C Influenza C virus

A/Brisbian/07/2007(H1N1) A/Swine/Wisconsin/238/97(H1N1)

HemagglutininNeuraminidase

Influenza virus

• Orthomyxoviridae, Enveloped , segmented ti RNAnegative-sense RNA

Medical microbiology

Hemagglutinin & Neuraminidase Subtypes of Influenza A Virus

humans swine birds horses

Humans swine birds horsesN1 + + +

humans swine birds horsesH1 + + +H2 + +H3 + + + +

N2 + + +N3 + +N4

H4 +H5 + + H6 + H7 + + + N4 +

N5 + N6 +

H7 + + + H8 +H9 + +H10 + N6 +

N7 + + + N8 + +

H11 +H12 +H13 +H14 + N9 +H14 +H15 +H16 +

Antigenic shift

( Yen, 2004, CDC, Taiwan)

Horimoto et al. Clinical Microbio Rev 2001; 41:129–149

GISAID sequence database

GISAID sequence database 2009GISAID sequence database 2009

Olsen CW. 2002

Olsen CW. 2002

Since 1999

Choi YK et al.Arch Virol (2002) 147: 1209–1220

SwineSwine--Origin Influenza A H1N1 (SOrigin Influenza A H1N1 (S--OIV)OIV)Drug Susceptibility

13 (20%) of 64 patients have been13 (20%) of 64 patients have been tested for resistance to antiviral medicationsmedications.

To date, all tested viruses are resistant ,to amantadine and rimantadine but are susceptible to oseltamivir and zanamivir p

MMWR 2009;58:April 28.

Laboratory Diagnosis

Confirmed case of swine influenza A(H1N1) virus i f ti i d fi d i di id l

y g

infection is defined as an individualwith laboratory confirmed swine influenza A(H1N1) virus infection by one or more of the following tests:infection by one or more of the following tests:

• Real­time RT­PCR• Viral culture• Four­fold rise in swine influenza A(H1N1) virus

ifispecific neutralizing antibodies.

A Probable case of swine influenza A(H1N1) virus infection is defined as an individualwith an influenza test that is positive for influenza A, but is unsubtypable by reagents used to detect seasonal influenza virus infection ORinfluenza virus infection ORA individual with a clinically compatible illness or who died of an unexplained acute respiratory illness who is p p yconsidered to be epidemiologically linked to a probable or confirmed case.

Nucleic AcidNucleic AcidVirus Antigen

Specimen Collection for Influenza Virus Detection

Quick Vue Influenza for influenza virus antigen detection

Reliability and Interpretation of Rapid Influenza Test R ltResults

•The reliability of rapid influenza diagnostic tests depends largely on the y p g p g yconditions under which they are used, and are entirely based on the experiencewith seasonal influenza. •For detection of seasonal influenza virus infection, sensitivities of rapid diagnostic tests are approximately 50-70% when compared with viral culture or RT-PCR, and specificities of rapid diagnostic tests for influenza are approximately 90-95%. Sensitivity and specificity of these tests for detection of the novel H1N1 flu virus are unknown. •False-positive (and true-negative) results are more likely to occur when influenza is uncommon in the community, which is generally at the beginning

d d f tb kand end of an outbreak. •False-negative (and true-positive) results are more likely to occur when influenza is common in the community, which is typically at the height of an outbreakoutbreak. •Test sensitivity may vary depending on when in the course of illness the specimen is collected. Respiratory specimens for testing should be collected in the first 4 5 days of illness when viral shedding is greatestthe first 4-5 days of illness when viral shedding is greatest.

How to interpret a positive test result p p

•The patient might have novel H1N1 virus infectionThe patient might have novel H1N1 virus infection •The patient might have seasonal influenza A virus infection or•The patient might have a false positive test result.

R d d T t f I fl A/ HiN1 (S i )Recommended Tests for Influenza A/ HiN1 (Swine)

Real-time RT-PCR for influenza A, B

Inf A (+)Inf B (+)

S l i fSeasonal inf Real-time PCR for human H1, H3, Avian H5

Positive for Positive for N tiHuman H1or H3 Avian H5 Negative

Real-time RT-PCRf A/H1N1 fl ( i )Seasonal inf Avian flu for A/H1N1 flu (swine)

Positive Negative

A/H1N1 flu (swine)

Biosafety Guidelines for laboratory Workers April 24, 2009

Virus isolation : BLS2 plus or BSL3

Personal Precaution:1. Use personal protective equipment2. Respiratory protection : N95 or higher level3. Shoe covers4. Close-front gown5. Double gloves6. Eye protection (Goggles or face shields)

Appropriate disinfectants:

1. 70% Ethanol2. 5% Lysol3. 10% Bleach3. 10% Bleach