TREATMENT OF VIRAL RESPIRATORY INFECTIONS

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TREATMENT OF VIRAL RESPIRATORYINFECTIONS

• Erik DE CLERCQ
• Rega Institute for Medical Research,
  K.U.LeuvenB-3000 Leuven, Belgium

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RESPIRATORY TRACT VIRUS INFECTIONS

• ADENOVIRIDAE Adenoviruses
• HERPESVIRIDAE Cytomegalovirus,
  Varicella-zoster virus
• PICORNAVIRIDAE Enteroviruses (Coxsackie
  B, ECHO) Rhinoviruses
• CORONAVIRIDAE Coronaviruses
• ORTHOMYXOVIRIDAE Influenza (A, B, C) viruses
• PARAMYXOVIRIDAE Parainfluenza viruses
  Respiratory syncytial virus
  SARS (Severe Acute Respiratory
  Disease) virus

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RESPIRATORY TRACT VIRAL DISEASES

• Adenoviruses Adenoiditis, Pharyngitis,
  Bronchopneumonitis
• Cytomegalovirus Interstitial pneumonitis
• Varicella-zoster virus Pneumonitis
• Enteroviruses (Coxsackie B, ECHO) URTI (Upper
  Respiratory Tract Infections)
• Rhinoviruses Common cold
• Coronaviruses Common cold
• Influenza viruses Influenza (upper and lower
  respiratory tract infections)
• Parainfluenza viruses Parainfluenza (laryngitis,
  tracheitis)
• Respiratory syncytial virus Bronchopneumonitis

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INFLUENZA VIRUS
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Influenza virus
Electron micrographs of purified influenza
virions. Hemagglutinin (HA ) and neuraminidase
(NA) can be seen on the envelope of viral
particles. Ribonucleoproteins (RNPs) are located
inside the virions.
http//www.virology.net/Big_Virology/BVRNAortho.ht
ml
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Influenza
Layne et al., Science 293 1729 (2001)
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NA (neuraminidase)
Lipid bilayer
M1 (membrane protein)
M2 (ion channel)
RNPs (RNA, NP)
Transcriptase complex (PB1, PB2 and PA)
HA (hemagglutinin)
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Simplified representation of the influenza virion
showing the neuraminidase (NA) glycoprotein, the
hemagglutinin (HA) glycoprotein and the matrix
M2 protein
M2
McClellan and Perry, Drugs 61 263-283 (2001)
9
Distribution of influenza A hemagglutinin (H)
subtypes in nature
Figure adapted from Murphy Webster.
Orthomyxoviruses.
http//www.brown.edu/Courses/Bio_160/Projects1999/
flu/mechanism.html
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Distribution of influenza A hemagglutinins in
nature
http//www.brown.edu/Courses/Bio_160/Projects1999/
flu/mechanism.html
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Distribution of influenza A neuraminidases in
nature
http//www.brown.edu/Courses/Bio_160/Projects1999/
flu/mechanism.html
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Amantadine/rimantadine mechanism of action
limited to influenza A viruses
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Amantadine Symmetrel
14
Rimantadine Flumadine
15
The tetrameric M2 helix bundle
Sansom Kerr, Protein Eng. 6 65-74 (1993)
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Neuraminidase (NA)
Cleaves sialic acid from cell-surface glycoprotein
Glycoproteins and neuraminidase
Sialic acid
?
Sialic acid
?2,3
Galactose
Galactose
?1,4
N-acetyl-glucosamine
N-acetyl-glucosamine
Core sugars
Core sugars
protein
protein
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Influenza virus neuraminidase

• Functions
• removes terminal sialic acid residues
• promotes release of virus particles from the
  cells
• destroys cellular receptors recognized by
  hemagglutinin
• prevents virus aggregation at the cell surface
• prevents viral inactivation by respiratory mucus

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NEURAMINIDASE INHIBITORS

• GG167
• 4-Guanidino-Neu5Ac2en
• Zanamivir
• Relenza

• GS4104, Ro64-0796
• Ethyl ester of GS4071
• Oseltamivir
• Tamiflu

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Sialic acid N-Acetylneuraminic acid (NANA)
20
Sialyl ?-glycoside R glycoprotein
Transition state
Abdel-Magid et al., Curr. Opin. Drug Discov. Dev.
4 776-791 (2001)
21
H2O
R-O-
R-OH
Sialic acid
Transition state
Abdel-Magid et al., Curr. Opin. Drug Discov. Dev.
4 776-791 (2001)
22
DANA
Abdel-Magid et al., Curr. Opin. Drug Discov. Dev.
4 776-791 (2001)
23
FANA
Abdel-Magid et al., Curr. Opin. Drug Discov. Dev.
4 776-791 (2001)
24
Zanamivir Relenza
25
Oseltamivir phosphate Tamiflu
26
Oseltamivir GS4104 oral prodrug (ethyl
ester) form of GS4071
GS4071
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GS4071 bound to influenza neuraminidase
Kim et al., J. Am. Chem. Soc. 119 681-690 (1997)
28
GS4071 bound to influenza neuraminidase
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Zanamivir (Relenza)

• active against both influenza A and B
• IC50 0.21-2.6 ng/ml for influenza neuraminidase
• efficacy demonstrated in mouse and ferret models
  for influenza (upon topical administration)
• has to be administered by inhalation 10 mg bid
• therapeutically effective (5 days) significant
  reduction in duration of illness
• prophylactically effective (4 weeks)
  significant reduction in number of ill subjects
• well tolerated clinical adverse events not
  different from placebo
• no evidence for emergence of drug-resistant virus

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Oseltamivir (Tamiflu)

• active against both influenza A and B
• IC50 lt 1 ng/ml for influenza neuraminidase
• efficacy demonstrated in mouse and ferret models
  for influenza (upon oral administration)
• can be administered orally 75 or 150 mg bid
• therapeutically effective (5 days) significant
  reduction in duration of illness
• prophylactically effective (6 weeks)
  significant reduction in number of ill subjects
• well tolerated clinical adverse events not
  different from placebo
• no evidence for emergence of drug-resistant virus

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RESISTANCE MUTATIONS TO NEURAMINIDASE INHIBITORS

• Neuraminidase
• 119 Glu ? Gly
• specific for zanamivir
• Glu 119 interacts with guanidinium group of
  zanamivir
• 292 Arg ? Lys
• found for zanamivir cross-resistance to
  oseltamivir
• Arg 292 interacts with carboxylic acid group of
  zanamivir and oseltamivir
• Hemagglutinin
• Some mutations (i.e. 198 Thr ? Ile) diminish
  affinity of hemagglutinin for its receptor

McKimm-Breschkin, Antiviral Res. 47 1-17 (2000)
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Benefits offered by neuraminidase inhibitors

• Therapeutically
• Reduction in illness duration by 1-2 days
• Reduction in risk-virus transmission to household
  or healthcare contacts
• Reduction in complications (sinusitis,
  bronchitis)
• Reduction in use of antibiotics
• Prophylactically
• Seasonal prevention of infection

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RWJ-270201
Smee et al., Antimicrob. Agents Chemother. 45
743-748 (2001) Sidwell et al., Antimicrob. Agents
Chemother. 45 749-757 (2001)
34
A-192558
Wang et al., J. Med. Chem. 44 1192-1201 (2001)
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A-315675
DeGoey et al., J. Org. Chem. 67 5445-5453
(2002) Hanessian et al., J. Am. Chem. Soc. 124
4716-4721 (2002)
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T-705
T-705 showed potent inhibitory activity against
influenza A, B, and C viruses, with 50
effective inhibitory concentrations of 0.013 to
0.48 µg/ml, while it showed no cytotoxicity at
concentrations up to 1,000 µg/ml. T-705 was also
active against a neuraminidase
inhibitor-resistant virus and amantadine-resistant
viruses.
Furuta et al., Antimicrob. Agents Chemother. 46
977-981 (2002)
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HUMAN RHINOVIRUS (HRV)
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HRV 14 Human rhinovirus type 14
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Antirhinoviral targets for therapy
Agents can (a) prevent viral attachment to
host-cell receptors (ICAM-1 and the low density
lipoprotein receptor), (b) inhibit viral
uncoating or (c) inhibit viral protein synthesis
by blocking 3C viral protease.
McKinlay, Curr. Opin. Pharmacol. 1 477-481 (2001)
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Phenoxyalkyldiketone Arildone WIN38020
De Clercq, In Antiviral Agents and Human Viral
Diseases. Galasso, Whitley Merigan, eds.
Lippincott-Raven Publishers, pp 1-44 (1997)
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Isoxazole Disoxaril WIN 51711
De Clercq, In Antiviral Agents and Human Viral
Diseases. Galasso, Whitley Merigan, eds.
Lippincott-Raven Publishers, pp 1-44 (1997)
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Pyridazinamine R61837
De Clercq, In Antiviral Agents and Human Viral
Diseases. Galasso, Whitley Merigan, eds.
Lippincott-Raven Publishers, pp 1-44 (1997)
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Phenoxypyridazinamine Pirodavir R77975
De Clercq, In Antiviral Agents and Human Viral
Diseases. Galasso, Whitley Merigan, eds.
Lippincott-Raven Publishers, pp 1-44 (1997)
44
Interaction of WIN 52035 with VP1 of human
rhinovirus (HRV-14)
Andries, In Antiviral Chemotherapy. Jeffries
De Clercq, eds. John Wiley Sons, Chichester, pp
287-319 (1995)
45
Interaction of R61837 with VP1 of human
rhinovirus (HRV-14)
Andries, In Antiviral Chemotherapy. Jeffries
De Clercq, eds. John Wiley Sons, Chichester, pp
287-319 (1995)
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Pleconaril (VP-63843)
Romero, Exp. Opin. Invest. Drugs 10 369-379
(2001)
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BTA188
BTA showed potent in vitro activity against 87 of
100 rhinovirus serotypes with a median EC50 of 10
ng/ml, superior to pleconaril. BTA188 is targeted
at the hydrophobic pocket in the core of VP1.
Hayden et al., Antiviral Res. 50 A127 (2001)
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Benzothiazole
Benzothiazole targeted at hydrophobic pocket in
the core of VP1. EC50 against HRV-14 in cell
culture 0.8 µM.
Tsang et al., Chem. Biol. 8 33-45 (2001)
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Ruprintrivir
Inhibitor of human rhinovirus C3 protease,
currently undergoing clinical evaluation for the
prevention and treatment of the common cold.
Hsyu et al., Antimicrob. Agents Chemother. 46
392-397 (2002)
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Pyridone
Human rhinovirus (HRV) 3C protease inhibitor
showed an average EC50 of 45 nM across 15
serotypes of HRV.
Dragovich et al., J. Med. Chem. 45 1607-1623
(2002)
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RESPIRATORY SYNCYTIAL VIRUS (RSV)
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Respiratory Syncytial Virus (RSV) and
Parainfluenza Virus (PIV)
Hall, N. Engl. J. Med. 344 1917-1928 (2001)
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Characteristics of the proteins of respiratory
syncytial virus and parainfluenza virus
Protein Molecular mass Molecular mass Functions
Respiratory syncytial virus Parainfluenza virus
kilodaltons kilodaltons
Structural protein
Surface
Fusion (F) 68 60 Penetration major protection antigen
Attachment (G) 90 a Viral attachment major protective antigen
Hemagglutinin neuraminidase (HN) a 69 Viral attachment and release major protective antigen
Small hydrophobic (SH 1A) 4.8 30b a Unknown
Matrix
Matrix (M) 28 22b 40 a Mediates attachment of nucleocapsid to envelope
Small envelope (M2) Transcriptional regulation unique to pneumoviruses
Nucleocapsid-associated
Nucleoprotein (N, NP) 44 58 Major RNA-binding nucleocapsid protein
Phosphoprotein (P) 37 60 Major phosphorylated protein RNA-dependent RNA polymerase activity
Large polymerase complex (L) 200 250 Large nucleocapsid-associated protein major polymerase subunit RNA-dependent RNA polymerase activity
aNot present in the virus. bThere are four glycosylated and nonglycosylated forms with molecular masses of 4.8, 7.5, 13 to 15, and 21 to 30 kd. aNot present in the virus. bThere are four glycosylated and nonglycosylated forms with molecular masses of 4.8, 7.5, 13 to 15, and 21 to 30 kd. aNot present in the virus. bThere are four glycosylated and nonglycosylated forms with molecular masses of 4.8, 7.5, 13 to 15, and 21 to 30 kd. aNot present in the virus. bThere are four glycosylated and nonglycosylated forms with molecular masses of 4.8, 7.5, 13 to 15, and 21 to 30 kd.
Hall, N. Engl. J. Med. 344 1917-1928 (2001)
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Epidemiologic pattern of infections with
respiratory syncytial virus in relation to the
occurrence of bronchiolitis from 1993 through 1998
Hall, N. Engl. J. Med. 344 1917-1928 (2001)
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Proportion of samples taken from cases of
influenza-like illness positive for influenza or
respiratory syncytial virus in 0-5-year-olds
during 1996-1997
Zambon et al., Lancet 358 1410-1416 (2001)
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Proportion of samples taken from cases of
influenza-like illness positive for influenza or
respiratory syncytial virus in 0-5-year-olds
during 1996-1997
Zambon et al., Lancet 358 1410-1416 (2001)
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Ribavirin Virazole
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RFI-641
RFI-641 inhibits RSV fusion mediated by F
(Fusion) protein, but also interferes with the
attachment (G) protein
Nikitenko et al., Bioorg. Med. Chem. Lett. 11
1041-1044 (2001) Razinkov et al., Chem. Biol. 8
645-659 (2001)
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Morphology of CV-1 cells treated with RFI-641

• Noninfected, nontreated CV-1 cells (B)
  RSV-infected, untreated
• CV-1 cells (C) RSV-infected, RFI-641 (gt 8
  h)-treated CV-1 cells

Huntley et al., Antimicrob. Agents Chemother. 46
841-847 (2002)
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Therapeutic efficacy of RFI-641 after intranasal
administration to RSV-infected African green
monkeys
RFI-164 was administered intranasally, daily,
starting 1 day after virus infection
Huntley et al., Antimicrob. Agents Chemother. 46
841-847 (2002)
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R-170591 interferes with RSV fusion
Andries et al., 40th ICAAC, Toronto, Canada,
17-20 September 2000, Abstract H-1160
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Benzodithiin (RD3-0028)
RD3-0028 inhibits RSV replication by interfering
with intracellular processing of the RSV fusion
protein, leading to loss of infectivity
Sudo et al., Microbiol. Immunol. 45 531-537
(2001)
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• PARAMYXOVIRIDAE
• Paramyxovirinae
• Respirovirus/Paramyxovirus (Sendai virus,
  Parainfluenza 1 and 3)
• Rubulavirus (Mumps virus, Parainfluenza 2, 4a
  and 4b)
• Morbillivirus (Measles virus)
• Megamyxovirus (Hendra and Nipah virus)
• Pneumovirinae
• Pneumovirus (Pneumovirus, Respiratory Syncytial
  Virus)
• Metapneumovirus (Human metapneumovirus)

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(No Transcript)
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OUTBREAK-INSPIRED HUNT FOR VIRUSES

• Hendra virus (1994, Megamyxovirus)
• Australian bat lyssavirus (1996, Rhabdoviridae)
• Menangle virus (1997, Rubulavirus)
• Tupaia virus (1999, Paramyxovirus)

• Nipah virus (1999,
  Megamyxovirus)
• Tioman virus (2000,
  Rubulavirus)
• Dolphin, porpoise and cetacean morbillivirus
  (1991, Morbillivirus)
• Salem virus (2000, not yet classified)

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DIFFERENCES BETWEEN
HENDRA NIPAH VIRUS
OTHER PARAMYXOVIRINAE

• Multiple host species
• Reservoir host
• fruit bats (flying foxes) ?
• Clinical hosts
• horse, pig, man,...
• Experimental hosts
• guinea pig, cat
• Not very contagious
• No human-to-human spread, but infection is very
  lethal

Host specific human and Highly
contagious Human-to-human spread,
droplet infection
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CONCLUSIONAPPROVED ANTIVIRAL DRUGS FOR THE
TREATMENT OF THE MAJOR RESPIRATORY TRACT VIRUS
INFECTIONS

• Adenoviruses none
• PicornavirusesEntero
  noneRhino
  none
• OrthomyxovirusesInfluenza
  Neuraminidase inhibitors
  
  zanamivir, oseltamivir
• 
  Amantadine and rimantadine (for
  influenza A only)
• ParamyxovirusesParainfluenza
  noneRespiratory syncytial virus
  RibavirinSARS virus
  none