Published Date: 2005-10-15 23:50:00
Subject: PRO/AH/EDR> Influenza viruses, drug resistance (05)
Archive Number: 20051015.3014
INFLUENZA VIRUSES, DRUG RESISTANCE (05)
**************************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>
Date: Sat 15 Oct 2005
From: ProMED-mail <promed@promedmail.org>
Source: Nature online, Brief communications, Fri 14 Oct
2005 [edited]
<http://www.nature.com/nature/journal/vaop/ncurrent/pdf/4371108a.pdf>)
[Herewith is the text of the Brie Communications article
published in Nature (ahead of print) that was not accessible
at the time of posting of "Influenza viruses, drug
resistance (04) 20051015.2999". - Mod.CP]
Isolation of drug-resistant H5N1 virus
--------------------------------------
The persistence of H5N1 avian influenza viruses in many
Asian countries and their ability to cause fatal infections
in humans have raised serious concerns about a global flu
pandemic (1). Here we report the isolation of an H5N1 virus
from a Vietnamese girl that is resistant to the drug
oseltamivir (2), which is an inhibitor of the viral enzyme
neuraminidase and is currently used for protection against
and treatment of influenza. Further investigation is
necessaryto determine the prevalence of
oseltamivir-resistant H5N1 viruses among patients treated
with this drug.
An H5N1 influenza virus, A/Hanoi/30408/ 2005, was isolated
on 27 Feb 2005 from a 14 year old Vietnamese girl (patient
1) who had received a prophylactic dose (75mg once a day) of
oseltamivir from 24 to 27 Feb 2005 and was given a
therapeutic dose (75mg twice daily) for 7 days starting on
28 Feb. No virus was isolated from specimens after the
administration of increased doses of oseltamivir. The
patient recovered and was discharged from hospital on 14 Mar
2005.
Direct sequencing after amplification by polymerase chain
reaction of the virus isolated from a specimen collected on
27 Feb 2005 indicated that some of the virus population had
a histidine-to-tyrosine substitution at position 274
(represented as H274Y) in its neuraminidase protein, a
mutation that confers resistance to oseltamivir (3,4,5). We
therefore tested the sensitivity of the virus to oseltamivir
carboxylate (6) -- the active form of the drug -- and found
that the dose required for 50 per cent inhibition of
neuraminidase activity (IC50) in the isolate was 90 nM,
which exceeds the IC50 for oseltamivir-sensitive viruses
(0.1�10 nM ) (7). We then plaque-purified the virus.
Ten viral clones, randomly picked from the resultant
plaques, were classified into 3 groups according to their
response to oseltamivir (see supplementary information): 6
were highly resistant to the drug (IC50 = 763 nM), 3 were
slightly resistant (IC50 values between 7.1 and 12.5 nM) and
one was highly sensitive (IIC50 = 0.6 nM). The highly
resistant viruses had tyrosine at position 274 in their
neuraminidase, whereas those showing only slight resistance
had serine at position 294.
Patient 1 had not had any known direct contact with poultry,
but had cared for her 21 year old brother (patient 2) while
he had a documented H5N1 virus infection (for details of the
disease course and treatment in these patients, see
supplementary information). We found that the neuraminidase
gene of the brother�s virus was identical to clone 7 of
the girl�s virus (see supplementary information). Also,
the haemagglutinin gene of the brother�s virus was
identical to clones 2 and 9 of the girl�s virus, apart
from a nucleotide change at position 271. The timing of
infection in these 2 patients, together with the lack of
known interaction of the girl with poultry, raises the
possibility that the virus could have been transmitted from
brother to sister.
We assessed the growth of a highly oseltamivir-resistant
clone (H274Y,clone 9) and of an oseltamivir-sensitive clone
(H274, clone 7) in ferrets (8). Viral titres were higher in
animals infected with the oseltamivir-sensitive virus (See
figure in original text). Oseltamivir treatment reduced
viral titres in animals infected with the drug sensitive
virus (See original text for figure), but not in animals
infected with the resistant virus. However, all of the viral
clones, including those highly resistant to oseltamivir,
were sensitive to zanamivir (9, 10) (IC50 = 0.5�3.1 nM),
another neuraminidase inhibitor. In ferrets, we found that
zanamivir treatment reduced viral titres in animals infected
with virus that was oseltamivir-sensitive or
oseltamivir-resistant (see original figures).
We investigated how the viruses bound in vitro to different
configurations of sialyl glycopolymers, similar to those on
the host�s cell-surface receptor (11). We compared binding
by 2 of the viral clones (clones 7 and 9) with binding by an
avian flu virus (A/duck/Mongolia/ 301/2001) and another
human flu virus (A/Kawasaki/1/2001). We found that both H5N1
clones bound to -2,3-linked polymer and (less efficiently)
to -2,6-linked polymer (seeoriginal text figure). The
A/duck/Mongolia/301/2001 virus also bound -2,3-linked
polymer but did not bind -2,6- linked polymer at all; the
A/Kawasaki/1/2001 virus bound strongly to -2,6-linked
polymer but only weakly to -2,3-linked polymer (results not
shown). The broader binding properties of our H5N1 viral
clones may reflect a degree of adaptation in human hosts.
Although our findings are based on a virus from only a
single patient, they raise the possibility that it might be
useful to stockpile zanamivir as well as oseltamivir in the
event of an H5N1 influenza pandemic. They also highlight the
importance of monitoring the emergence of drug resistance in
H5N1 isolates from patients treated with neuraminidase
inhibitors.
[Authored by Q. Mai Le and 15 others, at the National
Institute of Hygiene and Epidemiology, Hanoi, Vietnam;
Division of Virology, Department of Microbiology and
Immunology, International Research Center for Infectious
Diseases, Institute of Medical Science, University of Tokyo,
Tokyo 108-8639, Japan; Core Research for Evolutional Science
and Technology, Japan Science and Technology Agency,
Kawaguchi, Saitama 332-0012, Japan; Daiichi Pharmaceutical,
Tokyo 134-8630, Japan; National Institute for Clinical
Research in Tropical Medicine, Hanoi, Vietnam; Department of
Biochemistry, University of Shizuoka, School of
Pharmaceutical Sciences and COE Program in the 21st Century,
Yada, Shizuoka-shi 422-8526, Japan; and Department of
Pathobiological Sciences, School of Veterinary Medicine,
University of Wisconsin, Madison, Wisconsin 53706, USA.]
References
----------
1. Enserink M. Science 2005; 309: 370�1.
2. Treanor JJ, et al. JAMA 2000; 283: 1016�24.
3. Gubareva LV, Kaiser L, Hayden FG. Lancet 2000; 355:
827�35.
4. Gubareva LV, Kaiser L, Matrosovich MN, Soo-Hoo Y, Hayden
FG. J Infect Dis 2001; 183: 523�31.
5. Zambon M, Hayden FG. Antiviral Res 2000; 47: 1�17.
6. Potier M, Mameli L, Belisle M, Dallaire L, Melancon SB.
Anal Biochem 1979; 94: 287�96.
7. Hurt AC, Barr IG, Gunter H, Hampson AW. Antiviral Res
2004; 62: 37�45.
8. Toms GLR, Bird RA, Kingsman SM, Sweet C, Smith H. Br J
Exp Pathol 1977; 57: 37�48.
9. Varghese JN, Laver WG, Colman PM. Nature 1983; 303:
35�50.
10. Varghese JN, McKimm-Breschkin JL, Caldwell JB, Kortt AA,
Colman PM. Proteins 1992; 11: 49�56.
11. Shinya K, et al. J Virol 2005; 79: 9926�32.
(The Supplementary information referred to above accompanies
this communication on Nature�s website. - Mod.CP]
--
ProMED-mail
<promed@promedmail.org>
See Also
Influenza viruses, drug resistance (04) 20051015.2999Influenza viruses, drug resistance (03) 20051007.2924
Influenza viruses, drug resistance (02): RFI 20051001.2878
Influenza viruses, drug resistance 20050930.2863
Avian influenza, human - East Asia (120): Viet Nam
20050901.2589
Avian influenza, human - East Asia (80): Viet Nam
20050519.1380
Avian influenza, poultry - China: antiviral treatment
20050621.1740
2004
---
Avian influenza - Eastern Asia (93): WHO statement
20040716.1935
Avian influenza A (H5N1) virus, human vaccine prospects
20040125.0300
Avian influenza A (H5N1) virus, drug resistance
20040125.0298
2001
---
Influenza virus, neuraminidase inhibitor resistance (02)
20010928.2372
Influenza virus, neuraminidase inhibitor resistance
20010926.2350
.............................cp/sh
*##########################################################*
************************************************************
ProMED-mail makes every effort to verify the reports that
are posted, but the accuracy and completeness of the
information, and of any statements or opinions based
thereon, are not guaranteed. The reader assumes all risks in
using information posted or archived by ProMED-mail. ISID
and its associated service providers shall not be held
responsible for errors or omissions or held liable for any
damages incurred as a result of use or reliance upon posted
or archived material.
************************************************************
Visit ProMED-mail's web site at <http://www.promedmail.org>.
Send all items for posting to: promed@promedmail.org
(NOT to an individual moderator). If you do not give your
full name and affiliation, it may not be posted. Send
commands to subscribe/unsubscribe, get archives, help,
etc. to: majordomo@promedmail.org. For assistance from a
human being send mail to: owner-promed@promedmail.org.
############################################################
############################################################