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Oseltamivir-resistant pandemic A/H1N1 virus is as virulent as its wild-type counterpart in mice and ferrets.

Hamelin ME, Baz M, Abed Y, Couture C, Joubert P, Beaulieu E, Bellerose N, Plante M, Mallett C, Schumer G, Kobinger GP, Boivin G - PLoS Pathog. (2010)

Bottom Line: Such increased levels of IL-6 were also observed in lymph nodes of ferrets infected with the mutant strain.Furthermore, the H274Y mutant strain was transmitted to ferrets.In conclusion, viral fitness of the H274Y pH1N1 isolate is not substantially altered and has the potential to induce severe disease and to disseminate.

View Article: PubMed Central - PubMed

Affiliation: CHUQ-CHUL Research Center in Infectious Diseases and Laval University, Québec City, Québec, Canada.

ABSTRACT
The neuraminidase inhibitor oseltamivir is currently used for treatment of patients infected with the pandemic A/H1N1 (pH1N1) influenza virus, although drug-resistant mutants can emerge rapidly and possibly be transmitted. We describe the characteristics of a pair of oseltamivir-resistant and oseltamivir-susceptible pH1N1 clinical isolates that differed by a single change (H274Y) in the neuraminidase protein. Viral fitness of pH1N1 isolates was assessed in vitro by determining replication kinetics in MDCK alpha2,6 cells and in vivo by performing experimental infections of BALB/c mice and ferrets. Despite slightly reduced propagation of the mutant isolate in vitro during the first 24 h, the wild-type (WT) and mutant resistant viruses induced similar maximum weight loss in mice and ferrets with an identical pyrexic response in ferrets (AUC of 233.9 and 233.2, P = 0.5156). Similarly, comparable titers were obtained for the WT and the mutant strains on days 1, 3, 6 and 9 post-infection in mouse lungs and on days 1-7 in ferret nasal washes. A more important perivascular (day 6) and pleural (days 6 and 12) inflammation was noted in the lungs of mice infected with the H274Y mutant, which correlated with increased pulmonary levels of IL-6 and KC. Such increased levels of IL-6 were also observed in lymph nodes of ferrets infected with the mutant strain. Furthermore, the H274Y mutant strain was transmitted to ferrets. In conclusion, viral fitness of the H274Y pH1N1 isolate is not substantially altered and has the potential to induce severe disease and to disseminate.

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Replicative capacities of wild-type (WT) and H274Y mutant isolates of pH1N1 and seasonal A/H1N1 viruses.Viral titers were determined at the indicated time points from supernatants of ST6Gal I-expressing MDCK cells infected with pH1N1 A/Québec/147023/2009 (WT), pH1N1 A/Québec/147365/2009 (H274Y mutant), A/Brisbane/59/07-like (WT) and A/Brisbane/59/07-like (H274Y mutant) isolates at a multiplicity of infection (MOI) of 0.001. Mean viral titers ± SD from triplicate experiments were determined by using standard plaque assays. * P<0.05 between the WT and H274Y pH1N1 viral titers.
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ppat-1001015-g001: Replicative capacities of wild-type (WT) and H274Y mutant isolates of pH1N1 and seasonal A/H1N1 viruses.Viral titers were determined at the indicated time points from supernatants of ST6Gal I-expressing MDCK cells infected with pH1N1 A/Québec/147023/2009 (WT), pH1N1 A/Québec/147365/2009 (H274Y mutant), A/Brisbane/59/07-like (WT) and A/Brisbane/59/07-like (H274Y mutant) isolates at a multiplicity of infection (MOI) of 0.001. Mean viral titers ± SD from triplicate experiments were determined by using standard plaque assays. * P<0.05 between the WT and H274Y pH1N1 viral titers.

Mentions: In vitro experiments performed in MDCK cells expressing the α2,6 sialic acid receptor indicated that the oseltamivir-resistant pH1N1 isolate replicated less efficiently than the WT pH1N1 during the first 24 h. However, there was no significant difference in viral titers subsequently i.e. from 36 to 72 h (Figure 1). The two pH1N1 isolates produced lower viral titers than seasonal A/H1N1 viruses (A/Brisbane/59/2007) including both a WT and a H274Y mutant at 36 and 48 h. Thus, the H274Y mutation resulted in either no impairment or only initial reduction in replicative capacities when inserted in seasonal and pandemic A/H1N1 backgrounds, respectively. Of note, the two pH1N1 viruses produced less well defined viral plaques on α2,6-transfected MDCK cells compared to seasonal strains (data not shown).


Oseltamivir-resistant pandemic A/H1N1 virus is as virulent as its wild-type counterpart in mice and ferrets.

Hamelin ME, Baz M, Abed Y, Couture C, Joubert P, Beaulieu E, Bellerose N, Plante M, Mallett C, Schumer G, Kobinger GP, Boivin G - PLoS Pathog. (2010)

Replicative capacities of wild-type (WT) and H274Y mutant isolates of pH1N1 and seasonal A/H1N1 viruses.Viral titers were determined at the indicated time points from supernatants of ST6Gal I-expressing MDCK cells infected with pH1N1 A/Québec/147023/2009 (WT), pH1N1 A/Québec/147365/2009 (H274Y mutant), A/Brisbane/59/07-like (WT) and A/Brisbane/59/07-like (H274Y mutant) isolates at a multiplicity of infection (MOI) of 0.001. Mean viral titers ± SD from triplicate experiments were determined by using standard plaque assays. * P<0.05 between the WT and H274Y pH1N1 viral titers.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908621&req=5

ppat-1001015-g001: Replicative capacities of wild-type (WT) and H274Y mutant isolates of pH1N1 and seasonal A/H1N1 viruses.Viral titers were determined at the indicated time points from supernatants of ST6Gal I-expressing MDCK cells infected with pH1N1 A/Québec/147023/2009 (WT), pH1N1 A/Québec/147365/2009 (H274Y mutant), A/Brisbane/59/07-like (WT) and A/Brisbane/59/07-like (H274Y mutant) isolates at a multiplicity of infection (MOI) of 0.001. Mean viral titers ± SD from triplicate experiments were determined by using standard plaque assays. * P<0.05 between the WT and H274Y pH1N1 viral titers.
Mentions: In vitro experiments performed in MDCK cells expressing the α2,6 sialic acid receptor indicated that the oseltamivir-resistant pH1N1 isolate replicated less efficiently than the WT pH1N1 during the first 24 h. However, there was no significant difference in viral titers subsequently i.e. from 36 to 72 h (Figure 1). The two pH1N1 isolates produced lower viral titers than seasonal A/H1N1 viruses (A/Brisbane/59/2007) including both a WT and a H274Y mutant at 36 and 48 h. Thus, the H274Y mutation resulted in either no impairment or only initial reduction in replicative capacities when inserted in seasonal and pandemic A/H1N1 backgrounds, respectively. Of note, the two pH1N1 viruses produced less well defined viral plaques on α2,6-transfected MDCK cells compared to seasonal strains (data not shown).

Bottom Line: Such increased levels of IL-6 were also observed in lymph nodes of ferrets infected with the mutant strain.Furthermore, the H274Y mutant strain was transmitted to ferrets.In conclusion, viral fitness of the H274Y pH1N1 isolate is not substantially altered and has the potential to induce severe disease and to disseminate.

View Article: PubMed Central - PubMed

Affiliation: CHUQ-CHUL Research Center in Infectious Diseases and Laval University, Québec City, Québec, Canada.

ABSTRACT
The neuraminidase inhibitor oseltamivir is currently used for treatment of patients infected with the pandemic A/H1N1 (pH1N1) influenza virus, although drug-resistant mutants can emerge rapidly and possibly be transmitted. We describe the characteristics of a pair of oseltamivir-resistant and oseltamivir-susceptible pH1N1 clinical isolates that differed by a single change (H274Y) in the neuraminidase protein. Viral fitness of pH1N1 isolates was assessed in vitro by determining replication kinetics in MDCK alpha2,6 cells and in vivo by performing experimental infections of BALB/c mice and ferrets. Despite slightly reduced propagation of the mutant isolate in vitro during the first 24 h, the wild-type (WT) and mutant resistant viruses induced similar maximum weight loss in mice and ferrets with an identical pyrexic response in ferrets (AUC of 233.9 and 233.2, P = 0.5156). Similarly, comparable titers were obtained for the WT and the mutant strains on days 1, 3, 6 and 9 post-infection in mouse lungs and on days 1-7 in ferret nasal washes. A more important perivascular (day 6) and pleural (days 6 and 12) inflammation was noted in the lungs of mice infected with the H274Y mutant, which correlated with increased pulmonary levels of IL-6 and KC. Such increased levels of IL-6 were also observed in lymph nodes of ferrets infected with the mutant strain. Furthermore, the H274Y mutant strain was transmitted to ferrets. In conclusion, viral fitness of the H274Y pH1N1 isolate is not substantially altered and has the potential to induce severe disease and to disseminate.

Show MeSH
Related in: MedlinePlus