TY - JOUR AU - Schrauwen, Eefje J.A. AU - Herfst, Sander AU - Chutinimitkul, Salin AU - Bestebroer, Theo M. AU - Rimmelzwaan, Guus F. AU - Osterhaus, Albert D.M.E. AU - Kuiken, Thijs AU - Fouchier, Ron A.M. T1 - Possible Increased Pathogenicity of Pandemic (H1N1) 2009 Influenza Virus upon Reassortment T2 - Emerging Infectious Disease journal PY - 2011 VL - 17 IS - 2 SP - 200 SN - 1080-6059 AB - Since emergence of the pandemic (H1N1) 2009 virus in April 2009, three influenza A viruses—seasonal (H3N2), seasonal (H1N1), and pandemic (H1N1) 2009—have circulated in humans. Genetic reassortment between these viruses could result in enhanced pathogenicity. We compared 4 reassortant viruses with favorable in vitro replication properties with the wild-type pandemic (H1N1) 2009 virus with respect to replication kinetics in vitro and pathogenicity and transmission in ferrets. Pandemic (H1N1) 2009 viruses containing basic polymerase 2 alone or in combination with acidic polymerase of seasonal (H1N1) virus were attenuated in ferrets. In contrast, pandemic (H1N1) 2009 with neuraminidase of seasonal (H3N2) virus resulted in increased virus replication and more severe pulmonary lesions. The data show that pandemic (H1N1) 2009 virus has the potential to reassort with seasonal influenza viruses, which may result in increased pathogenicity while it maintains the capacity of transmission through aerosols or respiratory droplets. KW - Viruses KW - reassortment KW - pandemic (H1N1) 2009 KW - influenza KW - H1N1 KW - H3N2 KW - pathogenicity KW - transmission KW - ferrets KW - research KW - the Netherlands DO - 10.3201/eid1702.101268 UR - https://wwwnc.cdc.gov/eid/article/17/2/10-1268_article ER - End of Reference