SAN DIEGO – The neuraminidase inhibitor peramivir inhibited about 99% of seasonal influenza A and B viruses circulating globally during the 2013-2014 and 2014-2015 influenza seasons, a large analysis demonstrated.
“The frequency of H1N1pdm09 viruses carrying neuraminidase (NA) H275Y remained low during both seasons; this mutation confers resistance to oseltamivir and peramivir,” said Margaret Okomo-Adhiambo, Ph.D., at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy. In addition, “a small proportion of viruses contained other neuraminidase changes that affect binding of peramivir to viral enzymes and may decrease virus susceptibility. These changes need to be closely monitored.”
Dr. Margaret Okomo-Adhiambo
Approved by the FDA in December of 2014, peramivir (Rapivab) is the only antiviral agent for influenza treatment to come to market in nearly 20 years. Approved for intravenous administration as a single dose, it is indicated for adults with acute uncomplicated influenza who may have trouble taking orally administered or inhaled neuraminidase (NA) inhibitors. Other NA inhibitors approved by the FDA for influenza infection include oseltamivir, which is orally administered, and zanamivir, which is inhaled.
For the current analysis, Dr. Okomo-Adhiambo of the influenza division at the Centers for Disease Control and Prevention, Atlanta, and her associates tested influenza virus susceptibility to peramivir during the 2013-2014 and 2014-2015 influenza seasons as part of the World Health Organization Global Influenza Surveillance and Response System. A total of 8,426 viruses were tested, 75% of which were circulating in the United States.
Dr. Okomo-Adhiambo reported that during the 2013-2014 and 2014-2015 influenza seasons, about 99% of influenza type A and B viruses were inhibited by peramivir, except for a few viruses belonging to subtype A(H1N1)pdm09 (1.5%), subtype A(H3N2) (0.2%), and type B (0.4%). In addition, NA activity of type A viruses was five to six times more sensitive to inhibition by peramivir, compared with type B NA.
She concluded her presentation by noting that studies “are needed to establish molecular markers of clinically relevant resistance to peramivir.”
The researchers reported having no financial disclosures.