New strain of bird flu packs a punch even after becoming drug-resistant

New strain of bird flu packs a punch even after becoming drug-resistant

Dec. 11, 2013 — Researchers at the Icahn School of Medicine at Mount Sinai reported that a virulent new strain of influenza -- the virus that causes the flu -- appears to retain its ability to cause serious disease in humans even after it develops resistance to antiviral medications. The finding was included in a study that was published today in the journal Nature Communications.

---

Share This:

It is not uncommon for influenza viruses to develop genetic mutations that make them less susceptible to anti-flu drugs. However, these mutations usually come at a cost to the virus, weakening its ability to replicate and to spread from one person to another.

Initial reports suggested that H7N9, an avian strain of influenza A that emerged in China last spring, could rapidly develop a mutation that made it resistant to treatment with the antiviral medication Tamiflu (oseltamivir). However, patients in whom drug resistance developed often had prolonged, severe infections and poor clinical outcomes. No vaccine is currently available to prevent H7N9, which infected at least 135 people and caused 44 deaths during the outbreak. In the absence of a vaccine, antiviral drugs are the only means of defense for patients who are infected with new strains of the flu.

"In this outbreak, we saw some differences in the behavior of H7N9 and other avian influenza strains that can infect humans, beginning with the rapid development of antiviral resistance in some people who were treated with oseltamivir and the persistence of high viral loads in those patients," said lead investigator Nicole Bouvier, MD, Assistant Professor of Medicine, Infectious Diseases at the Icahn School of Medicine at Mount Sinai.

Specifically, the investigators found that a drug-resistant H7N9 virus retained its ability to replicate in human respiratory cells and was comparable to a non-resistant form of the virus in producing severe illness in animal models. And although H7N9 appears to have a limited ability to spread readily from human to human, transmissibility in animal models was comparable between drug-susceptible and drug-resistant strains. "Transmission was inefficient for both of the H7N9 viruses that we tested in our experiments," said Dr. Bouvier. "But surprisingly, transmission of the drug-resistant virus was no less efficient than that of the drug-sensitive version."

"Many of the people infected with H7N9 during the outbreak in China were elderly or had other conditions that predisposed them to severe influenza illness," observed Dr. Bouvier. "Nevertheless, our study suggests that flu viruses can indeed develop drug-resistant mutations without suffering a penalty in terms of their own fitness."

Older antiviral drugs such as amantadine are no longer effective in treating most strains of the flu that infect humans. Newer antiviral drugs called neuraminidase inhibitors block an enzyme that helps the virus replicate. These drugs include Tamiflu, a pill, and Relenza (zanamivir), a powder that is inhaled. Both medications have drawbacks: flu viruses can develop resistance to the medications in people who take them, and, in many parts of the world, neither drug is available in an intravenous form to treat those with severe infections.

"Our study underscores the need to develop a bigger arsenal of antiviral drugs and vaccines, which will allow us to outsmart the influenza virus," said Dr. Bouvier. "Researchers at Mount Sinai are actively engaged in identifying new targets for drug therapy and are working to develop a universal vaccine that will prevent multiple strains of influenza."

Welcome to SUV System Ltd!

SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.

We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.

SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com

Electronic Components distributor:http://www.suvsystem.com

Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html

IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html

LED Distributor:http://www.suvsystem.com/l/LED-1.html

Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html

Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html

Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html

Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html

SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc

we are focus on the following fields,and hope we can help you.

Thin Film Resistors ST Transistors FAIRCHILD diodes Kingbrigt LED MAXIM IC ROHM Resistors Low Ohmic Resistors Discrete Semiconductor Transistors Rectifier Diodes SANYO IC PANASONIC Resistors NS IC TOSHIBA Diodes Switching Diodes Ligitek LED Industrial IC ON Diodes Fast Recovery Diodes Infineon Technologies Transistors Military IC Diodes ST Diodes Chip Fuses Chip Inductors HARRIS IC NEC Diodes TI IC LED part Thick Film Resistors BB IC Bipolar Transistors Resistor Arrays MOTOROLA IC ALTERA IC NXP Transistors High Precision Resistors components LINEAR IC Other Parts Current Sensors Resistors
http://www.suvsystem.com/a/7984.aspx