Cases of Tamiflu (or other anti-viral resistance)

niman · **Posted:** Fri Aug 28, 2009 7:47 am

Commentary

http://www.recombinomics.com/News/08280 ... 4Y_CA.html

wotan · **Posted:** Fri Aug 28, 2009 9:11 am

niman wrote:

wotan wrote:

I think this is new. Tamiflu resistance confirmed in California?
http://www.cdph.ca.gov/programs/vrdl/Documents/InfluenzaUpdate082009.pdf

Quote:

During this week, the CDPH Viral and Rickettsial Diseases Laboratory detected a specimen with the H275Y resistance mutation (associated with oseltamivir resistance); the result was confirmed by the CDC. This is the first time that this mutation has been detected by the VRDL and provides strong evidence for the importance of enhanced surveillance for antiviral resistance testing. The specimen was obtained from a hospitalized patient in Northern California. To date, 308 specimens have been tested at VRDL for the resistance mutation; all but one have tested negative for the mutation. VRDL and CDC will continue prospective antiviral resistance testing from a sampling of pandemic (H1N1) 2009 influenza viruses through the summer and the 2009-10 influenza season.

Yes, this is new and of course northern California (San Francisco) is the origin of the case in Hong Kong where the traveler had a mild case and recivered with no Tamiflu resitance. It is not clear if this is the first hospitalized patient in the US who is not immunocompromised, since the above doesn't give details on the patient.

The UK is also listing a summary of WHO notified cases, and they show 4 from Japan, which is an increase of one over the cases I know of.

This report was released silently and apparently after hours yesterday. All the more interesting, this is California's week 32 surveillance. CDC's week 32 surveillance had the 2 in Washington and the announcement of 2 more in NC. The CDC has not updated their week 32 surveillance to reflect this report. Furthermore, I have seen no news coverage of this as of yet.

If I read it correctly, California reported 0 cases of seasonal flu in week 32.

wotan · **Posted:** Fri Aug 28, 2009 4:42 pm

http://www.cdc.gov/flu/weekly/

The CDC is reporting 6 cases of Tamiflu resistance but I can only account for 5 so far. 2 in Washington, 2 in NC, 1 in CA. Five of the 6 were receiving Tamiflu treatment, the sixth is being researched.

wotan · **Posted:** Fri Aug 28, 2009 4:46 pm

wotan wrote:

http://www.cdc.gov/flu/weekly/

The CDC is reporting 6 cases of Tamiflu resistance but I can only account for 5 so far. 2 in Washington, 2 in NC, 1 in CA. Five of the 6 were receiving Tamiflu treatment, the sixth is being researched.

The table says 6 cases but the text says 7:

Quote:

The majority of 2009 influenza A (H1N1) viruses are susceptible to the neuraminidase inhibitor antiviral medication oseltamivir, however rare sporadic cases of oseltamivir resistant 2009 influenza A (H1N1) viruses have been detected worldwide, including seven viruses in the United States. All tested viruses retain their sensitivity to the other neuraminidase inhibitor zanamivir. Additional information on antiviral recommendations for treatment and chemoprophylaxis of 2009 influenza A (H1N1) infection is available at http://www.cdc.gov/h1n1flu/recommendations.htm All 2009 influenza A (H1N1) viruses tested to date are resistant to the adamantane antiviral medications, amantadine and rimantadine. Antiviral treatment with either oseltamivir or zanamivir is recommended for all patients with confirmed, probable or suspected cases of 2009 influenza A (H1N1) virus infection who are hospitalized or who are at higher risk for seasonal influenza complications.

wotan · **Posted:** Fri Aug 28, 2009 5:05 pm

I can't account for two of the cases of Tamiflu resistance. Last week the CDC was reporting 4. Today it is 7. One of the new cases should be the one from California.

Texas has still not released their week 32 surveillance. A few weeks back there were reports of at least 2 cases of Tamiflu resistance in Texas that were later denied....

niman · **Posted:** Fri Aug 28, 2009 7:58 pm

wotan wrote:

I can't account for two of the cases of Tamiflu resistance. Last week the CDC was reporting 4. Today it is 7. One of the new cases should be the one from California.

Texas has still not released their week 32 surveillance. A few weeks back there were reports of at least 2 cases of Tamiflu resistance in Texas that were later denied....

Yes, I suspect these are Texas, but I am not sure Texas will admit it.

niman · **Posted:** Fri Aug 28, 2009 8:04 pm

wotan wrote:

I can't account for two of the cases of Tamiflu resistance. Last week the CDC was reporting 4. Today it is 7. One of the new cases should be the one from California.

Texas has still not released their week 32 surveillance. A few weeks back there were reports of at least 2 cases of Tamiflu resistance in Texas that were later denied....

Texas has tested THREE pandemic H1N1 isolates for antiviral resistance for the ENTIRE season (through week 31) and that is three above their credibility level.

gjs0708 · **Joined:** Thu Aug 27, 2009 1:21 pm **Posts:** 56

Quote:

the H275Y resistance mutation

I may have missed something earlier on this, but the 274 has been referenced before and this is 275. What does that mean? I haven't seen anyone specifically address the change from 274 to 275. Thank you.

wotan · **Posted:** Sat Aug 29, 2009 12:15 am

gjs0708 wrote:

Quote:

the H275Y resistance mutation

I may have missed something earlier on this, but the 274 has been referenced before and this is 275. What does that mean? I haven't seen anyone specifically address the change from 274 to 275. Thank you.

Dr. Niman can give a better answer but it is the same mutation, just using a slightly different notation. Perhaps think of it as like counting starting at either 0 or 1, the same offset but i off from each other (fencepost error).

niman · **Posted:** Sat Aug 29, 2009 3:23 am

gjs0708 wrote:

Quote:

the H275Y resistance mutation

I may have missed something earlier on this, but the 274 has been referenced before and this is 275. What does that mean? I haven't seen anyone specifically address the change from 274 to 275. Thank you.

The number is reaally related to the numbering "system". Much of the early structural work on influenza was based on H3N2, so many use an H3 numbering system for H and an N2 numbering system for N. For H1N1, some use an H1 numbering system for H and and N1 numbering for N. The change that confers Tamiflu resistance is H274Y in an N2 numbering system, while the same change designated H275Y in an N1 numbering system, so both names refer to the same change (and there is a different numbering for H5N1 because the N1 has a 20 aa deletion, but all changes are for the same position, and H changes to Y).

In fact the Tamiflu resistance in seasonal H1N1 and pandemic H1N1 all trace back to the change in H5N1 in Vietnam in 2005.

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