Comments on: Brazilian influenza H1N1 isolate is not novel

By: profvrr

profvrr — Tue, 23 Jun 2009 23:19:35 +0000

We don't know why apparently healthy people have influenza
complications. I suspect that many such individuals have slightly
sub-optimal immune responses that allow unchecked virus replication.
For example, the innate immune response (see previous posts at
virology blog) is crucial for blocking most virus infections; if a key
component of this system is slightly altered, lethal infections may
occur.

By: profvrr

profvrr — Tue, 23 Jun 2009 16:19:35 +0000

By: SCIENCEPODCASTERS.ORG » This Week in Virology #37: Open Access

SCIENCEPODCASTERS.ORG » This Week in Virology #37: Open Access — Tue, 23 Jun 2009 16:10:23 +0000

[...] manufacturing of two enzyme drugs because of vesivirus contamination Brazilian H1N1 isolate is not novel WHO interactive H1N1 map Targeting children maximizes the effect of vaccination Chikungunya virus [...]

By: TWiV 37: Open access

TWiV 37: Open access — Sun, 21 Jun 2009 13:40:57 +0000

[...] down manufacturing of two enzyme drugs because of vesivirus contamination Brazilian H1N1 isolate is not novel WHO interactive H1N1 map Targeting children maximizes the effect of vaccination Chikungunya virus [...]

By: Riding the influenza pandemic wave

Riding the influenza pandemic wave — Fri, 19 Jun 2009 17:33:48 +0000

[...] more virulent. Nevertheless, speculation is rampant, and accompanied the recent release of the Brazilian isolate. Another example is an amino acid change in the viral PB2 protein observed in some 2009 H1N1 [...]

By: phogdog

phogdog — Thu, 18 Jun 2009 20:56:56 +0000

If I were Vince, I would see if I could figure out a way to take his podcast team down to Sao Paulo for some personal investigation, and maybe a day on the beach.

By: phytosleuth

phytosleuth — Thu, 18 Jun 2009 17:43:28 +0000

Rancaniello rocks! Thanks profrr.

By: profvrr

profvrr — Thu, 18 Jun 2009 17:14:31 +0000

All the data on the effect of the PB2 E627K change on host range,
virulence, and temperature restriction have been acquired in animal
models or cell cultures. The observations with the 1918 strain and the
H7N7 death are associations, not proof of any causative role of the
E627K change. Whether or not PB2 E627K would lead to increased
virulence in humans is unknown and remains highly speculative. One way
to address this question would be to isolate the 2009 H1N1 virus from
cases of primary viral pneumonia, e.g. those where the virus has
replicated in the lower respiratory tract where the temperature is
higher than in the upper tract. The goal would be to determine if
replication in the lower tract is associated with the change E627K.
Other amino acid changes are likely to be involved. For example, there
is a recent report which concludes that "the E627K mutation of PB2 is
not an indispensable determinant in PB2 for mammalian adaptation by
H5N1 avian influenza virus".

By: phytosleuth

phytosleuth — Thu, 18 Jun 2009 13:13:01 +0000

Could you comment on the Shanghai isolate? Thanks. See Recombinomics recent posting:

http://www.recombinomics.com/News/06180901/H1N1...

By: ElDean

ElDean — Thu, 18 Jun 2009 07:11:57 +0000

Just Wait and Watch

By: JD

JD — Thu, 18 Jun 2009 03:12:53 +0000

I'm pretty sure that at least some of the deaths in healthy people have been due to a cytokine storm. I've heard in several reports that the cause of death was multiple organ failure and at least one victim was vomiting up blood before he died. But that in itself doesn't tell us whether the virus is becoming more virulent. Remember, in the Mexican outbreak at least half the fatalities were in healthy young adults who succumbed to viral pneumonia, but the virus was and is still 'mild' for the most part, meaning that most people who catch it, including healthy young adults, will perhaps suffer a week of hell but then recover. And studies by Peter Palese and others have shown that the new virus is lacking in key protein components that are believed to determine or at least influence virulence. The question that really bugs me is whether the virus is starting to mutate into a much more virulent form, so that we will see many more fatalities proportionally than we are seeing now.

By: Jason Tetro

Jason Tetro — Thu, 18 Jun 2009 00:40:06 +0000

I think we need to know whether the death (or any of the deaths) was due to cytokine storm. If so, then we have reason for concern. If there is a greater opportunity for secondary infection, this too will need investigation. But until we have also the clinical information, we're very much in the dark.

By: JD

JD — Wed, 17 Jun 2009 23:48:12 +0000

Dr. Racaniello,
Thank you for your excellent blog, which I just found and have started following. I had heard that the swine flu virus so far has not changed form, but a recent death in San Diego county gave me pause:

http://www3.signonsandiego.com/stories/2009/jun...

Especially worrying to me was the following:

" She started having respiratory problems Sunday...The patient died in the emergency room without being hospitalized...the victim was apparently healthy before this illness and had not traveled outside the region."

Of course the news story is a bit ambiguous here, as the woman's symptoms could have started several days before and only on Sunday did she develop severe respiratory problems...but the speed of the deterioration seems striking here, as well as the fact that she was previously healthy. Could this mean that the virus is becoming more aggressive? Of course we already know that about half the Mexican deaths due to swine flu were in previously healthy young people.

I guess my question is, people have been saying that the virus is generally mild, and certainly most people seem to recover from it. But do we know anything about why some healthy young people recover from swine flu while others are ravaged and killed?

By: Brazilian influenza H1N1 isolate is not novel | Swine Flu Outbreak

Brazilian influenza H1N1 isolate is not novel | Swine Flu Outbreak — Wed, 17 Jun 2009 19:10:38 +0000

[...] Read the rest here: Brazilian influenza H1N1 isolate is not novel [...]

By: profvrr

profvrr — Wed, 17 Jun 2009 16:55:26 +0000

In addition, the identity of the San Paulo strain with some other
early isolates (e.g. Texas) also indicates that there is nothing to
worry about.

By: Jason Tetro

Jason Tetro — Wed, 17 Jun 2009 16:50:26 +0000

I already Twittered the HA aa differences between the California/04/2009 and the San Paulo/1454/2009. Two changes that could lead to some variation P100S and T214A but nothing that should create any kind of panic.