H1N1 - The latest news on the influenza

New paper:
Evidence for a novel gene associated with human influenza A viruses

Monica Clifford, James Twigg and Chris Upton (University of Victoria, BC)

See:
http://www.virologyj.com/content/6/1/198

In the recent Nature letter “In vitro and in vivo characterization of new swine-origin H1N1 influenza viruses“  Itoh, Y. et al. present findings from their characterization of pandemic H1N1.

Introduction:

Influenza A viruses cause recurrent outbreaks at local or global
scale with potentially severe consequences for human health and
the global economy. Recently, a new strain of influenza A virus was
detected that causes disease in and transmits among humans,
probably owing to little or no pre-existing immunity to the new
strain. On 11 June 2009 the World Health Organization declared
that the infections caused by the new strain had reached pandemic
proportion. Characterized as an influenza A virus of the H1N1
subtype, the genomic segments of the new strain were most closely
related to swine viruses1. Most human infections with swineorigin
H1N1 influenza viruses (S-OIVs) seem to be mild; however,
a substantial number of hospitalized individuals do not have
underlying health issues, attesting to the pathogenic potential of
S-OIVs. To achieve a better assessment of the risk posed by the new
virus, we characterized one of the first US S-OIV isolates,
A/California/04/09 (H1N1; hereafter referred to as CA04), as well
as several other S-OIV isolates, in vitro and in vivo. In mice and
ferrets, CA04 and other S-OIV isolates tested replicate more efficiently
than a currently circulating human H1N1 virus. In addition,
CA04 replicates efficiently in non-human primates, causes
more severe pathological lesions in the lungs of infected mice,
ferrets and non-human primates than a currently circulating
human H1N1 virus, and transmits among ferrets. In specificpathogen-
free miniature pigs, CA04 replicates without clinical
symptoms. The assessment of human sera from different age
groups suggests that infection with human H1N1 viruses antigenically
closely related to viruses circulating in 1918 confers neutralizing
antibody activity to CA04. Finally, we show that CA04 is
sensitive to approved and experimental antiviral drugs, suggesting
that these compounds could function as a first line of defence
against the recently declared S-OIV pandemic.

In Journal of Medicinal Chemistry (June 26, 2009) Sato and colleagues published findings on antiviral effects of sialylgalactose-binding peptides.

ScienceDaily (July 16, 2009) — Amid reports that swine flu viruses are developing the ability to shrug off existing antiviral drugs, scientists in Japan are reporting a first-of-its kind discovery that could foster a new genre of antivirals that sidestep resistance problems, according to a new article.

Access the latest in swine flu news and information for health care professionals at the ‘Pandemic flu’ website, provided by The British Medical Journal.  Here you can find a series of articles, podcasts and blogs discussing many aspects of the current influenza pandemic.

WHO Europe provides a website dedicated to the collection and presentation of data on influenza submitted by the Member States of the WHO European region.  It provides an interactive map showing the intensity of influenza activity and geographic spread.  You can also access weekly surveillance reports compiled from 53 participating countries.  Follow this link to EuroFlu.org to access the latest information.

H5N1 News and Resources about Pandemic Influenza congratulates Springer for making over 400 H1N1-related research articles available on SpringerLink at no charge for the rest of the year.

The review article “Historical Perspective - Emergence of Influenza A (H1N1) Viruses” reports the key steps that characterize the evolution of Influenza A.  In this article just published in the New England Journal of Medicine, Burke and Zimmer look at the emergence and spread of different Influenza A subtypes in the human population over the past 91 years.

Abstract: On April 17, 2009, officials at the Centers for Disease Control and Prevention (CDC) confirmed two cases of swine influenza in children living in neighboring counties in California.  Here we take a perspective from systems biology to review the series of evolutionary and epidemiologic events, starting in 1918, that led to the emergence of the current swine-origin influenza A (H1N1) strain (S-OIV), which is widely known as swine flu. This article is one of two historical articles on influenza A (H1N1) viruses in this issue of the Journal. Our review focuses on the key steps that characterize this viral evolution .

Tim Nolan on the BMJ  group Blogs comments on the spread of swine flu and how the spread has been calculated:

“We’re saying there have been at least a million cases of this new H1N1 virus in the United States so far this year. “
That’s according to the Centre for Disease Control (CDC) who held a press conference on Friday which shed some more light on the epidemiology and spread of the disease.
So how was this huge figure (over thirty times the number of confirmed cases) calculated?

In Nature 18th of June 2009, Kawaoka et al., publish on the pandemic potential of H1N1 influenza virus. Abstract: Influenza viruses cause annual epidemics and occasional pandemics that have claimed the lives of millions. The emergence of new strains will continue to pose challenges to public health and the scientific communities. A prime example is the recent emergence of swine-origin H1N1 viruses that have transmitted to and spread among humans, resulting in outbreaks internationally. Efforts to control these outbreaks and real-time monitoring of the evolution of this virus should provide us with invaluable information to direct infectious disease control programmes and to improve understanding of the factors that determine viral pathogenicity and/or transmissibility.

Determining how many people die from influenza is a tricky business.  In the virology blog How many people die from influenza? Vincent Racaniello looks at the 15th of June 2009 WHO report, confirming 35, 928 cases of influenza A(H1N1) infection in 76 countries, including 163 deaths.  These numbers are used to calculate a case fatality ratio (CFR) of 0.45%. Racaniello asks: Is this number an accurate indication of the lethality of influenza?