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Towards a sane and rational approach to management of Influenza H1N1 2009.

Gallaher WR - Virol. J. (2009)

Bottom Line: While reports are preliminary, through the first 4 weeks of the outbreak it does not appear to be severe either in terms of the attack rate in communities or in the virulence of the virus itself.However, there are significant changes in both the hemagglutinin and neuraminidase proteins of the new virus, 27.2% and 18.2% of the amino acid sequence, from prior H1N1 isolates in 2008 and the current vaccine.Perhaps balancing this shift, the novel virus retains more of the core influenza proteins from animal strains than successful human influenza viruses, and may be inhibited from its maximum potential until further reassortment or mutation better adapts it to multiplication in humans.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, 1901 Perdido Street, New Orleans, Louisiana 70112, USA. billg35445@yahoo.com

ABSTRACT
Beginning in March 2009, an outbreak of influenza in North America was found to be caused by a new strain of influenza virus, designated Influenza H1N1 2009, which is a reassortant of swine, avian and human influenza viruses. Over a thousand total cases were identified with the first month, chiefly in the United States and Mexico, but also involving several European countries. Actions concerning Influenza H1N1 2009 need to be based on fact and science, following recommendations of public health officials, and not fueled by political, legal or other interests. Every influenza outbreak or pandemic is unique, so the facts of each one must be studied before an appropriate response can be developed. While reports are preliminary, through the first 4 weeks of the outbreak it does not appear to be severe either in terms of the attack rate in communities or in the virulence of the virus itself. However, there are significant changes in both the hemagglutinin and neuraminidase proteins of the new virus, 27.2% and 18.2% of the amino acid sequence, from prior H1N1 isolates in 2008 and the current vaccine. Such a degree of change qualifies as an "antigenic shift", even while the virus remains in the H1N1 family of influenza viruses, and may give influenza H1N1 2009 significant pandemic potential. Perhaps balancing this shift, the novel virus retains more of the core influenza proteins from animal strains than successful human influenza viruses, and may be inhibited from its maximum potential until further reassortment or mutation better adapts it to multiplication in humans. While contact and respiratory precautions such as frequent handwashing will slow the virus through the human population, it is likely that development of a new influenza vaccine tailored to this novel Influenza H1N1 2009 strain will be essential to blunt its ultimate pandemic impact.

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Amino acid sequence alignment of the mature hemagglutinin (H) proteins of Influenza H1N1 2009 and its predecessor H1N1 isolated in 2008. The amino acid sequence of the H protein shown for the Influenza H1N1 2009 virus is derived from the segment 4 sequence of the isolate A/California/08/2009(H1N1) submitted from the CDC by Shu et al. on April 29, 2009, as Genbank FJ971076.  The sequence for Influenza H1N1 2008 is derived from the segment 4 sequence of the isolate A/District of Columbia/WRAMC-1154048/2008(H1N1) submitted from Walter Reed Army Institute of Research by Houng et al., collected from a patient on February 1, 2008, as Genbank CY038770. Only the sequences of the mature proteins, after cleavage of the signal sequence, are shown. Standard single-letter abbreviations for the amino acids are used. The collinear sequences were hand-aligned and also confirmed by online use of ClustalW. Amino acid positions showing differences between the two sequences are denoted with an “X”. There are 89 differences in 327 positions, or 27.2%. The canonical sites for N-linked glycosylation are  underlined. Amino acid regions contributing to each of five antigenic sites are labeled Site A through Site E.
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Figure 1: Amino acid sequence alignment of the mature hemagglutinin (H) proteins of Influenza H1N1 2009 and its predecessor H1N1 isolated in 2008. The amino acid sequence of the H protein shown for the Influenza H1N1 2009 virus is derived from the segment 4 sequence of the isolate A/California/08/2009(H1N1) submitted from the CDC by Shu et al. on April 29, 2009, as Genbank FJ971076. The sequence for Influenza H1N1 2008 is derived from the segment 4 sequence of the isolate A/District of Columbia/WRAMC-1154048/2008(H1N1) submitted from Walter Reed Army Institute of Research by Houng et al., collected from a patient on February 1, 2008, as Genbank CY038770. Only the sequences of the mature proteins, after cleavage of the signal sequence, are shown. Standard single-letter abbreviations for the amino acids are used. The collinear sequences were hand-aligned and also confirmed by online use of ClustalW. Amino acid positions showing differences between the two sequences are denoted with an “X”. There are 89 differences in 327 positions, or 27.2%. The canonical sites for N-linked glycosylation are underlined. Amino acid regions contributing to each of five antigenic sites are labeled Site A through Site E.

Mentions: Figure 1 shows an amino acid sequence alignment of Influenza H1N1 2009 with its predecessor HIN1 virus isolated the previous year, in 2008, at Walter Reed Army Hospital in Washington, DC. (The 2008 virus is in turn identical in amino acid sequence to the H antigen in the current influenza virus vaccine.) Each change in the sequence of Influenza H1N1 2009 from the 2008 virus is marked with an "X" in the alignment. It is obvious that H1N1 2009 is significantly novel, 27.2% different from the human H1N1 virus circulating in 2008 and the H antigen in the current vaccine. Also noted in the figure are the canonical sites for N-linked glycosylation of the protein, at NxS/T motifs (underlined), as well as the approximate positions of amino acids that determine the antigen specificity at five different protein loop regions on the surface of the protein, designated Site A through Site E [8]. It is obvious that the changes in amino acid sequence are concentrated in these antigenic sites. Additionally, one of the sites, Site C, may be blocked by a novel N-linked glycosylation at N277. All five of the known antigenic sites on the protein are therefore unique, and so no human herd immunity to this virus is to be expected anywhere in the human population of 6.77 billion persons. This constitutes a major antigenic shift which has in the past been the basis of major human pandemics.


Towards a sane and rational approach to management of Influenza H1N1 2009.

Gallaher WR - Virol. J. (2009)

Amino acid sequence alignment of the mature hemagglutinin (H) proteins of Influenza H1N1 2009 and its predecessor H1N1 isolated in 2008. The amino acid sequence of the H protein shown for the Influenza H1N1 2009 virus is derived from the segment 4 sequence of the isolate A/California/08/2009(H1N1) submitted from the CDC by Shu et al. on April 29, 2009, as Genbank FJ971076.  The sequence for Influenza H1N1 2008 is derived from the segment 4 sequence of the isolate A/District of Columbia/WRAMC-1154048/2008(H1N1) submitted from Walter Reed Army Institute of Research by Houng et al., collected from a patient on February 1, 2008, as Genbank CY038770. Only the sequences of the mature proteins, after cleavage of the signal sequence, are shown. Standard single-letter abbreviations for the amino acids are used. The collinear sequences were hand-aligned and also confirmed by online use of ClustalW. Amino acid positions showing differences between the two sequences are denoted with an “X”. There are 89 differences in 327 positions, or 27.2%. The canonical sites for N-linked glycosylation are  underlined. Amino acid regions contributing to each of five antigenic sites are labeled Site A through Site E.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2691743&req=5

Figure 1: Amino acid sequence alignment of the mature hemagglutinin (H) proteins of Influenza H1N1 2009 and its predecessor H1N1 isolated in 2008. The amino acid sequence of the H protein shown for the Influenza H1N1 2009 virus is derived from the segment 4 sequence of the isolate A/California/08/2009(H1N1) submitted from the CDC by Shu et al. on April 29, 2009, as Genbank FJ971076. The sequence for Influenza H1N1 2008 is derived from the segment 4 sequence of the isolate A/District of Columbia/WRAMC-1154048/2008(H1N1) submitted from Walter Reed Army Institute of Research by Houng et al., collected from a patient on February 1, 2008, as Genbank CY038770. Only the sequences of the mature proteins, after cleavage of the signal sequence, are shown. Standard single-letter abbreviations for the amino acids are used. The collinear sequences were hand-aligned and also confirmed by online use of ClustalW. Amino acid positions showing differences between the two sequences are denoted with an “X”. There are 89 differences in 327 positions, or 27.2%. The canonical sites for N-linked glycosylation are underlined. Amino acid regions contributing to each of five antigenic sites are labeled Site A through Site E.
Mentions: Figure 1 shows an amino acid sequence alignment of Influenza H1N1 2009 with its predecessor HIN1 virus isolated the previous year, in 2008, at Walter Reed Army Hospital in Washington, DC. (The 2008 virus is in turn identical in amino acid sequence to the H antigen in the current influenza virus vaccine.) Each change in the sequence of Influenza H1N1 2009 from the 2008 virus is marked with an "X" in the alignment. It is obvious that H1N1 2009 is significantly novel, 27.2% different from the human H1N1 virus circulating in 2008 and the H antigen in the current vaccine. Also noted in the figure are the canonical sites for N-linked glycosylation of the protein, at NxS/T motifs (underlined), as well as the approximate positions of amino acids that determine the antigen specificity at five different protein loop regions on the surface of the protein, designated Site A through Site E [8]. It is obvious that the changes in amino acid sequence are concentrated in these antigenic sites. Additionally, one of the sites, Site C, may be blocked by a novel N-linked glycosylation at N277. All five of the known antigenic sites on the protein are therefore unique, and so no human herd immunity to this virus is to be expected anywhere in the human population of 6.77 billion persons. This constitutes a major antigenic shift which has in the past been the basis of major human pandemics.

Bottom Line: While reports are preliminary, through the first 4 weeks of the outbreak it does not appear to be severe either in terms of the attack rate in communities or in the virulence of the virus itself.However, there are significant changes in both the hemagglutinin and neuraminidase proteins of the new virus, 27.2% and 18.2% of the amino acid sequence, from prior H1N1 isolates in 2008 and the current vaccine.Perhaps balancing this shift, the novel virus retains more of the core influenza proteins from animal strains than successful human influenza viruses, and may be inhibited from its maximum potential until further reassortment or mutation better adapts it to multiplication in humans.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, 1901 Perdido Street, New Orleans, Louisiana 70112, USA. billg35445@yahoo.com

ABSTRACT
Beginning in March 2009, an outbreak of influenza in North America was found to be caused by a new strain of influenza virus, designated Influenza H1N1 2009, which is a reassortant of swine, avian and human influenza viruses. Over a thousand total cases were identified with the first month, chiefly in the United States and Mexico, but also involving several European countries. Actions concerning Influenza H1N1 2009 need to be based on fact and science, following recommendations of public health officials, and not fueled by political, legal or other interests. Every influenza outbreak or pandemic is unique, so the facts of each one must be studied before an appropriate response can be developed. While reports are preliminary, through the first 4 weeks of the outbreak it does not appear to be severe either in terms of the attack rate in communities or in the virulence of the virus itself. However, there are significant changes in both the hemagglutinin and neuraminidase proteins of the new virus, 27.2% and 18.2% of the amino acid sequence, from prior H1N1 isolates in 2008 and the current vaccine. Such a degree of change qualifies as an "antigenic shift", even while the virus remains in the H1N1 family of influenza viruses, and may give influenza H1N1 2009 significant pandemic potential. Perhaps balancing this shift, the novel virus retains more of the core influenza proteins from animal strains than successful human influenza viruses, and may be inhibited from its maximum potential until further reassortment or mutation better adapts it to multiplication in humans. While contact and respiratory precautions such as frequent handwashing will slow the virus through the human population, it is likely that development of a new influenza vaccine tailored to this novel Influenza H1N1 2009 strain will be essential to blunt its ultimate pandemic impact.

Show MeSH
Related in: MedlinePlus