Theresa42
Well-known member
Current Science, Vol. 92, No. 7, 10 April 2007
pp. 894-95
Scientific Correspondence:
Mutational analysis of H5N1 and H1H1 for ascertaining test systems
Bird flu (also known as avian influenza, avian flu, influenza virus A, type A flu, or genus A flu) is a type of influenza virus that is hosted by birds, but may infect several species of mammals. H5N1 is a highly pathogenic strain of bird flu. The first known appearance of this type of influenza in humans1 was in Hong Kong during 1997. The name H5N1 refers to the subtypes of surface antigens present on the virus: hemagglutinin type 5 and neuraminidase type 1. Normally, avian flu viruses are transported worldwide in the intestines of wild birds, and are nonlethal. Infected birds pass on H5N1 through their saliva, nasal secretions and faeces. Because migratory birds are among the carriers of the H5N1 virus, it may spread to all parts of the world. There are three types of influenza viruses, namely A, B and C, which are classified on the basis of nucleoproteins. Among these, influenza A virus has a pandemic potential. There are two important surface glycoproteins, hemagglutinin (HA), and neuraminidase (NA), which are embedded in the virus membrane. Hemagglutinin mediates receptor binding and membrane fusion, whereas neuraminidase facilitates cleavage of the viral progeny from infected cells. There are 16 H and 9 N subtypes of the influenza A virus2. Totally 144 HA and NA combinations are possible, out of which 103 have been confirmed. The avian influenza A virus (AIV) that contains the HA subtypes H3, H4, H6 is the most frequently isolated, whereas AIV of subtypes H5 and H7 was less frequently encountered. All other HAs are rather rare. AIV that possesses the NA of subtypes N2, N1, N8 and N3 is frequent and all other NAs are rarely detected3. There are two models of mutations associated with influenza virus, namely antigen shift and antigen drift4.
The H5N1 genome has eight segments (1?8), each segment codes for a protein: polymerase* (PB2), polymerase (PB1), polymerase (none), hemagglutanin (none), nucleocapsid (none), neuraminidase (NA), matrix protein 2(M) and nonstructural protein respectively.
Lysine (K) at position 627 of H1N1 (1918) has mutated to glutamic acid (E) in H5N1 (K627E), which is known to be pandemic for humans. This finding has resulted in a new approach of vaccine treatment for bird flu.
We notice one more mutation at position 628 which changes glutamine(Q) in H1N1 to proline(P) in H5N1 (Q627P), but this mutation has no effect on the protein function.
H1N1 PB2 gene ?A(623)APPK(627)Q-(628)S? changes into ?A(623)APPE(627)-P(628)S?.
There are two domains present in segment of H5N1 genome, whose Prodom Domain ID is PD001667 and PD217887. However, position 627 comes under domain PD001667.
Secondary structure of segment 1 of H5N1 and H1N1 is almost similar according to the SOPMA secondary structure prediction. There are minor changes found in the extended strands and random coils, where the alpha helix is the same in H5N1 and H1N1.
Results have shown that the protein sequence of H5N1 is close to H1N1, but there are minor changes found due to a single mutation. Deletion of one amino acid at 627 is mainly responsible for the mutation. This leads to the new approach of vaccine treatment for bird flu. There are two domains found in segment 1 of H5N1 genome. The result of SOPMA shows that there are 284 alpha helices, 176 extended strands, 66 beta turns and 233 random coils present in the secondary structure.
1. Chan, P. K., Clin. Infect. Dis., 2002, 34, S58?S64.
2. Wu, Tsung-Zu and Huang, Li-Min, Chang Gung Med. J., 11 November 2005, 28.
3. Kaleta, E. F., Hergarten, G. and Yilmaz, A., Dtsch. Tierarztl. Wochenschr., 2005, 112, 448?456.
4. Nicholson, K. G., Wood, J. M. and Zambon, M., Lancet, 2003, 362, 1733?1745.
Received 7 June 2006; revised accepted 23 November 2006
DHARMENDRA KUMAR*
PUSHPA AGRAWAL
PRASHANTHA V. SARADESAI
B. J. ARAVINDA
SHREYASH N. DESHPANDE
Department of Biotechnology,
R.V. College of Engineering,
R.V. Vidhyaniketan Post,
Mysore Road,
Bangalore 560 059, India
*For correspondence.
e-mail: dk_bioinfo _at_ yahoo.com
http://www.ias.ac.in/currsci/apr102007/894.pdf
pp. 894-95
Scientific Correspondence:
Mutational analysis of H5N1 and H1H1 for ascertaining test systems
Bird flu (also known as avian influenza, avian flu, influenza virus A, type A flu, or genus A flu) is a type of influenza virus that is hosted by birds, but may infect several species of mammals. H5N1 is a highly pathogenic strain of bird flu. The first known appearance of this type of influenza in humans1 was in Hong Kong during 1997. The name H5N1 refers to the subtypes of surface antigens present on the virus: hemagglutinin type 5 and neuraminidase type 1. Normally, avian flu viruses are transported worldwide in the intestines of wild birds, and are nonlethal. Infected birds pass on H5N1 through their saliva, nasal secretions and faeces. Because migratory birds are among the carriers of the H5N1 virus, it may spread to all parts of the world. There are three types of influenza viruses, namely A, B and C, which are classified on the basis of nucleoproteins. Among these, influenza A virus has a pandemic potential. There are two important surface glycoproteins, hemagglutinin (HA), and neuraminidase (NA), which are embedded in the virus membrane. Hemagglutinin mediates receptor binding and membrane fusion, whereas neuraminidase facilitates cleavage of the viral progeny from infected cells. There are 16 H and 9 N subtypes of the influenza A virus2. Totally 144 HA and NA combinations are possible, out of which 103 have been confirmed. The avian influenza A virus (AIV) that contains the HA subtypes H3, H4, H6 is the most frequently isolated, whereas AIV of subtypes H5 and H7 was less frequently encountered. All other HAs are rather rare. AIV that possesses the NA of subtypes N2, N1, N8 and N3 is frequent and all other NAs are rarely detected3. There are two models of mutations associated with influenza virus, namely antigen shift and antigen drift4.
The H5N1 genome has eight segments (1?8), each segment codes for a protein: polymerase* (PB2), polymerase (PB1), polymerase (none), hemagglutanin (none), nucleocapsid (none), neuraminidase (NA), matrix protein 2(M) and nonstructural protein respectively.
Lysine (K) at position 627 of H1N1 (1918) has mutated to glutamic acid (E) in H5N1 (K627E), which is known to be pandemic for humans. This finding has resulted in a new approach of vaccine treatment for bird flu.
We notice one more mutation at position 628 which changes glutamine(Q) in H1N1 to proline(P) in H5N1 (Q627P), but this mutation has no effect on the protein function.
H1N1 PB2 gene ?A(623)APPK(627)Q-(628)S? changes into ?A(623)APPE(627)-P(628)S?.
There are two domains present in segment of H5N1 genome, whose Prodom Domain ID is PD001667 and PD217887. However, position 627 comes under domain PD001667.
Secondary structure of segment 1 of H5N1 and H1N1 is almost similar according to the SOPMA secondary structure prediction. There are minor changes found in the extended strands and random coils, where the alpha helix is the same in H5N1 and H1N1.
Results have shown that the protein sequence of H5N1 is close to H1N1, but there are minor changes found due to a single mutation. Deletion of one amino acid at 627 is mainly responsible for the mutation. This leads to the new approach of vaccine treatment for bird flu. There are two domains found in segment 1 of H5N1 genome. The result of SOPMA shows that there are 284 alpha helices, 176 extended strands, 66 beta turns and 233 random coils present in the secondary structure.
1. Chan, P. K., Clin. Infect. Dis., 2002, 34, S58?S64.
2. Wu, Tsung-Zu and Huang, Li-Min, Chang Gung Med. J., 11 November 2005, 28.
3. Kaleta, E. F., Hergarten, G. and Yilmaz, A., Dtsch. Tierarztl. Wochenschr., 2005, 112, 448?456.
4. Nicholson, K. G., Wood, J. M. and Zambon, M., Lancet, 2003, 362, 1733?1745.
Received 7 June 2006; revised accepted 23 November 2006
DHARMENDRA KUMAR*
PUSHPA AGRAWAL
PRASHANTHA V. SARADESAI
B. J. ARAVINDA
SHREYASH N. DESHPANDE
Department of Biotechnology,
R.V. College of Engineering,
R.V. Vidhyaniketan Post,
Mysore Road,
Bangalore 560 059, India
*For correspondence.
e-mail: dk_bioinfo _at_ yahoo.com
http://www.ias.ac.in/currsci/apr102007/894.pdf
I was hoping someone else could explain it.... 
