2017  0,977
2016  0,799
2015  0,662
2014  0,740
2013  0,739
2012  0,637
2011  0,658
2010  0,654
2009  0,570
2008  0,849
2007  0,805
2006  0,330
2005  0,435
2004  0,623
2003  0,567
2002  0,641
2001  0,490
2000  0,477
1999  0,762
1998  0,785
1997  0,507
1996  0,518
1995  0,502
Vol 52(2018) N 6 p. 891-898; DOI 10.1134/S0026893318060122 Full Text

N.F. Lomakina1,2*, G.K. Sadykova2, T.A. Timofeeva2, I.A. Rudneva2, E.Yu. Boravleva1, P.A. Ivanov2,3, A.G. Prilipov2, A.S. Gambaryan1

Three Mutations in the Stalk Region of Hemagglutinin Affect the pH of Fusion and Pathogenicity of H5N1 Influenza Virus

1Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products, Russian Academy of Sciences, Moscow, 108819 Russia
2N.F. Gamaleya National Center of Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, 123098 Russia
3The Mental Health Research Center, Moscow, 115522 Russia

Received - 2018-04-09; Accepted - 2018-05-16

Previously, an attenuated variant Ku/at was obtained from the highly pathogenic avian influenza virus A/chicken/Kurgan/3/2005 (H5N1) by a reverse selection method aimed at increasing the virus resistance to a proteolytic cleavage and acidic pH values. In the Ku/at, 10 mutations in proteins PB2, PB1, HA, NA, and NS1 occurred. In comparison with the parental strain, the pH of the conformational transition of the viral glycoprotein hemagglutinin (HA) and virulence for mice and chickens have decreased in an attenuated variant. The purpose of this work is to clarify the role of three mutations in the stalk region of HA: Asp54Asn in HA1 and Val48Ile and Lys131Thr in HA2 (H3 HA numbering). To attain these ends, analogous substitutions were introduced into HA with a deleted polybasic cleavage site (important for pathogenicity) of the recombinant A/Vietnam/1203/04-PR8/CDC-RG (H5N1) virus, and so we created the VN3x-PR variant. Viruses VN3x-PR and Ku/at with the same three mutations, but different proteolytic cleavage sites in HA, as well as the corresponding initial viruses, were tested for pathogenicity in mice and in the erythrocyte hemolysis test. Compared with the parental strains, the virulence of their mutant variants in the case of intranasal infection of BALB/c mice decreased by 4-5 orders of magnitude, and the pH of the conformational transition of HA decreased from 5.70-5.80 to 5.25-5.30, which is typical for low pathogenic natural isolates. Thus, as a result of the study, the attenuating role of these three mutations in HA has been proved, a correlation was established between the pH value of the HA conformational transition and the virulence of H5N1 influenza viruses, and it was shown that the polybasic cleavage site of the H5 HA does not always determine high pathogenicity of the virus.

influenza A virus, H5N1, hemagglutinin, amino acid substitutions, reverse genetics, reverse selection, attenuation