Disease relevance of HA

• We have analyzed sequence changes in the hemagglutinin and neuraminidase of influenza B viruses (and have determined four hemagglutinin sequences, of B/Bonn/43, B/USSR/100/83, B/Victoria/3/85, and B/Memphis/6/86) in relation to antigenic properties and compared these with similar analyses of variation in influenza A antigens [1].
• Two distinct regions of the influenza A/JAP/305/57 hemagglutinin molecule are identifiable as sites recognized by murine class I major histocompatibility complex (MHC) (H-2d)-restricted cytolytic T lymphocytes (CTL) generated in response to immunization with infectious type A influenza virus [2].
• Hemagglutinin (HA) is the major envelope glycoprotein of influenza A and B viruses, and hemagglutinin-esterase (HE) in influenza C viruses is a protein homologous to HA [3].
• Chimeric influenza A viruses with a functional influenza B virus neuraminidase or hemagglutinin [4].
• The neuraminidase of the reassortant viruses is most closely related to that of B/Victoria/2/87-like viruses currently circulating in Nanchang, China. A pattern of insertions and deletions in the hemagglutinin and the neuraminidase of different strains of influenza B viruses is observed [5].

Psychiatry related information on HA

• Mice intravenously injected with concentrated infectious influenza B/Lee/40 virus (LD50 = 6400 hemagglutinin units) developed lethargy, seizures, coma, and death 1 to 3 days later [6].

High impact information on HA

• A neuraminidase-inhibition assay and sequencing of the neuraminidase and hemagglutinin genes revealed no zanamivir-resistant variants [7].
• These observations show that even for a large complex glycoprotein molecule like the influenza hemagglutinin, only a limited number of class I CTL recognition sites are generated in the infected cell and that the subset of immunogenic epitopes is dependent on the MHC haplotype of the responding individual [2].
• Class I major histocompatibility complex-restricted cytolytic T lymphocytes recognize a limited number of sites on the influenza hemagglutinin [2].
• These same sites are not efficiently recognized by hemagglutinin-specific class I MHC-restricted CTL of several unrelated MHC haplotypes [2].
• METHODS: Clinical diagnosis, viral isolation, hemagglutinin inhibition serology, and multiplex, reverse transcription polymerase chain reaction were used to diagnose influenza in patients enrolled in international phase 3 studies designed to investigate the efficacy and safety of an anti-influenza drug (inhaled zanamivir) [8].

Chemical compound and disease context of HA

• The cytoplasmic tail (CT) of hemagglutinin (HA) of influenza B virus (BHA) contains at positions 578 and 581 two highly conserved cysteine residues (Cys578 and Cys581) that are modified with palmitic acid (PA) through a thioester linkage [9].
• Phylogenetic profiles of the genes coding for the hemagglutinin (HA) protein, nucleoprotein (NP), matrix (M) protein, and nonstructural (NS) proteins of influenza B viruses isolated from 1940 to 1998 were analyzed in a parallel manner in order to understand the evolutionary mechanisms of these viruses [10].
• Subunit vaccines containing hemagglutinin, neuraminidase, and nucleocapsids of A/Port Chalmers/1/73 (H3N2) influenza virus were prepared after treatment of purified virus with ammonium deoxycholate [11].
• Sucrose gradient-fractionated egg-derived antigen showed a single peak of hemagglutinin activity corresponding to whole virions, whereas MDCK-derived antigen contained two distinct peaks of hemagglutinin activity, one of which had a lower sedimentation rate [12].
• The hemagglutinin (HA) protein of influenza B virus contains a single arginine residue at its cleavage site and the HA0 precursor is not cleaved to the HA1 and HA2 subunits by tissue culture cell-associated proteases [13].

Biological context of HA

• The nucleotide sequences of the hemagglutinin gene of a new variant, B/Yamagata/16/88, had only 93.4% homology with those of two other viruses from the same epidemic [14].
• An analysis of nucleotide and amino acid substitutions of the hemagglutinin genes of influenza B viruses revealed that new and some old variants could cocirculate in the same epidemic [14].
• Influence of acylation sites of influenza B virus hemagglutinin on fusion pore formation and dilation [9].
• Twenty-nine subjects who received hemagglutinin-neuraminidase vaccine as their initial dose and commercial split-product vaccine as a booster dose had significantly lower antibody responses to influenza A/New Jersey/76 virus than subjects who received two doses of commercial split-product vaccine [15].
• The nucleotide sequence of the hemagglutinin HA1 region and the deduced amino acid sequence are presented [16].

Anatomical context of HA

• Taken together, these results strongly suggest that BM2 is integrated into the plasma membrane at the N-terminal hydrophobic domain as fourth membrane protein, in addition to hemagglutinin, neuraminidase, and NB, of the influenza B virus [17].
• Direct sequencing of viral RNA from the patient's nasopharynx and cerebrospinal fluid revealed identical nucleotide sequences in the HA1 region of the hemagglutinin gene [18].
• Viral propagation did not occur in liver or brain, but viral hemagglutinin, neuraminidase, and probably nucleoprotein antigens were produced in hepatocytes [6].
• The effect of macrophage (M)-tropic and T cell line (T)-tropic human immunodeficiency virus type 1 (HIV-1) infection on antigen-specific CD4 cytotoxic T lymphocytes (CTLs) has been studied using a CD4 CTL line specific for a peptide from influenza B virus hemagglutinin [19].
• Multi-cycle replication and plaque formation of influenza A and B viruses and cleavage activation of their hemagglutinin (HA) by an endogenous protease(s) were examined in two MDCK cell lines, MDCK(-) and MDCK(+) [20].

Associations of HA with chemical compounds

• Coexpression of NP and the P proteins in 293 cells was found to permit the expression and replication of a transfected model RNA based on segment 4 of B/Maryland/59, in which the hemagglutinin-coding region was replaced by a chloramphenicol acetyltransferase gene [21].
• Groups of mice were vaccinated three times intranasally (i.n.) with 10 microg of purified influenza B/Panama virus surface antigens (PSAs), which consist of hemagglutinin (HA) and neuraminidase (NA), either alone or admixed with chitosan or gellan solutions [22].
• Mutations (Asn-->Ser) at amino acids 145 and 150 were also found in the hemagglutinin gene of the B/HK/8/73 (HG) virus resistant to 4-guanidino-Neu5Ac2en [23].
• Both compounds, when administered intraperitoneally (i.p.), reduced lung consolidation and prolonged mean day of death, but ribavirin more effectively increased survivor number and lowered lung viral hemagglutinin (HA) titers [24].
• In timing of additional studies, hemagglutinin expression was inhibited to the greatest extent when LY253963 exposure was begun at least 8 h before viral infection, which suggested either slow uptake or intracellular metabolism of LY253963 to an active form [25].

Other interactions of HA

• Comparative analysis of evolutionary mechanisms of the hemagglutinin and three internal protein genes of influenza B virus: multiple cocirculating lineages and frequent reassortment of the NP, M, and NS genes [10].

Analytical, diagnostic and therapeutic context of HA

• Sequence analysis indicated that the hemagglutinin of Vero cell-derived influenza B viruses was identical to that of MDCK-grown counterparts but differed from that of egg-grown viruses at amino acid positions 196 to 198 [26].
• Compared to enzyme-linked immunosorbent assays, flow-based bead assays provided approximately 10-fold lower detection limit for viral particle detection and performed similarly for recombinant viral hemagglutinin protein detection [27].
• To examine the molecular epidemiology of influenza virus transmission, the nucleotide sequences of the HA1 domain of the hemagglutinin (HA) gene of 57 influenza A and 24 influenza B viruses recovered in a single season were analyzed [28].
• Probing the structure of influenza B hemagglutinin using site-directed mutagenesis [29].
• Multiplex reverse transcription (MRT) and multiplex PCR (MPCR) were used to amplify and differentiate the hemagglutinin (HA) genes of different types and subtypes of influenza viruses [30].

References