Influenza A Virus

Influenza A Virus Antigenic Drift and Entry Mechanisms

• Influenza A viruses can infect a wide range of host species and have caused most influenza pandemics in history.
• Antigenic drift in influenza A viruses, particularly in the HA and NA genes, leads to the creation of new viral strains, necessitating updates to seasonal flu vaccines.
• Antigenic drift can result in changes in the hemagglutinin glycoprotein, particularly near the receptor-binding site, making the virus less recognizable to the immune system.
• The emergence of a new mutant form of hemagglutinin (HA), specifically the H1 subtype, in the 1918 Spanish Flu had a significant impact on the virulence of the virus.
• The lack of preexisting immunity to the new H1 subtype contributed to the rapid spread of the virus and increased severity of disease.
• The new H1 subtype may have undergone further mutations over time (antigenic drift), potentially altering the virus’s antigenic properties.
• Various mechanisms by which viruses can gain entry into host cells include pore-mediated penetration, endocytosis with dissolution of endosomal membrane, envelope fusion with plasma membrane, and endocytosis with fusion with endosomal membrane.
• Clathrin is a critical protein involved in clathrin-mediated endocytosis, a mechanism by which cells engulf molecules or particles from their external environment.
• Pore-mediated penetration involves the creation of pores in the host cell membrane through which the viral genome is injected, used by some human rhinoviruses and bacteriophages.
• Endocytosis involves the virus being engulfed by the host cell and forming an endosome, followed by dissolution of the endosomal membrane, used by adenoviruses.
• Envelope fusion with the plasma membrane allows certain viruses to enter the cell without being taken up into an endosome, employed by Morbilliviruses and Rubulaviruses.
• Endocytosis with fusion with the endosomal membrane allows some enveloped viruses to enter host cells through endocytosis, triggered by the low pH environment of the endosome, used by Herpes Simplex Virus and influenza viruses.

Influenza A Virus Antigenic Drift and Entry Mechanisms

• Influenza A viruses can infect a wide range of host species and have caused most influenza pandemics in history.
• Antigenic drift in influenza A viruses, particularly in the HA and NA genes, leads to the creation of new viral strains, necessitating updates to seasonal flu vaccines.
• Antigenic drift can result in changes in the hemagglutinin glycoprotein, particularly near the receptor-binding site, making the virus less recognizable to the immune system.
• The emergence of a new mutant form of hemagglutinin (HA), specifically the H1 subtype, in the 1918 Spanish Flu had a significant impact on the virulence of the virus.
• The lack of preexisting immunity to the new H1 subtype contributed to the rapid spread of the virus and increased severity of disease.
• The new H1 subtype may have undergone further mutations over time (antigenic drift), potentially altering the virus’s antigenic properties.
• Various mechanisms by which viruses can gain entry into host cells include pore-mediated penetration, endocytosis with dissolution of endosomal membrane, envelope fusion with plasma membrane, and endocytosis with fusion with endosomal membrane.
• Clathrin is a critical protein involved in clathrin-mediated endocytosis, a mechanism by which cells engulf molecules or particles from their external environment.
• Pore-mediated penetration involves the creation of pores in the host cell membrane through which the viral genome is injected, used by some human rhinoviruses and bacteriophages.
• Endocytosis involves the virus being engulfed by the host cell and forming an endosome, followed by dissolution of the endosomal membrane, used by adenoviruses.
• Envelope fusion with the plasma membrane allows certain viruses to enter the cell without being taken up into an endosome, employed by Morbilliviruses and Rubulaviruses.
• Endocytosis with fusion with the endosomal membrane allows some enveloped viruses to enter host cells through endocytosis, triggered by the low pH environment of the endosome, used by Herpes Simplex Virus and influenza viruses.

Influenza A Virus Antigenic Drift and Entry Mechanisms

• Influenza A viruses can infect a wide range of host species and have caused most influenza pandemics in history.
• Antigenic drift in influenza A viruses, particularly in the HA and NA genes, leads to the creation of new viral strains, necessitating updates to seasonal flu vaccines.
• Antigenic drift can result in changes in the hemagglutinin glycoprotein, particularly near the receptor-binding site, making the virus less recognizable to the immune system.
• The emergence of a new mutant form of hemagglutinin (HA), specifically the H1 subtype, in the 1918 Spanish Flu had a significant impact on the virulence of the virus.
• The lack of preexisting immunity to the new H1 subtype contributed to the rapid spread of the virus and increased severity of disease.
• The new H1 subtype may have undergone further mutations over time (antigenic drift), potentially altering the virus’s antigenic properties.
• Various mechanisms by which viruses can gain entry into host cells include pore-mediated penetration, endocytosis with dissolution of endosomal membrane, envelope fusion with plasma membrane, and endocytosis with fusion with endosomal membrane.
• Clathrin is a critical protein involved in clathrin-mediated endocytosis, a mechanism by which cells engulf molecules or particles from their external environment.
• Pore-mediated penetration involves the creation of pores in the host cell membrane through which the viral genome is injected, used by some human rhinoviruses and bacteriophages.
• Endocytosis involves the virus being engulfed by the host cell and forming an endosome, followed by dissolution of the endosomal membrane, used by adenoviruses.
• Envelope fusion with the plasma membrane allows certain viruses to enter the cell without being taken up into an endosome, employed by Morbilliviruses and Rubulaviruses.
• Endocytosis with fusion with the endosomal membrane allows some enveloped viruses to enter host cells through endocytosis, triggered by the low pH environment of the endosome, used by Herpes Simplex Virus and influenza viruses.