]> 2026-07-31T09:40:49+00:00 WBR0848 0 en Hemagglutinin Hemagglutinin is a viral factor that promotes viral entry. Neuraminidase Neuraminidase is a viral factor that promotes release of viral progeny. Clathrin Clathrin is a protein that mediates the uptake of compounds by endocytosis. Kinesin Kinesin is a protein that allows the transport of membrane-bound organelles from the (-) pole of the microtubule to its (+) pole. Hematin Hematin (factor X) is produced by H. influenza, gram negative bacteria, not by influenza virus. Influenza virus is an enveloped virus that contains 3 major proteins: Hemagglutinin (HA), neuromanidase (NA), and M2 that are present on its lipid bilayer membrane. Protein matrix under the lipid bilayer membrane is made of M1 protein. Viral entry into the cells starts with viral internalization by receptor-mediated endocytosis. Viruses are then trafficked along the endocytic pathway to endosomes. Viral factors, such as HA and NA are needed for the attachment of the virus to the cell and subsequent entry. At the same time, host factors, such as clathrin, are needed for the endocytosis. Clathrin is a protein that is important for the formation of vesicles needed for endocytosis. Clathrin is a large protein with light and heavy chains that forms "clathrin-coated vesicles" (CCV). It is able to transport proteins inside the cells between organelles to their target destination.<br/> '''Educational Objective:''' Clathrin-mediated endocytosis is required by some viruses, such as influenza virus, for cell entry.<br/> '''References:''' Lakadamyali M, Rust M, Zhuang X. Endocytosis of influenza virus. Microbes Infect. 2004; 6(10):929-936. Biochemistry A 78-year-old man presents to the emergency department for pleuritic chest pain. Following a complete work-up, the diagnosis of viral pneumonia due to influenza is made. The physician explains that in addition to viral factors, host factors are also needed for an infection to occur. Which of the following host factors is required for the influenza virus to enter the cell? C General Principles 2020-10-28T01:52:38Z 2459150.5782176 WBR0848