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(Created page with "{{WBRQuestion |QuestionAuthor={{Rim}} |ExamType=USMLE Step 1 |MainCategory=Biochemistry |SubCategory=General Principles |MainCategory=Biochemistry |SubCategory=General Princip...")
 
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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor={{YD}} (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Biochemistry
|MainCategory=Biochemistry
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|MainCategory=Biochemistry
|MainCategory=Biochemistry
|SubCategory=General Principles
|SubCategory=General Principles
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|MainCategory=Biochemistry
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|MainCategory=Biochemistry
|MainCategory=Biochemistry
|SubCategory=General Principles
|SubCategory=General Principles
|Prompt=A 78 year old man presents to the emergency department for pleuritic chest pain. Following appropriate work-up, the diagnosis of pneumonia by influenza virus 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?
|Prompt=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?
|Explanation=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.  
|Explanation=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.  
Educational Objective:
Clathrin-mediated endocytosis is required by some viruses, such as influenza virus, for cell entry.
Reference:
Lakadamyali M, Rust M, Zhuang X. Endocytosis of influenza virus. Microbes Infect. 2004; 6(10):929-936.
|AnswerA=Hemagglutinin
|AnswerA=Hemagglutinin
|AnswerAExp=Hemagglutinin is a viral factor that promotes viral entry.
|AnswerAExp=Hemagglutinin is a viral factor that promotes viral entry.
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|AnswerDExp=Kinesin is a protein that allows the transport of membrane-bound organelles from the (-) pole of the microtubule to its (+) pole.
|AnswerDExp=Kinesin is a protein that allows the transport of membrane-bound organelles from the (-) pole of the microtubule to its (+) pole.
|AnswerE=Hematin
|AnswerE=Hematin
|AnswerEExp=Hematin (factor X) is produced by H. influenza, gram negative bacteria, not by influenza virus.  
|AnswerEExp=Hematin (factor X) is produced by H. influenza, gram negative bacteria, not by influenza virus.
|EducationalObjectives=Clathrin-mediated endocytosis is required by some viruses, such as influenza virus, for cell entry.
|References=Lakadamyali M, Rust M, Zhuang X. Endocytosis of influenza virus. Microbes Infect. 2004; 6(10):929-936.
|RightAnswer=C
|RightAnswer=C
|WBRKeyword=clathrin, receptor, mediated, endocytosis, influenza, virus, infection
|WBRKeyword=Clathrin, Receptor mediated endocytosis, Endocytosis, Influenza, Influenza virus, Hemagglutinin
|Approved=No
|Approved=Yes
}}
}}

Revision as of 21:47, 5 March 2015
Author [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Serge Korjian)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Biochemistry
Sub Category SubCategory::General Principles
Prompt [[Prompt::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?]]
Answer A AnswerA::Hemagglutinin
Answer A Explanation AnswerAExp::Hemagglutinin is a viral factor that promotes viral entry.
Answer B AnswerB::Neuraminidase
Answer B Explanation AnswerBExp::Neuraminidase is a viral factor that promotes release of viral progeny.
Answer C AnswerC::Clathrin
Answer C Explanation AnswerCExp::Clathrin is a protein that mediates the uptake of compounds by endocytosis.
Answer D AnswerD::Kinesin
Answer D Explanation AnswerDExp::Kinesin is a protein that allows the transport of membrane-bound organelles from the (-) pole of the microtubule to its (+) pole.
Answer E AnswerE::Hematin
Answer E Explanation AnswerEExp::Hematin (factor X) is produced by H. influenza, gram negative bacteria, not by influenza virus.
Right Answer RightAnswer::C
Explanation [[Explanation::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.

Educational Objective: Clathrin-mediated endocytosis is required by some viruses, such as influenza virus, for cell entry.
References: Lakadamyali M, Rust M, Zhuang X. Endocytosis of influenza virus. Microbes Infect. 2004; 6(10):929-936.]]

Approved Approved::Yes
Keyword WBRKeyword::Clathrin, WBRKeyword::Receptor mediated endocytosis, WBRKeyword::Endocytosis, WBRKeyword::Influenza, WBRKeyword::Influenza virus, WBRKeyword::Hemagglutinin
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