Question 3: The principal determinant of HIV tropism resides in the surface envelope (Env; gp160) glycoprotein spike. The CD4 molecule, found on a subset of T cells, was identified as the major cell-surface receptor for HIV. However, later work showed that mouse cells expressing human CD4 were not able to be infected with HIV [mouse cells are not permissive for HIV infection normally]. To experimentally address this puzzling issue, researchers tested the ability of heterokaryons, which are essentially just fused cells with more than one nucleus, made from two sources: (1) mouse cells engineered to express human CD4 and (2) human cells that did not express CD4. The researchers then induced fusion between these two cell types to create the heterokaryons. Using this system, researchers observed that CD4+ mouse/human heterokaryons - but not CD4+ mouse/monkey heterokaryons - were able to be infected with HIV. Provide an explanation for these findings and what they revealed about the mechanism by which HIV enters cells.
Question 3: The principal determinant of HIV tropism resides in the surface envelope (Env; gp160) glycoprotein spike. The CD4 molecule, found on a subset of T cells, was identified as the major cell-surface receptor for HIV. However, later work showed that mouse cells expressing human CD4 were not able to be infected with HIV [mouse cells are not permissive for HIV infection normally]. To experimentally address this puzzling issue, researchers tested the ability of heterokaryons, which are essentially just fused cells with more than one nucleus, made from two sources: (1) mouse cells engineered to express human CD4 and (2) human cells that did not express CD4. The researchers then induced fusion between these two cell types to create the heterokaryons. Using this system, researchers observed that CD4+ mouse/human heterokaryons - but not CD4+ mouse/monkey heterokaryons - were able to be infected with HIV. Provide an explanation for these findings and what they revealed about the mechanism by which HIV enters cells.
Human Anatomy & Physiology (11th Edition)
11th Edition
ISBN:9780134580999
Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:Elaine N. Marieb, Katja N. Hoehn
Chapter1: The Human Body: An Orientation
Section: Chapter Questions
Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...
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![Question 3:
The principal determinant of HIV tropism resides in the surface envelope (Env; gp160) glycoprotein spike.
The CD4 molecule, found on a subset of T cells, was identified as the major cell-surface receptor for HIV.
However, later work showed that mouse cells expressing human CD4 were not able to be infected with
HIV [mouse cells are not permissive for HIV infection normally]. To experimentally address this puzzling
issue, researchers tested the ability of heterokaryons, which are essentially just fused cells with more than
one nucleus, made from two sources: (1) mouse cells engineered to express human CD4 and (2) human
cells that did not express CD4. The researchers then induced fusion between these two cell types to create
the heterokaryons. Using this system, researchers observed that CD4+ mouse/human heterokaryons - but
not CD4+ mouse/monkey heterokaryons – were able to be infected with HIV. Provide an explanation for
these findings and what they revealed about the mechanism by which HIV enters cells.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F43e5234f-f926-4bd8-baef-e8175c50855a%2Ff42ea806-fa98-4963-998a-799d4c9855b0%2Fwbj8py_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Question 3:
The principal determinant of HIV tropism resides in the surface envelope (Env; gp160) glycoprotein spike.
The CD4 molecule, found on a subset of T cells, was identified as the major cell-surface receptor for HIV.
However, later work showed that mouse cells expressing human CD4 were not able to be infected with
HIV [mouse cells are not permissive for HIV infection normally]. To experimentally address this puzzling
issue, researchers tested the ability of heterokaryons, which are essentially just fused cells with more than
one nucleus, made from two sources: (1) mouse cells engineered to express human CD4 and (2) human
cells that did not express CD4. The researchers then induced fusion between these two cell types to create
the heterokaryons. Using this system, researchers observed that CD4+ mouse/human heterokaryons - but
not CD4+ mouse/monkey heterokaryons – were able to be infected with HIV. Provide an explanation for
these findings and what they revealed about the mechanism by which HIV enters cells.
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