Question 193

Question:

Hepatitis A virus (HAV) is resistant to solvents such as chloroform and 20% diethyl ether, while HIV-1 is sensitive to such solvents. This resistance is best explained by absence of which of the following in HAV?

Correct Answer: E.  Viral envelope

Chloroform and diethyl ether are organic solvents that break down lipid membranes, such as viral envelope (choice E). Enveloped viruses, like HIV-1, acquire their envelopes from the plasma membrane as they exit the cell they infected. This membrane is largely made up of lipids. Naked viruses, like HAV, lack this lipid viral envelope, and are therefore resistant to chloroform and diethyl ether. An important way of classifying viruses is whether or not they have an envelope.
The other answer choices do not affect whether the virus is sensitive to organic solvents.