Question 1

Which of the following is a likely purpose for the noninfectious particles produced by hepatitis B virus?

Accepted Answer

Noninfectious particles produced by hepatitis B virus, known as "empty" or "subviral" particles, lack the viral genome and are unable to infect cells. However, these particles can bind to antibodies, which may divert the immune response away from the infectious virions, allowing the virus to evade the immune system.

Question 2

The copy of the hepatitis B virus genome that is inside of the virion has unusual structures as the 5' and 3' ends.Which of the following describes the genome ends?

Accepted Answer

The hepatitis B virus genome within the virion is partially double-stranded DNA, and it has unusual structures at its ends: the 5' end of the DNA has a protein attached (the viral polymerase), and the 3' end has a fragment of RNA, which is a remnant of the primer used for DNA synthesis.

Question 3

Which of the following mechanisms is used by hepatitis B to get the viral genome packaged into the virion?

Accepted Answer

The hepatitis B virus (HBV) uses its polymerase to interact with the pregenomic RNA (pgRNA) and the capsid protein. This interaction is crucial for the encapsidation of the pgRNA and the reverse transcription process that occurs within the capsid, leading to the formation of the viral DNA genome.

Question 4

Which of the following explains why there is a gap in the DNA genome of hepatitis B virus?

Accepted Answer

The answer of Which of the following explains why there...

Question 5

The longest open reading frame in the genome of hepatitis B virus genome encodes which of the proteins?

Accepted Answer

The answer of The longest open reading frame in the...

Question 6

The early steps of hepatitis B virus replication in an infected cell are poorly understood.Which of the following explains why?

Accepted Answer

The lack of cultured cells that can be productively infected with the virus is the main reason why the early steps of hepatitis B virus replication in an infected cell are poorly understood. This limits the ability to conduct experiments to study the interaction between the virus and the host cell machinery.

Question 7

It is recommended that people in certain professions or with certain disease should receive the hepatitis B vaccine.For which of the following individuals would it NOT be critical for them to be vaccinated against hepatitis B?

Accepted Answer

The answer of It is recommended that people in certain...

Question 8

The membrane binding domain for all three surface antigens from hepatitis B virus is located at which of the following locations?

Accepted Answer

The membrane binding domain for all three surface antigens from hepatitis B virus is located in the common C terminal domain, which is the small surface protein domain. This domain contains a hydrophobic sequence that anchors the protein in the membrane.

Question 9

A new method of preventing transmission of hepatitis B virus,called immunoprophylaxis,is described by which of the following statements?

Accepted Answer

Immunoprophylaxis involves the injection of specific antibodies to prevent infection. In this case, the injection of anti-hepatitis B antibodies into newborns can prevent transmission of the virus from infected mothers to their babies during childbirth. This method is called passive immunization, as the newborns receive pre-formed antibodies rather than making them on their own. A vaccine, as described in choice A, would stimulate the production of antibodies but is not a form of immunoprophylaxis. Choices B and C are focused on treating existing infections rather than preventing transmission. Choice E involves the use of interferon to treat existing infections and does not describe immunoprophylaxis.

Question 10

The drug Lamivudine (3TC)has been shown to inhibit which step in the infectious cycle of hepatitis B virus?

Accepted Answer

Lamivudine (3TC) is a nucleoside analog that inhibits the reverse transcription of the viral genome in hepatitis B virus, thereby preventing the virus from replicating its DNA.

Question 11

All of the following describe similarities between the reverse transcription process in retroviruses and hepadnaviruses EXCEPT:

Accepted Answer

The answer of All of the following describe similarities between...

Question 12

Which of the following mechanisms prevents packaging of the preC mRNA into the virion of hepatitis B virus?

Accepted Answer

The answer of Which of the following mechanisms prevents packaging...

Question 13

Which of the following occurs immediately after entry of the hepatitis B virus genome into the host cell?

Accepted Answer

The answer of Which of the following occurs immediately after...

Question 14

Like retroviruses,hepatitis B virus (HBV)uses a reverse transcription step.Which of the following distinguishes HBV from the retroviruses?

Accepted Answer

Retroviruses package RNA genomes in their virions, which are then reverse transcribed into DNA upon infection of a host cell. In contrast, HBV packages a partially double-stranded DNA genome in its virion, which is then delivered to the host cell upon infection. HBV also has an enveloped virion and can fuse its envelope with the host cell membrane, but these characteristics are not unique to HBV and are also shared with some retroviruses. HBV does not package reverse transcriptase in its virion, as this enzyme is encoded by the retroviral genome and is necessary for reverse transcription of the viral RNA genome into DNA.

Question 15

Hepatitis B virus produces both infectious and noninfectious particles.Only the infectious particles contain the large surface antigen.Which of the following explains why?

Accepted Answer

Only the large surface antigen interacts with the core protein, which is essential for the formation of infectious hepatitis B virus particles. This interaction is crucial for the virus's ability to assemble and release infectious particles, distinguishing them from the noninfectious ones that lack this specific antigen-core protein interaction.

Question 16

Which of the following describes the control sequences that hepatitis B viruses uses to direct transcription and processing of the viral mRNAs?

Accepted Answer

The answer of Which of the following describes the control...

Question 17

The hepatitis B genome as it is found inside the virion has an unusual structure.Which of the following is NOT a characteristic of the virion genome?

Accepted Answer

The hepatitis B virus genome does not have inverted repeats at each end; instead, it is partially double-stranded with a gap in the single-stranded region, a piece of RNA attached, a shorter plus strand compared to the minus strand, and a protein covalently attached to the 5' end.

Question 18

Which of the following describes an interesting feature of the preC and pregenomic mRNAs produced by the hepatitis B virus?

Accepted Answer

ED) Hepatitis B virus (HBV) mRNAs, including preC and pregenomic RNAs, are known to be transcribed past a polyadenylation signal near the promoter, which is a unique feature contributing to their regulation and processing.E) The preC and pregenomic mRNAs of HBV can indeed code for several proteins due to the use of alternative start codons. This allows the virus to produce multiple proteins from the same mRNA transcript, a strategy that maximizes the coding potential of the viral genome.

Question 19

Hepatitis B is usually transmitted via the oral-fecal route.

Accepted Answer

Hepatitis B is mainly transmitted through blood and bodily fluids, such as semen and vaginal secretions, and from mother to baby during childbirth. It can also be spread through sharing needles and other injection equipment, as well as through sexual contact.

Question 20

Scientists have generated mice that synthesize the X protein from hepatitis B virus in all of the liver cells.Which of the following describes the effect of the X protein on mice?

Accepted Answer

The X protein from hepatitis B virus has been shown to have oncogenic properties and can lead to the development of liver cancer. Therefore, the mice that synthesize the X protein in all of their liver cells are predisposed to developing liver cancer.

Quiz 30: Hepadnaviruses