Passage

Passage
Viruses are known as obligate intracellular parasites because they cannot reproduce independently (outside of a host cell) .  Viral genomes (RNA or DNA) are enclosed by a protein shell known as the capsid.  Some viruses, known as enveloped viruses, have an additional phospholipid bilayer that fully envelops the capsid.  Viruses that lack this outermost phospholipid covering are labeled non-enveloped.  The entry of either enveloped or nonenveloped viruses into a host cell enables the production of viral proteins and the subsequent assembly of viral progeny.Immune cells (B and T cells) protect host organisms against viral infections by recognizing viral particles (antigens) as foreign.  In response to the recognition of foreign particles, antigen-presenting cells display cleaved antigens (also known as antigen fragments) on their surface, which enable the activation of other immune cells that stimulate an immune response, including the production of neutralizing antibodies.An example of an infectious disease is viral hepatitis (inflammation of the liver) , which can be caused by any one of five distinct hepatitis viruses (A-E) that infect hepatocytes (liver cells) .  HAV, HCV, and HEV contain positive-sense, single-stranded RNA (+ssRNA) as genetic material.  In contrast, HBV has a partially double-stranded circular DNA genome.  HDV is unique because it has a negative-sense, single-stranded RNA (−ssRNA) genome.Researchers hypothesized that synthetic antibodies could be used to treat viral hepatitis in patients with compromised immune systems.  Fluorescent antibodies, designed to bind the capsid proteins of the five hepatitis viruses, were added to separate wells containing each type of virus.  The fluorescence assay that was performed detected only bound antibodies in media with HAV or HEV.
Adapted from Shin EC, Sung PS, Park SH. Immune responses and immunopathology in acute and chronic viral hepatitis. Nat Rev Immunol. 2016;16(8) :509-23.
-Assume bacteria are infected with a vector containing HBV genetic material.  This vector has been shown to introduce its genomic content into bacterial cells without fully gaining entry into the bacterial cytoplasm.  Based on this information, the vector is most likely a:

A) prion.
B) bacterium.
C) viroid.
D) bacteriophage.

Correct Answer:

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