Why can viruses of the family of the Poxviridae be genetically modified more easily than viruses of most other viral families?
A. Because their genome is smaller.
B. Because their genome is made of DNA.
C. Because their genome mutates more slowly.
D. Because their genomes have been sequenced.
<<Certain characteristics make poxviruses suitable for use as vaccine vectors. Importantly, these vectors are very stable and, when lyophilized, they can be refrigerated and used even after 2 months. They are easy to manufacture at a low cost and, furthermore, have the potential to be administered by different routes, as shown by their safe delivery by the intradermal, intranasal, intral, and intrarectal routes to generate antibody and T-cell responses. Oral administration of vaccinia recombinants has been shown to generate both mucosal and systemic immune responses to the recombinant protein. Finally, preexisting immunity to vaccinia virus, one of the main disadvantages of recombinant-viral vaccines, can be overcome by mucosal vaccination with vaccinia vectors due to compartmentalization of systemic and mucosal immune systems. Vaccinia induces a long-lasting immunity after a single immunization consisting of both humoral and cellular immune responses. Last but not least, one of the main features of this vector that gives it a tremendous advantage over other viral vectors is that large inserts of foreign DNA can be cloned into it, which allows for the insertion of multiple genes and the creation of multivalent vaccines. In a comparative study of several recombinant vectors for HIV vaccines, vaccinia vectors containing more than 10 kb of transgenic DNA have been used in trials, whereas other vectors such as adenoviral vectors can only accept less than 5 kb of genetic material (4). The possibility of introducing large amounts of DNA without disrupting viral stability allows for the insertion of several antigens even from different pathogens in the same recombinant vector, as has been shown with the insertion of the hepatitis B virus surface antigen, the herpes simplex virus glycoprotein D and the influenza virus hemagglutinin in the same vaccinia vector that generated an immune response to all three transgenic proteins upon injection in rabbits (5). >>http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005000400004
so, D, C, and B are true. However, in vaccines, stability is important, so I would go with C.
The correct answer is B. Because their genome is made of DNA.
Viruses of the family Poxviridae can be genetically modified more easily than viruses of most other viral families because their genome is made of DNA. DNA-based viruses are generally more amenable to genetic modification compared to RNA-based viruses.
To understand why, we need to consider the fundamental differences between DNA and RNA. DNA is a double-stranded molecule that is more stable compared to RNA, which is single-stranded. DNA is also a more accurate replicator, meaning it is less prone to errors during replication compared to RNA.
Due to these qualities, DNA-based viruses like the Poxviruses can be manipulated more effectively in the laboratory. Scientists can introduce specific genetic modifications into the DNA genome of the Poxvirus using techniques such as recombinant DNA technology. This allows them to add, delete, or alter specific genes within the virus, which can be used for various purposes such as developing vaccines or studying disease mechanisms.
On the other hand, RNA-based viruses are more prone to genetic instability and have a higher mutation rate, making them more difficult to genetically manipulate. Their genetic material is more prone to errors during replication, and even minor changes in their genetic sequence can result in significant changes in their characteristics and behavior. This makes it more challenging to precisely modify their genome without unintentionally affecting essential functions or causing unintended consequences.