Which structure occurs in the genome of parvoviruses
a. Linear, single-stranded, segmented
b. Linear, single-stranded, non-segmented
c. Circular, double-stranded, non-segmented
d. Segmented, completely double-stranded
e. Circular, segmented
The correct answer and explanation is:
The correct answer is b. Linear, single-stranded, non-segmented.
Parvoviruses are small DNA viruses that have a relatively simple structure. Their genome is linear and consists of single-stranded DNA. This genome is non-segmented, meaning that it is one continuous piece of genetic material rather than being divided into separate segments. The virus’s small size and the simplicity of its genome distinguish it from more complex viruses.
The single-stranded DNA (ssDNA) of parvoviruses is typically around 5 kilobases in length, which is much smaller than the genomes of many other types of viruses. Once inside the host cell, the single-stranded DNA is converted into double-stranded DNA through a process involving the host’s DNA polymerase, which is essential for the replication of the virus.
These viruses usually infect dividing cells, as their replication relies on the host cell’s DNA machinery. After the genome is converted to double-stranded DNA, it is transcribed and replicated using the host’s polymerases. This step is crucial because parvoviruses do not encode the necessary machinery for DNA replication, thus depending on the host cell’s division cycle for their replication.
Parvoviruses are also known for their ability to cause diseases in animals and humans, including fifth disease in humans and canine parvovirus in dogs. The linear, single-stranded nature of their genome plays a role in the virus’s ability to infect and replicate inside host cells efficiently. Parvoviruses are relatively simple compared to other DNA viruses, yet they are still capable of causing significant disease.
In summary, parvoviruses have a linear, single-stranded, non-segmented genome, which is characteristic of this group of viruses.