Block 9 Micro Viral Replication Prt 1

The virion structure indicated by the arrow is the capsid. The capsid is the protein coat that surrounds the genetic material of a virus. It provides protection for the genetic material and helps in the attachment of the virus to host cells. The capsid is made up of repeating protein subunits called capsomeres, which come together to form the overall structure of the capsid.

The function of the structure identified in question 2 is to protect the genomic cargo.

RNA-dependent RNA polymerase is the correct answer because (-) ssRNA viruses have a single-stranded RNA genome that cannot be directly used as a template for replication. RNA-dependent RNA polymerase is the enzyme that is responsible for synthesizing a complementary RNA strand based on the viral RNA template. This enzyme is essential for the replication of (-) ssRNA viruses. DNA-dependent RNA polymerase is not involved in the replication of RNA viruses, and RNA-dependent DNA polymerase is not relevant to (-) ssRNA viruses. DNA-dependent DNA polymerase is involved in DNA replication, not RNA replication. Reverse transcriptase is an enzyme that is specific to retroviruses and is not required for the replication of (-) ssRNA viruses.

The composite virus engineered by the virology research lab contains Rhinovirus type 99 RNA. Therefore, if this virion were to infect permissive cells, it would generate Rhinovirus type 99.

The correct answer is "Host cell possesses the proper receptor(s) required for viral binding." This means that the host cell has the specific receptors on its surface that can bind to the viral particles and allow them to enter the cell. Without these receptors, the virus would not be able to infect the cell.

Maraviroc, as a chemokine receptor antagonist, binds to the human chemokine receptor CCR5. This receptor plays a crucial role in the entry of Human immunodeficiency virus type 1 (HIV-1) into host cells. By binding to CCR5, Maraviroc prevents the virus from attaching to and entering the host cells, thereby inhibiting the initial step of the viral replication cycle, which is the entry of HIV-1 into the host cells.

The capsid is the outer protein shell of a virus that protects its genetic material. It plays a crucial role in determining cell susceptibility because it is responsible for attaching to specific receptors on the surface of host cells. The capsid allows the virus to enter the host cell and deliver its genetic material, initiating the infection process. Therefore, the presence and structure of the capsid are essential factors in determining whether a cell is susceptible to a particular virus.

DNA-dependent DNA polymerase is the enzyme required for the replication of dsDNA viruses. This enzyme is responsible for synthesizing new strands of DNA using a template strand of DNA. It catalyzes the addition of nucleotides to the growing DNA chain, creating a complementary copy of the viral DNA. This process is essential for the replication and propagation of dsDNA viruses.

If the virus had been naked, the structure identified in question 2 would have served the function of protecting the genomic cargo and binding to the cell. This means that the structure would have acted as a shield for the genetic material of the virus and also facilitated the attachment of the virus to the host cell.

That would have to be a naked, (+) ssRNA virus, such as the Picornaviridae, Caliciviridae, Astroviridae and Hepeviridae, as well as some naked, DNA viruses such as papillomaviruses and polyomaviruses.

The correct answer is "Cellular DNA-dependent RNA polymerase and reverse transcriptase." Hepatitis B virus (HBV) is a gapped DNA virus that infects humans. In order to complete its replicative cycle, HBV requires the use of cellular DNA-dependent RNA polymerase and reverse transcriptase enzymes. These enzymes are responsible for transcribing the viral DNA into RNA and then reverse transcribing the RNA back into DNA, allowing for the replication of the virus.

“A” could be exceptionally, borderline, right, but “B” is by far more common. “D” corresponds to coordinated assembly.

Retroviruses such as HIV-1 require viral RNA-dependent DNA polymerase to convert their RNA genome into DNA, which is an essential step in their replication cycle. Additionally, they also require cellular DNA-dependent RNA polymerase to transcribe the newly formed DNA into RNA, which can then be used for protein synthesis. Therefore, the correct answer is "Viral RNA-dependent DNA polymerase and cellular DNA-dependent RNA polymerase."

Viral packaging refers to the process of incorporating the genomic nucleic acid into the capsid. This process typically occurs after capsid formation. Therefore, the assertion that viral packaging can be done prior to capsid formation is false.

If a non-vaccinated laboratory technician accidentally infects themselves with a liquid suspension of Ebola virus, the outcome would be no viral replication and no disease. This is because the technician's immune system would recognize the virus as foreign and mount an immune response to eliminate it before it can replicate and cause disease. Without viral replication, the individual would not develop any symptoms or illness associated with Ebola virus infection.

One could argue that “C” is also a right answer, and this would be right; but “D” is a better answer because it is more inclusive. For those wondering why “E” is wrong, virions are infectious viruses by definition hence the maturation process has already occurred (maturation often being dependent on viral proteolytic activity such as HIV’s protease or influenza’s neuraminidase).

If a non-vaccinated laboratory technician accidentally infects themselves with a liquid suspension of Measles virus, the outcome would be both viral replication and disease. This is because the Measles virus is capable of replicating in the body and causing an infection, leading to the development of symptoms and disease. The technician's lack of vaccination would leave them susceptible to the virus, allowing it to replicate and cause illness. Therefore, options A and B are both correct.

The correct answer is (+) ssRNA & capsid. This is because the progeny virus is a positive single-stranded RNA virus, which means it has a single-stranded RNA genome. The capsid is the protein coat that surrounds and protects the viral genome. Therefore, the composition of the progeny virus would include the positive single-stranded RNA genome and the capsid.

The G protein is the viral element that would determine cell susceptibility. The G protein is responsible for binding to specific receptors on the surface of host cells, allowing the virus to enter and infect the cell. The presence or absence of the G protein on the virus determines which cells it can attach to and infect, making it a crucial factor in determining cell susceptibility.

“C” and “E” could also be correct under some circumstances; “C” could represent the case of HIV whereas “E” could represent the case of HBV. This being said, I would expect most of you to answer “A” because it is the one presented in your material as the default one and we haven’t gone through specific viruses at this point