1) Using your basic knowledge of biology and a little research, generally describe how viruses infect cells. Are viruses alive?

2. In particular, please comment on the Zika virus being transmitted?

3. What types of cells does Zika virus infect? Which system do these infected cells belong to? Describe the role of affected cells in each of the systems.

5. Suggest a rapid test that can be done to detect Zika virus infection in symptomatic people, or find and describe a test currently available. Explain why you are offering this test.

1.) The 6-step general pathway of how viruses infect cells and replicate:

Attachment ---> Penetration ---> Uncoating ---> Replication ---> Assembly ---> Release

"Are viruses alive?" is already a long-standing debate within the scientific community due to the nature of how viruses operate and reproduce. Their nature of being dormant when outside of a host cell to being active when inside a host cell to replicate puts them in between the gray area of "living" and "non-living".

If based on the definition of the cell which is the smallest and most basic unit of life capable of replicating itself independently, then a virus is deemed to be non-living organism since it cannot replicate independently.

2.) Zika virus (ZIKV) is primarily transmitted effectively and conveniently through a vector (an organism serving as a transport service for the virus), particularly certain species of the Aedes mosquito. When the female mosquitoes feed, the virus is transmitted via the bite to the bloodstream. There are other lesser known modes of transmission for the virus such as blood transfusion of tainted blood, mother-to-infant, and sexual contact.

3.) ZIKV infects various human cells ranging from the ones found in the skin, blood, eyes, and even the brain. However, it is important to note that the virus targets cells like monocytes (a type of white blood cell) and dendritic cells. These particular cells work for the immune system to protect the body from foreign invaders.

Monocytes can engulf (phagocytosis) microorganisms/foreign matter and process them. They can also present antigens and even produce cytokines, small molecular signals of the immune system, to stimulate an immune system response. Dendritic cells are special immune cells which capture, process, and present antigens on their surface to T-cells.

5.) IgM or IgG Antibody testing could be done to detect on-going ZIKV infections in symptomatic patients. The test's mechanism of action is attaching specific antigens that react to ZIKV specific IgM/IgG antibodies to detect if there is present infection. A positive result would usually be a change in color or fluorescence depending on the test kit. This rapid test is relatively less costly than other tests (NAAT) due to scaling in production, less processing time, less equipment used, and convenient to use. Even with these advantages, there are certain limitations such as obtaining false-positive results and/or cross-reactivity to other viruses.