Question

Which method is used to culture viruses that attack only bacteria?

    I. a continuous or immortal cell line

II. a primary cell line

Group of answer choices

Neither I or II

Only I

Only II

Both I and II

Answer 1

Answer: Only I

Explaination:

A bacteriophage is a type of virus that infects bacteria. Viruses require a living host cell for replication. Infected host cells (eukaryotic or prokaryotic) can be cultured and grown, and then the growth medium can be harvested as a source of the virus. Virions in the liquid medium can be separated from the host cells by either centrifugation or filtration. Viruses can be grown in vivo (within a whole living organism, plant, or animal) or in vitro (outside a living organism in cells in an artificial environment, such as a test tube, cell culture flask, or agar plate). Bacteriophages can be grown in vivo in the presence of a dense layer of bacteria grown in a 0.7 % soft agar in a Petri dish or flat-bottom flask.

For in vitro studies primary cell culture and secondary cell culture are used. Primary cell culture is freshly prepared from animal organs or tissues in a petri dish or tissue-culture flask so that the cells have a solid surface such as glass or plastic for attachment and growth. Primary cultures usually have a limited life span. Cells from the primary cell culture must be transferred to another vessel with a fresh growth medium to prevent contact inhibition. This is called secondary cell culture. This transfer of growing cells from primary to secondary culture forms continuous cell lines that derive transformed cells. These transformed cells can be subcultured many times or even grown indefinitely. This is called the immortal cell line. An example of an immortal cell line is the HeLa cell line. This was originally cultivated from tumor cells obtained from Henrietta Lacks, a patient who died of cervical cancer in 1951. HeLa cells were the first continuous tissue culture cell line and were used to establish tissue culture as an important technology for research in cell biology, virology, and medicine.

Therefore the method used to culture viruses that attack only bacteria is a continuous or immortal cell line. So the correct answer is “Only I”