Viruses cannot be cultured in media like, bacteria, but in a living cells.
Explanation:
In order to identify a virus the following techniques are performed: PCR (single round) or nested/semi-nested PCR, real-time PCR, direct electronic microscopy, antigen capture, isolation (gold standard for viruses that can be cultured). Viruses cannot be cultured in media like, bacteria, but in a living cells.
Virus culture is based upon amplification of potentially infectious pathogens. Implies intracellular replication of viruses in the cytoplasm or in the nucleus. It is controlled by regulations (i.e. bio-safety level 2, 3 or 4). It is possible to identificate and further investigate for pathogenicity, and antiviral sensitivity.
The primary cell culture is developed directly from living tissue and contain several different kinds of cells. They are expensive as they cannot be subcultured (passaged) more than a few times and hence new tissue needs to be obtained from animals on a regular basis. One example of a primary cell line is chicken embryo fibroblasts.
Diploid cell lines can be subcultured about 100 times before they die. Much more useful in the laboratory and they can be stored indefinitely in liquid nitrogen. An example of this type is human embryonic fibroblasts.
Continuous cell lines have lost the normal constraints on cell growth such as contact inhibition and mortality. They can be subcultured indefinitely in vitro. They are Hep-2, HeLa (from human cancers) and VERO (from Green African monkey kidney).
In order to obtain suitable specimens it is necessary to identify specimens with suitable information and to evaluate the success percent of the process. Transport attributes are 4⁰C,-20⁰C, dry ice (-79⁰C). According to the protocol, in vitro/in vivo cell cultures are used. There are blood specimens, stool, throat swabs, naso-pharyngeal aspirat, urine, saliva and biopsy of certain areas.
Virus detection may be non specific (cytopathogenic effect – microscope) or specific (immunological detection – antigen detection, PCR etc.).
Viral load estimation I performed by titration and/or plaque assay.
The most common culture limitations are the absence of detection system for the agent, inappropriate culture systems, viruses that cannot be cultured, a negative viral culture results does not mean that the agent is absent (PCR).
