Biotechnology and Bioinformatics (1+1)

3.1.11. 1. Isolation and identification of fish viruses

The first cell line (RTG–2) was developed from trout and used to facilitate the isolation of infectious pancreatic necrosis virus (1PNV) by Wolf and Quimby (1962). There has been a rapid increase in the number of continuous cell cultures from carp, loach, tilapia, perch, milkfish, grouper, snakehead, seabream, and eels. These new cell lines are being used to isolate previously undetected and unknown viruses and for comparative studies of these viruses.

2. Fish cell cultures are very useful in in vitro models for studying the replication and genetics of viruses, the effects of antiviral drugs, and the production of experimental vaccines.

3. Fish cells have been utilised for determining karyotypes and other aspects of cytogenetics such as chromosomal polymorphism and speciation, chromosomal abnormalities and evolution.

4. Organ cultures of pituitary glands derived from tilapia, and monolayer pituitary cell cultures from tilapia, rainbow trout have been used to study the production of the growth hormone prolactin. Also, pituitary organ cultures from rainbow trout and cell culture from trout, carp and gold fish have been employed as in vitro systems for studying the mechanism of production and regulation of gonadotropin.

5. Cultured kidney tissue has been useful in comparing testosterone–dependent changes in vivo and in vitro in the structure of the renal glomeruli of teleost fishes.

6. Gonadal cell and organ cultures have contributed to studies on the effects of testosterone on spermatogenesis, endocrine activities of isolated folicular cells, and function of selected enzymes in the steroid negative–feedback regulation of gonadotropic hormone release.

7. Increasing use is being made of fish cell cultures in the field of toxicology, both as in vitro systems for studying the metabolism of various toxicants and as sensitive indicator models for testing the cytotoxic ity of aquatic pollutants.

8. Both primary cultures and established cell lines are also sensitive and can be used in assay systems for screening aquatic pollutants for cytotoxicity.

9. Fish cell cultures have been utilized for more detailed investigations of the processes leading to the proliferation and differentiation of tumours and tumour cells. Fish cell cultures are also used for testing and evaluating the effects of carcinogens such as the use of primary cultures of fish hepatocytes for investigating carcinogenic effects of dimethylnitrosamine, aflatoxin B1, benzo(a)pyrene, and N-methyl-N’-nitro-N-nitrosoguanidine.

10. Cell and organ cultures have facilitated studies of the immune response in fish. Cell cultures were also used to gain a better understanding of how fish macrophages and lymphocytes differentiate and function in the immune response. In vitro systems have been used to study the effects of various substances such as antibiotic s on the modulation of cells of the immune system as well as the function and comparative phylogenetics of various lymphokines such as interleukin 1. In vitro systems have been particularly useful in studying both antigen–specific and nonspecific cell-mediated immunity.

In vitro techniques to detect antibody –producing cells (plaque–forming cells, PFC and antigen–binding cells (rosette–forming cells, RFC) can be used to monitor the immune response in fish immunized with vaccines for bacterial pathogens.