Simulation and prevention of retrovirus--specific reactions by mycoplasmas

Sourcing and using stem cell lines for radiation research: Potential, challenges and good stem cell culture practice

PURPOSE

Exposition of best practice in management and experimental use of human stem cell lines in radiobiological research. This paper outlines the key challenges to be addressed by radiobiologists wishing to use human pluripotent stem cell (hPSC) lines in their research including human embryonic stem cell (hESC) lines and human induced pluirpotency stem (hiPSC) lines. It emphasises the importance of guidance already established for cell culture in general and outlines some further considerations specific to the culture of human pluripotent stem cell lines which may impact on the interpretation of data from radiobiological studies using these cells. Fundamental standards include obtaining cells from bona fide suppliers with suitable quality controls, screening cell lines to ensure absence of mycoplasma and authentication of cell lines by DNA profiling. For hESC and hiPSC lines, it is particularly important to recognise the significance of phenotypic and genetic stability and this paper will address approaches to reduce their impact. Quality assured banking of these two types of stem cell lines will facilitate reliable supply of quality controlled cells that can provide standardisation between laboratories and in the same laboratory over time.

CONCLUSIONS

hPSC lines could play an important role in future radiobiological research providing certain fundamental principles of good stem cell culture practice are adopted at the outset of such work.

Cell culture contamination

Microbial contamination is a major issue in cell culture, but there are a range of procedures which can be adopted to prevent or eliminate contamination. Contamination may arise from the operator and the laboratory environment, from other cells used in the laboratory, and from reagents. Some infections may present a risk to laboratory workers: containment and aseptic technique are the key defence against such risks. Remedial management of suspected infection may simply mean discarding a single potentially infected culture. However, if a more widespread problem is identified, then all contaminated cultures and associated unused media that have been opened during this period should be discarded, equipment should be inspected and cleaned, cell culture operations reviewed, and isolation from other laboratories instituted until the problem is solved. Attention to training of staff, laboratory layout, appropriate use of quarantine for new cultures or cell lines, cleaning and maintenance, and quality control are important factors in preventing contamination in cell culture laboratories.

Antiretroviral antibodies: implications for schizophrenia, schizophrenia spectrum disorders, and bipolar disorder

BACKGROUND

Some retroviral antigens share structural homology within a group of related retroviruses. It is possible that antibodies directed against one virus may cross-react with antigens from a different virus in the group.

METHODS

Using this principle, the human immunodeficiency virus 1 (HIV-1) Western blot assay was used as an available source of human retroviral antigens to screen serum samples from an archived collection to ascertain whether there was an association between serum antiretroviral antibodies and mental illnesses.

RESULTS

A statistically significant proportion (28/54, 52%) of patients suffering from psychiatric disorders had serum antibodies that recognized at least one antigen present on the blot, culminating in indeterminate HIV-1 tests. The majority of the reactive samples were directed against the HIV-1 group antigens p24 and p17. These findings contrast with those of nonpsychiatric patients, who had 4/16 (25%) indeterminate blots.

CONCLUSIONS

The results suggest exposure to retroviral antigens related to those of HIV-1 in subpopulations of schizophrenic, schizophrenic spectrum disorder, and bipolar disorder patients.

Suppression of HIV-1 reverse transcriptase activity by mycoplasma contamination of cell cultures

The detection of HIV-1 in human peripheral blood lymphocytes is routinely carried out by cocultivation of test cells with normal peripheral blood mononuclear cells (PBMC). The presence of virus is evidenced by cytologic observation of syncytia or by detecting viral reverse transcriptase (RT) and/or p24 antigen in the culture supernatant fluid. Syncytia formation is almost always associated with the presence of virus as measured by RT, although many RT-positive cultures do not form syncytia. As part of a large screening program, we identified three cultures that showed syncytia but were RT negative. The basis for these discrepant observations was contamination of cultures with mycoplasma that interfered with the RT assay and thereby obscured virus detection. Treatment of cultures with BM-cycline removed mycoplasma contamination and restored RT activity. The present findings indicate the need for caution in the interpretation of negative RT results during HIV-1 isolation and especially in cultures that show evidence of syncytia formation.

Further evidence for a retrovirus as the aetiological agent of sheep pulmonary adenomatosis (jaagsiekte)

The infective agent of jaagsiekte was shown to be present in the fluid which accumulates in the respiratory tract of sheep during the terminal stages of the disease. The fluid also contained reverse transcriptase (RT) activity which showed a clear preference for a ribonucleic acid synthetic template over the corresponding deoxyribonucleic acid template and which utilised the RT specific template/primer poly (2'-0-methylcytidylate) oligodeoxyguanylate. This enzyme activity was associated with a particle which had typical retroviral buoyant densities in a range of gradient media.