J Hepatol. Anal Biochem. J Virol Methods. Quantitative detection of hepatitis C virus RNA with a solid-phase signal amplification method: definition of optimal conditions for specimen collection and clinical application in interferon-treated patients. The stability of serum hepatitis C viral RNA in various handling and storage conditions. Arch Pathol Lab Med. Impact of various handling and storage conditions on quantitative detection of hepatitis C virus RNA.
Am J Clin Pathol. The treatment of chronic viral hepatitis. N Engl J Med. Krajden, M. Minor, J. Zhao, O. Rifkin, and L.
Submitted for publication. Polymerase chain reaction assay for hepatitis C virus RNA using a single tube for reverse transcription and serial rounds of amplification with nested primer pairs. J Med Virol. Hepatitis C viral dynamics in vivo and the efficiency of interferon-alpha therapy. Viral dynamics in hepatitis B virus infection. High-performance liquid chromatography to assess the effect of serum storage conditions on the detection of hepatitis C virus by the polymerase chain reaction.
Sall J, Lehman A. JMP start statistics. Effects of anticoagulants and storage of blood samples on efficacy of the polymerase chain reaction assay for hepatitis C virus. Support Center Support Center. External link. It is resistant to most proteases and a variety of chemical treatments that would inactive many viruses. However, because it is so large, it has a large surface area and is more likely to stick to hydrophobic surfaces and aggregate than smaller proteins.
It can be useful to think of lentiviruses as small cells. They have a membrane and a small amount of cytoplasm. The capsid, which contains the genome, is somewhat like a nucleus.
As such, they are very unstable and should be treated gently like a cell would be. It can be useful to think of retroviruses as small cells. They have a membrane, a small amount of cytoplasm and the capsid containing the genome is somewhat like a nucleus. As such they are very unstable and should be treated gently like a cell would be.
Myths about viruses and viral vectors. Learn more about giving opportunities for the neurosciences at Stanford. Skip to content Skip to navigation. Wu Tsai Neurosciences Institute. Search form Search. Care and Handling of Viruses. AAV is more stable than many viruses or proteins and can be frozen and thawed several times with minimal loss of activity but it is best to avoid. Most AAVs are very sticky and losses can occur if they are exposed to regular plastics e.
The horizontal dashed line in each panel indicates the cutoff point, above which results represent seropositivity as established by the kit manufacturer. The significant P values do not appear to be caused by outliers, either within subjects or between subjects. Frozen serum banks are an important source of scientific and clinical information and are essential to infectious disease and vaccine research.
Although not well studied, repeated freeze-thaw cycles, at least theoretically, may damage the entity being measured. Previous studies have yielded inconsistent results. Other investigators have demonstrated that IgG antibodies to cytomegalovirus were unstable after more than 5 freeze-thaw cycles, leading to significant variability in antibody testing results J.
Helgason, M. Jones, A. Wold, and T. Smith, Abstr. C-3, p. We assume that this instability in the measured antibody activity level is a result of protein denaturation during the freeze-thaw cycle. Normally, in an aqueous environment, proteins fold spontaneously, so the hydrophobic side chains are encased by polar chains with a surrounding bulk hydration layer.
Freezing disrupts this bulk hydration layer, forming a crystal lattice of ice and rendering it inactive. Unfolding allows hydrophobic reactions to occur, thus denaturing the protein. Examination of the assay values does not suggest any consistent nonlinear trend, nor any threshold effect, such as a number of cycles beyond which the change in antibody levels is more rapid.
Direct comparison of baseline and final assay values showed no evidence for change in actual antibody level. However, the random-effects regression showed trends over a number of cycles.
Measles antibody levels showed an increasing trend, rubella virus antibody levels showed a decreasing trend, and mumps antibody levels remained constant. Because of the physical effect of freezing, all three assays should have a decreasing or similar trend. We believe that the trends observed are due to instrument drift in the assay and do not reflect changes in the samples, because the interassay coefficient of variation measured after nearly 2, measles assays with this kit was 6.
The changes observed were small, averaging less than 0. These changes have no apparent clinical significance, and there are no statistically significant differences between baseline and final i.
Thus, despite the small number of volunteers, the results are robust enough to demonstrate the lack of effect from the freeze-thaw cycles.
We recognize previous work inconsistently indicated potential deleterious effects, but the literature does not provide adequate methodology. While we found no evidence that freeze-thaw cycles might affect antibody measures, we did not examine antibody function. Furthermore, our enzyme-linked immunosorbent assay tested whole-virus antibody-antigen binding. The freeze-thaw cycle may interfere with different antibody-epitope binding sites.
Also, one must consider other factors that might destabilize antibody levels, such as length of storage, aliquot size, dilution, and temperature. We found no effect with MMR. We recommend those working with other antibodies consider similar testing. In conclusion, our study demonstrates that the IgG antibody activity levels measured for MMR with whole-virus EIAs are stable after 10 freeze-thaw cycles.
Although variations in the absolute values were obtained, the values were not clinically significant and did not reflect assay variability.
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