Janet, The NIH recombinant guidelines apply to the use of retroviral vectors as DNA elements, not to the cells that have been infected using the retroviral vectors. I agree with Dr. Jacobberg that the most readily identified hazard is that the packaging cell line (the final cell used to produce infectious particles) is not really helper free; i.e., that it does not contain another virus that can be activated to produce a replication competent virus that would be infectious. There are two examples of such helper virus rescue in the last two years, each of which led to the isolation of a previously unknown endogenous retrovirus in the "helper free" packaging cell line. We, and most other labs I know about using retrovirus vectors, always use them at BSL-2 level. Even the risk of rescue of a replication competent virus is remote, the low risk is real and it is only prudent to adopt the safer standard. There is still no evidence that retroviruses can be spread by aerosols, so containment of aerosols in a sorting environment is probably more important for other potential human pathogens. >The NIH recombinant guidelines indicates the mouse retroviral vectors can be >used at BSL-1. > >The quote is as follows: > > >Appendix B-V-1. Murine Retroviral Vectors > >Murine retroviral vectors to be used for human transfer experiments (less >than 10 liters) that >contain less than 50% of their respective parental viral genome and that >have been demonstrated to >be free of detectable replication competent retrovirus can be maintained, >handled, and >administered, under BL1 containment. > > The URL is: http://www.orcbs.msu.edu/biological/NIH/appendixb.htm > > >> -----Original Message----- >> From: Rice, Susan E. (Fka Grigsb [SMTP:srice1@iupui.edu] >> Sent: Tuesday, January 26, 1999 12:36 PM >> To: Cytometry Mailing List >> Subject: Retroviral vectors >> >> >> Dear Flow Group, >> >> Could someone please bring me up to speed on sorting human cells infected >> with retrovirus which are used for research purposes? I understand that >> these reagents are supposed to be defective viruses used for genetic >> transfer. What biohazard classification has a laboratory working with >> these >> vectors? What precautions over and above the common practices are >> required? >> Will bleaching through the sample probe between sorts eliminate viruses >> from >> the flow cytometer to prevent viral contamination of subsequent sorts? >> >> Please cite references if available. Can someone cite a reference that >> lists the requirements for laboratories according to the different >> biohazard >> classifications? >> >> Thanks in advance, >> Sue Rice >> ______________________________________________________________________________ Donald E. Mosier, Ph.D., M.D. Department of Immunology IMM7 The Scripps Research Institute 10550 N. Torrey Pines Road La Jolla, CA 92037 619 784-9121 voice 619 784-9190 fax
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