http://www.ncbi.nlm.nih.gov/pubmed/20378372 I've been reading up on these retroviruses... they can swap information if they coinfect a cell... in fact thats how labs swap pieces of these viruses around in labs.... so basically if you have a whole bunch of retroviruses being mushed around they share bits and pieces and who knows what you're gonna get I read that there have been issues in zoos even where endogenous retroviruses from one species infected those at another fun times Endogenous retroviruses as potential hazards for vaccines. Miyazawa T. Laboratory of Signal Transduction, Department of Cell Biology, Institute for Virus Research, Kyoto University, 53 Shogoin-Kawaracho, Sakyo-ku, Kyoto 606-8507, Japan. email@example.com Abstract Retroviruses are classified as exogenous or endogenous according to their mode of transmission. Generally, endogenous retroviruses (ERVs) are not pathogenic in their original hosts; however, some ERVs induce diseases. In humans, a novel gammaretrovirus was discovered in patients with prostate cancer or chronic fatigue syndrome. This virus was closely related to xenotropic murine leukemia virus (X-MLV) and designated as xenotropic murine leukemia virus-related virus (XMRV). The origin and transmission route of XMRV are still unknown at present; however, XMRV may be derived from ERVs of rodents because X-MLVs are ERVs of inbred and wild mice. Many live attenuated vaccines for animals are manufactured by using cell lines from animals, which are known to produce infectious ERVs; however, the risks of infection by ERVs from xenospecies through vaccination have been ignored. This brief review gives an overview of ERVs in cats, the potential risks of ERV infection by vaccination, the biological characteristics of RD-114 virus (a feline ERV), which possibly contaminates vaccines for companion animals, and the methods for detection of infectious RD-114 virus. 2010 The International Association for Biologicals. Published by Elsevier Ltd. All rights reserved. Transspecies Transmission of the Endogenous Koala Retrovirus Uwe Fiebig,1 Manuel Garcia Hartmann,2 Norbert Bannert,1 Reinhard Kurth,1 and Joachim Denner1* Robert Koch Institute, 13353 Berlin,1 and Zoo Duisburg, 47058 Duisburg,2 Germany Received 16 December 2005/Accepted 8 March 2006 The koala retrovirus (KoRV) is a gammaretrovirus closely related to the gibbon ape leukemia virus and induces leukemias and immune deficiencies associated with opportunistic infections, such as chlamydiosis. Here we characterize a KoRV newly isolated from an animal in a German zoo and show infection of human and rat cell lines in vitro and of rats in vivo, using immunological and PCR methods for virus detection. The KoRV transmembrane envelope protein (p15E) was cloned and expressed, and p15E-specific neutralizing antibodies able to prevent virus infection in vitro were developed. Finally, evidence for immunosuppressive properties of the KoRV was obtained. Virology. 2010 Jul 6. [Epub ahead of print] The complete genome and genetic characteristics of SRV-4 isolated from cynomolgus monkeys (Macaca fascicularis). Zao CL, Armstrong K, Tomanek L, Cooke A, Berger R, Estep JS, Marx PA, Trask JS, Smith DG, Yee JL, Lerche NW. VRL Laboratories, San Antonio, TX 78229, USA. Abstract At least 5 serotypes of exogenous simian retrovirus type D (SRV/D) have been found in nonhuman primates, but only SRV-1, 2 and 3 have been completely sequenced. SRV-4 was recovered once from cynomolgus macaques in California in 1984, but its genome sequences are unknown. Here we report the second identification of SRV-4 and its complete genome from infected cynomolgus macaques with Indochinese and Indonesian/Indochinese mixed ancestry. Phylogenetic analysis demonstrated that SRV-4 was distantly related to SRV-1, 2, 3, 5, 6 and 7. SRV/D-T, a new SRV/D recovered in 2005 from cynomolgus monkeys at Tsukuba Primate Center in Japan, clustered with the SRV-4 isolates from California and Texas and was shown to be another occurrence of SRV-4 infection. The repeated occurrence of SRV-4 in cynomolgus monkeys in different areas of the world and across 25years suggests that this species is the natural host of SRV-4. Copyright 2010 Elsevier Inc. All rights reserved. Soooo..... what animal parts do we use in human vaccines???? Isn't this the CDC's territory?