The paper below shows that vaccines cultured in chick embryos (such as measles and mumps) contain "retroviruses" that show potential for replicating (and causing cancer) in the host (human). Researchers have detected "reverse transcriptase" activity in vaccines. Reverse transcriptase is a DNA polymerase enzyme that transcribes single-stranded RNA into double-stranded DNA. This is not new news. It was known well over ten years ago, but organisations such as WHO, after confirming the findings, have just let this issue go down quietly.

Now you may have thought that all that is in a vaccine is the actual virus itself (measles, mumps etc.) in a totally sterile (clean, pure) environment along with a few other things (preservatives and adjuvants) and that its it. Well you are wrong. These vaccines are cultured in cells of animals (such as chickens, monkeys, calves, humans, and aborted fetuses) - these are called substrates - and genetic material, proteins etc. from these substrates remains in the vaccine. So your vaccine is not sterile and pure, it actually contains hundreds of small particles and viruses - and the vaccine researchers and safety specialists know this, and they don't know exactly what things are in there. They can only test for things that they already know are harmful particles, which means that they have no idea about whatever else is in there.

Maudru T, Peden KW. Laboratory of Retrovirus Research, Food and Drug Administration, Bethesda, MD 20892, USA. Analysis of a coded panel of licensed vaccines by polymerase chain reaction-based reverse transcriptase assays: a collaborative study.Clin Virol. 1998 Jul 24;11(1):19-28.

BACKGROUND: A recent publication reporting the presence of low levels of reverse transcriptase (RT) activity in certain vaccines for human use necessitated that regulatory agencies address the issue of whether this RT activity presented a risk to humans. Detection of low levels of RT activity corresponding to fewer than ten virions became possible with the development of highly-sensitive polymerase chain reaction (PCR)-based RT (PBRT) assays. Variations of the PBRT assay were developed in three laboratories. These assays were reported as being at least one million-fold more sensitive than conventional RT assays. OBJECTIVE: To ascertain the sensitivity and reliability of PBRT assays in different laboratories and to determine which vaccine samples possessed RT activity. STUDY DESIGN: Coded panels of licensed vaccines together with positive and negative controls was assembled at the Center for Biologics Evaluation and Research (CBER) of the Food and Drug Administration (FDA) and distributed to five cooperating laboratories as well as to our laboratory at CBER. Each laboratory carried out their version of the PBRT assay and submitted the results to the coordinator at CBER. RESULTS: Results of the PBRT analyses carried out in the six laboratories are presented. Five of the six laboratories reported results that were highly consistent. RT activity was detected in live attenuated vaccines that were prepared in chick embryo cells (mumps, measles and yellow fever), but very low or undetectable RT activity was found in vaccines produced in mammalian cells (rabies and rubella). influenza vaccines from several manufacturers included in the panel displayed the most variability, with different products of this inactivated vaccine having differing amounts of RT activity. CONCLUSIONS: Only vaccines produced in chick embryo cells had significant RT activity. Because RT activity was present in the allantoic fluid of uninfected chick embryos and culture medium from chick embryo fibroblasts, the RT activity arises from the cell substrate used for vaccine production. The PBRT assays were reliably able to detect the low levels of RT activity in chicken-derived vaccines.

Another paper involving the measles vaccine component:

R N Weissmahr, J Schüpbach, and J Böni. Swiss National Center for retroviruses, University of Zurich. Reverse transcriptase activity in chicken embryo fibroblast culture supernatants is associated with particles containing endogenous avian retrovirus EAV-0 RNA. J Virol. 1997 April; 71(4): 30053012.

We have recently shown that live attenuated virus vaccines produced on chicken-derived cells contain low levels of particle-associated reverse transcriptase (RT). In both virus and corresponding control harvests produced on chicken embryo fibroblasts, these activities were present at significantly higher concentrations than in the vaccines. In order to identify the putative retrovirus sequence responsible for this activity, a novel method for the selective PCR amplification of particle-associated retrovirus RNA that uses DNA primers complementary to the primer binding sites of the known exogenous retroviruses in combination with an anchor primer was applied. A product of the endogenous avian retrovirus family EAV-0, termed EAV-0(B1), was reproducibly generated with a tRNA(Trp)-derived primer from the RT peak fraction of a sucrose density gradient run with a harvest of a live attenuated measles vaccine. In contrast, no products were detected with primers derived from tRNA(Pro), tRNA(Lys)1,2 or tRNA(Lys)3. In the same fraction, genomic RNA of EAV-0(B1) was demonstrated by long PCR. Analysis of several sucrose density gradients from different harvests of various manufacturers demonstrated accumulation of, and colocalization with, RT activity for the EAV-0(B1) RNA but not for a chicken cellular mRNA. Synthesis of cDNA from EAV-0(B1) RNA was shown by endogenous RT reaction. Furthermore, complexes of naturally primed EAV-0(B1) RNA with RT were demonstrated. Taken together, these data strongly suggest that EAV-0 is able to produce virus-like particles with an active RT.

And the next paper shows that retroviruses can change normal cells into cancerous cells. The title of the paper "Steps and mechanisms of oncogene transduction by retroviruses" actually means the steps and mechanisms through which retroviruses turn normal cells into cancerous cells.

Felder MP, Eychene A, Laugier D, Marx M, Dezelee P, Calothy G. Unité de Recherche Associée 1443 du Centre National de la Recherche Scientifique, Institut Curie, Centre Universitaire, Orsay, France. Steps and mechanisms of oncogene transduction by retroviruses. Folia Biol (Praha). 1994;40(5):225-35.

Oncogene transduction, the process by which a cellular gene is captured by a retrovirus was mainly described in vivo. We have developed a biological system allowing stepwise analysis of transduction mechanisms in tissue culture. Avian neuroretina (NR) cells dissected at the 8th day of embryonic development rapidly cease to divide and differentiate in culture. Serial passaging of a retrovirus that does not carry an oncogene on such cultures leads with a high frequency to the emergence of new viruses that have transduced oncogenes from the mil/raf family of serine/threonine kinases. These viruses have been selected by their ability to induce NR cell division. This experimental system allowed the isolation of the following molecular intermediates generated during the successive steps of oncogene transduction: a chimeric transcript containing viral and cellular sequences joined together by an alternative splicing mechanism; then a complete retrovirus with a 5' end identical to that of chimeric RNA; finally, a retrovirus that has acquired additional gag sequences and consequently, an increased replicative capacity. Structural analysis of these molecules led us to propose a general model for oncogene transduction in which the key step is the synthesis of chimeric RNAs. This model also explains generation of the vast majority of acutely transforming retroviruses isolated in vivo.

And the next study is fairly clear:

Johnson ES. Environmental and Molecular Epidemiology Section, National Institute of Environmental health Sciences, National Institutes of health, Research Triangle Park, NC 27709. Poultry oncogenic retroviruses and humans. Cancer Detect Prev. 1994;18(1):9-30.

Viruses of the avian leukosis/sarcoma group (ALSV) and reticuloendotheliosis viruses (REV) are highly prevalent in chickens and turkeys and naturally cause tumors in them. Commercial chickens are positive for antibodies, and a proportion actually carry infectious virus. Virus may be present in chicken products and in eggs, thus human exposure is virtually universal. The viruses show little potential for producing infectious viral particles in mammalian cells; nevertheless, they have the capacity to infect and transform mammalian cells (including human cells) in vitro, and to induce tumors in a variety of mammals, including primates. Most, but not all, of the serological studies in humans have been negative. Given the known behavior of these viruses in mammals, this was not unexpected. Moreover, there were methodological problems with most of the studies. There is some epidemiological evidence associating putative poultry exposure with cancer in humans. However, this has not been rigorously investigated. This paper is a comprehensive review of the extent of the carcinogenic potential these viruses show for humans. It is concluded, virological evidence indicates, that these viruses could conceivably have a carcinogenic potential for humans, but if so, at a level much less than in chickens. Whether this is insignificant, or translates to a real risk, is not known at the moment. Therefore, there is a need for definitive studies to completely rule out this possibility.

What all the above means is that vaccines cultured in chicken embryos will contain quantities of retroviruses that are able to cause cancer -and they can also merge with the vaccine virus itself to create dangerous new mutant viruses. And these viruses are injected straight into your body. So given that vaccines are proven to contain "retroviruses" that can lead to cancer cells in the body, this issue is quite a serious one.

Further, to add to all of the above, to actually remove these viruses is not possible. Or, to put it another way, its not economically viable for the vaccine manufacturers, as there are no other alternative culture mediums they can currently use.

Contrary to what is popularly believed, vaccines are not established to be safe. This is very well known and understood to state and national vaccine safety bodies. That's why such bodies exist in the first place. There is a whole lot that they do not know and understand, and their aims are always to make vaccines "safer". For public consumption and reassurance, they are portrayed to be safe, whilst in private meetings they discuss some of the serious issues such as this one.