Submitted to: Emerging Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2001
Publication Date: N/A
Citation: Interpretive Summary: Human vaccines have been used effectively to reduce and prevent morbidity and mortality from many viral infections. Occasionally, production of such vaccines has been complicated by inadvertent contamination with adventitious agents originating from substrates used for propagation of vaccines. Recently, vaccines against measles, mumps and yellow fever that have been produced in chicken-embryo cells tested positive for a protein compound termed reverse transcriptase (RT), suggesting the presence of a group of avian viruses known as retroviruses. The RT positive reaction was shown to be due to presence of endogenous (naturally present in chicken cells) retrovirus elements. In the current study, serum and blood cells from recipients of an RT positive measles, mumps and rubella vaccine (MMR) tested negative for the presence of infection with these chicken retrovirus elements. This work provided significant information to public health officials regarding the safety of this important human vaccine. Also, the information should be helpful to human vaccine manufacturers in their attempts to assure safety and quality of their vaccines.
Technical Abstract: The identification of endogenous avian leukosis virus (ALV) and endogenous avian retrovirus (EAV) in currently used chick-cell derived measles and mumps vaccine have raised concerns about transmission of these retroviruses to vaccine recipients. We tested recipients of measles, mumps and rubella MMR) vaccines for evidence of infection with ALV and EAV by serologic and molecular methods. A western blot (WB) assay for detection of antibodies to endogenous ALV was developed and validated. Analysis of serum samples from 206 MMR vaccine recipients was consistently negative by WB method. Peripheral blood lymphocytes (PBL) samples from 104 of these vacinees were further tested by PCR for both ALV and EAV proviral sequences, and were all found to be negative. Matching serum samples were tested by RT-PCR for ALV and EAV RNA and all 104 samples were negative, suggesting absence of viremia. These findings do not support the presence of either ALV or EAV infection in MMR recipients and provide reassurance for current immunization policies.