ABSTRACT
The use of yellow fever (YF) virus 17D strain for vaccine production adapted in Brazil since its introduction in 1937 was reviewed. This was possible due to the availability of official records of vaccine production. The retrieved data highlight the simultaneous use of several serially passaged 17D substrain viruses for both inocula and vaccine preparation that allowed uninterrupted production. Substitution of these substrain viruses became possible with the experience gained during quality control and human vaccination. Post-vaccinal complications in humans and the failure of some viruses in quality control tests (neurovirulence for monkeys) indicated that variables needed to be reduced during vaccine production, leading to the development of the seed lot system. The 17DD substrain, still used today, was the most frequently used substrain and the most reliable in terms of safety and efficacy. For this reason, it is possible to derive an infectious cDNA clone of this substrain combined with production in cell culture that could be used to direct the expression of heterologous antigens and lead to the development of new live vaccines
Subject(s)
Humans , Animals , History, 20th Century , Chick Embryo , Yellow Fever Vaccine/history , BrazilABSTRACT
Inexistem na literatura estudos sobre o possível papel das chupetas na transmissäo da diarréia. Realiza um estudo transversal em 354 crianças menores de dois anos em duas vilas da periferia urbana de Pelotas, RS, Brasil, com precárias condiçöes socioeconômicas. A maioria das crianças (79 por cento) usava chupeta, 15 por cento nunca as haviam utilizado e 6 por cento já haviam abandonado o hábito. Dentre os usuários, 38 por cento passavam a maior parte do tempo fazendo uso da chupeta (uso intenso). Foram realizadas culturas para coliformes fecais em 93 por cento das chupetas em uso, indicando que 49 por cento estavam contaminadas. Nas duas semanas anteriores à entrevista, 35 por cento das crianças apresentaram diarréia - 40 por cento as de uso intenso, 32 por cento entre usuárias em tempo parcial e 37 por cento entre näo usuários. Apesar da forte presença de coliformes fecais, parece näo existir associaçäo entre uso de chupeta e diarréia
Subject(s)
Infant, Newborn , Infant , Humans , Diarrhea, Infantile , Enterobacteriaceae/isolation & purification , Infant Care , Socioeconomic Factors , Brazil , Diarrhea, Infantile/epidemiology , Equipment ContaminationABSTRACT
Virus titration is an important step required on viral vaccines quality control. "Plaque assay", which emplosys several types of everlay media, is usually used on viral titrations. In this paper we describe the use of apioca as an overlay media. Firstly, the toxicity of Tapioca was tested on Vero cells inoculated or not with the Yellow Fever virus (YF) 17 DD vaccine strain. Secondly, different batches of the 17 DD virus using the Tapioca. Tapioca was also shown to be a suitable overlay to be used in thermostability and plaque reduction neutrabilization tests. Other systems could benefit from the use of Tapioca as an overlay, since it was possible to titer. Measles virus in Vero cells. Tapioca is a cheap Brazilian product, is locally available, easy to use, and reliable. Its use is suggested