Una vacuna para la lepra: evaluación de su necesidad y estrategia de desarrollo

Las vacunas vivas atenuadas como la BCG aunque han demostrado capacidad de estimular una respuesta inmunológica protectora en humanos en algunos ensayos clínicos, no resultan actualmente las más apropiadas con la gran cantidad de infectados HIV ya que podrían por sí mismas ser causa de enfermedad. Este trabajo revisa las necesidades actuales y posibilidades de aplicación de una vacuna frente a la lepra diseñada con los planteamientos y conocimientos proporcionados por las nuevas tecnologías, sobre todo en los campos de la Inmunología y Biología Molecular (AU)

Rinderpest virus infection in primary bovine skin fibroblasts.

Rinderpest virus (RPV) replicated to a high titre in primary bovine skin fibroblasts. The course of infection was similar to that seen in established cell lines. Virulent field virus grew at a faster rate than the fully attenuated vaccine strain of the virus. Virus antigen expression, as measured by FACScan analysis, correlated with the time course of infection for the two strains in cell cultures. Wild type virus, obtained directly from cattle, infected cells at a slower rate than virus passaged even once in primary bovine skin fibroblasts. This is the first report of a productive infection of primary bovine skin fibroblasts by wild type RPV.

Viral protein 1 sequence analysis of three infectious bursal disease virus strains: a very virulent virus, its attenuated form, and an attenuated vaccine.

Comparisons between sequences of very virulent, virulent, and attenuated strains of the infectious bursal disease virus (IBDV) may indicate sites on the genome co-inciding with virulence. In an attempt to detect if such sites exist on the coding region of segment B, viral protein 1 (VP1) (encoded for by segment B) of a very virulent Israeli virus, IL3; its attenuated strain, IL4; and the attenuated Winterfield vaccine 2512 were cloned and sequenced. A comparison was made among them and with six other published sequences of segment B. Six nucleic acids distinguished between IL3 and IL4, three of which were predicted to be expressed as amino acids. A striking similarity between the VP1 sequences of 2512 and P2 (an attenuated German strain) was discovered. Although conclusions could not be drawn concerning attenuation sites on VP1, the analysis performed on the VP1 sequences of the two Israeli strains and the Winterfield 2512 strain sheds light on the phylogeny of IBDV and contributes to the accumulating information that may lead to the identification of virulence-related sites of this virus.

Analysis of a coded panel of licensed vaccines by polymerase chain reaction-based reverse transcriptase assays: a collaborative study [seecomments].

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.