RESUMEN
Because of the exquisite sensitivity of the murine histamine sensitization test (HIST) in detecting minute amounts of active pertussis toxin (PTx), this animal-based test has been used to assure the safety of acellular pertussis vaccines in the United States and other countries around the world. Prompted by humane considerations, efforts are underway to find a suitable in vitro replacement assay that has critical attributes comparable to that of the HIST. In this study, we compared the sensitivity of the in vivo HIST with an in vitro Chinese Hamster Ovary (CHO) cell-based assay. Using vaccine samples that had been spiked with PTx, we found that both assays were capable of detecting as little as 4-10â¯ng of active pertussis toxin per dose of vaccine; thus, the sensitivities of the two assays are comparable. Because the strength of adsorption of PTx to the vaccine adjuvant could change over time, we also used both assays to examine the bioavailability of PTx in spiked vaccine samples that had been stored at 25⯰C for 9â¯weeks, mimicking long term vaccine storage conditions. We found that both assays detected similar amounts of active PTx in these samples, indicating that bioavailability of the toxin in stored samples was similar. Taken together, our results indicate that critical attributes of the HIST are met by the CHO cell assay used in this study and provide proof of concept that the CHO cell assay may be further considered as a replacement for the in vivo HIST.
Asunto(s)
Alternativas a las Pruebas en Animales/métodos , Bioensayo/métodos , Toxina del Pertussis/análisis , Vacuna contra la Tos Ferina/efectos adversos , Vacunas Acelulares/efectos adversos , Animales , Células CHO , Cricetinae , Cricetulus , Histamina/inmunología , Técnicas In Vitro/métodos , Ratones , Toxina del Pertussis/efectos adversos , Vacuna contra la Tos Ferina/administración & dosificación , Vacunas Acelulares/administración & dosificación , Tos Ferina/prevención & controlRESUMEN
We report that a toxin neutralization assay (TNA) can detect a decrease in the immunogenicity of anthrax vaccines as a consequence of brief exposure to elevated temperature. This attribute of TNA may help in adopting immunogenicity as a replacement of the current potency test, which involves protection from lethal challenge.
