Single Dose Toxicity Study of Polysaccharide VI Conjugate Vaccine in Sprague Dawley Rats

Abstract

Typhoid fever continues to be a major public health problem according with estimates of World Health Organization. Conjugation of polysaccharides to an immunogenic protein revert the Thymus independent pattern of polysaccharides to a T-dependent pattern and induce immune response in infants. The aim of this work was to evaluate the toxicological profile a conjugate candidate vaccine against this disease through single dose study in Sprague Dawley rats. Animals were observed daily for local and systemic toxicity symptoms. Also, body weight, water and food consumption, immune response, temperature and local inflammation in the site of injection were evaluated. Gross necropsy was made at the end of the study to each rat, selected organs were weighed, and a full range of tissues was preserved for histological studies. The vaccine not evidenced clinical symptoms, deaths, local effects or adverse systemic toxicological change. Therefore, this vaccine may be considered potentially non-toxic for human.Summary: Typhoid fever remains a major public health problem according to estimates by the World Health Organization. The conjugation of polysaccharides to an immunogenic protein reverses the thymus pattern independent of polysaccharides to a dependent T pattern and induces an immune response in children. The objective of this work was to evaluate the toxicological profile of a conjugate vaccine candidate against this disease, using a single dose trial in Sprague Dawley rats. Animals were observed daily to detect symptoms of local and systemic toxicity. In addition, body weight, food and water consumption, immune response, temperature and local inflammation at the injection site were evaluated. At the conclusion of the study, macroscopic anatomopathology was performed on all animals, selected organs were weighed and all organs processed for histological studies. The vaccine showed no clinical symptoms, deaths, local effects or adverse systemic toxicological changes. Therefore, this vaccine can be considered potentially non-toxic to humans.