Anticorpos IgY específicos para rotavírus do grupo Auma abordagem terapêutica para rotavirose em Macaca fascicularis

The production of antibodies in chickens and the extraction of specific antibody suspensions from egg yolk (IgY) are increasingly attracting the interest of the scientific community, as demonstrated by the significant growth of the IgY literature. This approach, which is suitable to a large - scal e production, offers several advantages such as the low cost and high efficiency of the technique, in view of the extraordinary yield of IgY by a one hen (20 g – 40 g IgY per year), and its suitability to a more bioethical manner for hen keeping. Of note, the IgY - technology offers new possibilities for application in human and veterinary diagnostics and therapeutics, including strategies for the treatment of severe intestinal diseases in children, particularly in poor countries. In this study, we aimed to e valuate the therapeutic efficacy of the IgY by using young cynomolgus monkeys ( Macaca fascicularis ) challenged with human rotavirus group A (RVA), a major cause of morbidity and mortality in children worldwide, especially in developing countries. For this purpose, specific IgY antibodies against RVA were produced in hens, purified by polyethylene glycol, characterized by polyacrylamide gel electrophoresis, western blotting and a neutralization assay in a cell culture system (MA - 104). This preliminary experi ment has yielded a high concentrated suspension of anti - rotavirus specific IgY (anti - RVA IgY) (average 37 mg/ml). The cynomolgus experimental infection model was established after a single administration of a human rotavirus suspension (3.1x10 6 FFU/ml) by oral gavage. The confined animals were followed during a period of eleven days, observed for clinical signs, measurement of serum and faecal viral load, and evaluation of hematology and serum electrolytes. The main clinical sign (observed in two of the sev en inoculated monkeys) was diarrhea associated with a decrease in serum potassium during three days, followed by recovery. Viral RNA was detected in both serum and faeces of the infected animals, thus suggesting viral replication. In cynomolgus experimenta l immunotherapy, the monkeys were inoculated with human RVA (3.1x10 7 FFU/ml), challenged with the anti - RVA IgY suspension previously obtained, and monitored during five days by using the same clinical and biochemical parameters, as previously established. The therapeutic efficacy of the immunotherapy with IgY was confirmed by the absence of episodes of diarrhea, which is recognized as the "gold standard" for clinical efficacy, although viral RNA had been detected in faeces of all but one of the inoculated m onkeys. The duration of RNA detection was shortened in two of the three groups of animals treated with IgY, when compared to the positive control. One animal, which was orally and intravenously treated with the anti - RVA IgY, had no RNA detected in faeces. In conclusion, the application of specific anti - RVA IgY antibodies, produced in hens, presents efficacy in the treatment of acute gastroenteritis caused by human rotavirus group A. Our results also confirm that cynomolgus monkeys can be considered suscepti ble hosts to infection with human RVA, and pointed to the necessity of sanitary control of human rotavirus disease in the breeding colonies of cynomolgus monkeys. Our preliminary results suggest the promising role of passive immunotherapy using anti - RVA Ig Y in experimental infection with human rotavirus group A. However, a direct approach to the pathogenesis of enteric tract infection will provide additional data to confirm the effectiveness of the IgY treatment.