Differential expression of vitellogenin in honey bees (Apis mellifera) with different degrees of Nosema ceranae infection
Karina Antúnez, Yamandú Mendoza, Estela Santos and Ciro Invernizzi
Nosema apis and Nosema ceranae are causative agents of Nosemosis in the honey bee Apis mellifera, although N. ceranae may cause a more virulent disease. Selection of colonies with high tolerance to N. ceranae could be important for reducing problems caused by this pathogen. The aim of the present work was to evaluate the existence of honey bee colonies with different degrees of N. ceranae infection and test if this difference could be related to the immune response or vitellogenin expression. Healthy honey bee colonies were relocated to a plantation of Eucalyptus grandis to favour natural infection of N. ceranae. Fifteen and thirty days after relocation, the proportion of infected bees and the number of N. ceranae spores per field were quantified. The colonies with higher and lower levels of infection (HL and LL, respectively) were selected. Newly emerged bees from both colonies were artificially infected with N. ceranae and seven days after infection the expression of immune related genes and vitellogenin was evaluated by real time PCR. No significant differences were observed in expression of abaecin, hymenoptaecin, defensin, glucose dehydrogenase or lysozyme mRNA levels between infected bees from HL and LL colonies or between control bees from both colonies. Vitellogenin expression was higher in bees from the LL colony than in bees from the HL colony, when infected or control bees were compared between them. This protein possesses pleiotropic effects and is a central element in the life-history of honey bees. For that reason, its differential expression could be associated with resistance to N. ceranae.
Apis mellifera, Nosema ceranae, vitellogenin, immune response, real time PCR