Brucellosis is a major threat to public health and animal husbandry. Several in vivo vertebrate models, such as mice, guinea pigs, and nonhuman primates, have been used to study Brucella pathogenesis, bacteria-host interactions, and
vaccine efficacy. However, these models have limitations whereas the invertebrate Galleria mellonella model is a cost-effective and ethical alternative. The aim of the present study was to examine the invertebrate G. mellonella as an in vivo
infection model for Brucella.
Infection assays were employed to validate the fitness of the larval model for
Brucella infection and virulence evaluation. The protective efficacy of
immune sera was evaluated by pre-incubated with a lethal dose of bacteria before
infection. The consistency between the mouse model and the larval model was confirmed by assessing the protective efficacy of two
Brucella vaccine strains. The results show that G. mellonella could be infected by Brucella strains, in a dose- and temperature-dependent way. Moreover, this larval model can effectively evaluate the virulence of Brucella strains in a manner consistent with that of mammalian
infection models. Importantly, this model can assess the protective efficacy of
vaccine immune sera within a day. Further investigation implied that haemolymph played a crucial role in the protective efficacy of
immune sera. In conclusion, G. mellonella could serve as a quick, efficient, and reliable model for evaluating the virulence of Brucella strains and efficacy of
immune sera in an ethical manner.