Specific egg yolk antibodies (IgY) confer protection against Acinetobacter baumannii in a murine pneumonia model.

Abstract

Acinetobacter baumannii, an increasingly serious health threat, is considered as one of the six most dangerous microbes of high mortality rate. However, treatment of its infections is difficult because of the lack of efficient antibiotic or commercial vaccines. Passive immunization through administration of specific antibodies such as IgY, could be an attractive practical solution. In the current study, antigenicity of two recombinant outer membrane proteins (OmpA and Omp34) as well as inactivated whole cell of A. baumannii was assessed by ELISA. Moreover, prophylactic effects of specific IgY antibodies (avian antibody) raised against these antigens were evaluated in a murine pneumonia model. The specific IgY antibodies had various prophylactic effects in the pneumonia model. OmpA was the most potent antigen in terms of triggering antibody and conferring protection. While a synergic effect was observed in ELISA for antibodies raised against a combination of OmpA and Omp34 (which are known as Omp33-36 and Omp34kDa), an antagonistic effect was unexpectedly seen in challenges. The reason for this phenomenon remains to be precisely addressed. All the specific IgY antibodies could protect mice against pneumonia caused by A. baumannii. The specific IgY antibodies could be employed as a pharmaceutical against pneumonia caused by A. baumannii.