Serum activities of complement 1q and antibodies to the virulence-associated protein A are lower in foals that develop rhodococcal pneumonia.

Objective: To determine the effects of transfusion of Rhodococcus equi hyperimmune plasma (REHIP) on serum concentrations of complement component 1q (C1q) and to examine the association of serum C1q and anti-rhodococcal antibodies of newborn foals with subsequent development of rhodococcal pneumonia.

Animals/samples: Foals (n = 205) from 2 Thoroughbred breeding farms in New York transfused with REHIP between January 1, 2022, and December 1, 2022.

Procedures: Blood was collected immediately before transfusion with REHIP and again from the contralateral vein immediately after transfusion.

Intramuscular but not nebulized administration of a mRNA vaccine against Rhodococcus equi stimulated humoral immune responses in neonatal foals.

Objective: Design and evaluate immune responses of neonatal foals to a mRNA vaccine expressing the virulence-associated protein A (VapA) of Rhodococcus equi.

Animals: Cultured primary equine respiratory tract cells; Serum, bronchoalveolar lavage fluid (BALF), and peripheral blood mononuclear cells (PBMCs) from 30 healthy Quarter Horse foals.

Methods: VapA expression was evaluated by western immunoblot in cultured equine bronchial cells transfected with 4 mRNA constructs encoding VapA.