Maternally derived neutralizing antibodies in piglets induce superior protection against circulating porcine reproductive and respiratory syndrome virus (PRRSV) under field conditions

Immunofluorescence assay (IFA) of PRRSV in MARC145 cells for viral neutralization assay. Cytopathic effects (CPE) of infected MARC145 cells were visualized (A) and stained by IFA utilizing PRRSV monoclonal antibodies and fluorescein goat anti-mouse secondary antibodies (B). The naïve parental MARC145 cells were presented (C) and examined by IFA using the same procedure (D). All pictures were recorded under ×50 magnification.