Brefeldin A arrests the maturation and egress of herpes simplex virus particles during infection

Herpes Simplex Virus (HSV) requires the host cell secretory apparatus for the maturation and egress of newly synthesized viral particles. Not only do viral glycoproteins rely on the host ER and Golgi compartments for their proper processing, it is believed that enveloped particles are transported through these same organelles for their export out of the cells. Brefeldin A (BFA) is a compound that induces retrograde movement of material from the Golgi apparatus to the ER and causes the disassembly of the Golgi complex. In this study, the effects of BFA on the propagation of HSV-1 in infected cells were examined. Release of viral particles from infected cells was inhibited by as little as 1 µg/ml BFA. Further analysis revealed that BFA did not affect the normal assembly of viral nucleocapsids, but did block the movement of newly-enveloped particles from the nucleus into the cytoplasm. Naked nucleocapsids were found in the cytoplasm of infected cells treated with BFA, however, these particles were neither infectious, nor were they released from the cells. Although BFA altered the distribution of viral glycoproteins in infected cells, this alteration was reversed within 2 hours after the removal of BFA. In contrast, the BFA-induced blockage to viral release was not fully reversed after BFA was removed and cells were allowed to recover in fresh medium for 3 hours. These findings indicate that the BFA-induced retrograde movement of material from the Golgi complex to the ER early in infection arrests the ability of the host cell to support the maturation and egress of enveloped viral particles. Furthermore, exposure of infected cells to BFA during the exponential release phase of the viral life cycle can cause irreversible damage to the egressing particles. This suggests that productive growth of HSV-1 in infected cells relies on a series of events that, once disrupted by agents such as BFA, cannot be easily reconstituted.Science, Faculty ofMicrobiology and Immunology, Department ofGraduat