Ultrastructural Analysis of Pseudorabies Virus Infection in IB-RS-2 Cell Line and with Treatment by Persea americana Extract

In this study, we focused on the cycle of replication of the Pseudorabies virus (PrV) in the swine IB-RS-2 cell line in absence or in presence of an infusion from Persea americana leaves. The ultrastructure of the Nova Prata strain virus presents the typical characteristics of Varicelovirus as well as lytic replication with total cell destruction between 18 and 24 hours post-infection (pi). Adsorption is immediate followed by fusion penetration of the virus membranes with those of the host. The capsid once inside the cell migrates to the nucleus where it disappears. Precursor viral particles appear from 4 hours and will form the nuclear crystalloids. The capsids with the viral DNA incorporated migrate to the nuclear membranes where they receive viral envelope after de-envelopment and re-envelopment constituted by cytoplasmic membranes. Then the virions appear grouped in vesicles that merge with the plasma membrane and finally are released out of the cell and become associated with it. Infected cells in the presence of an infusion of Persea americana leaves show few viral particles and many cells without signs of infection. In the initial stages of replication, they are shown pleomorphic with a different morphology when compared with the control. At 7 h post-infection double core with a single envelope are found both between the nuclear membranes and in the cytoplasm of the cell. These findings indicate that the extract may be interfering with virus replication as well as useful in detecting possible targets of inhibition.