The Attenuated Pseudorabies Virus Vaccine Strain Bartha K61: A Brief Review on the Knowledge Gathered during 60 Years of Research

Pseudorabies virus (PRV) is a member of the alphaherpesvirus subfamily of the herpesviruses and is the causative agent of Aujeszky’s disease in pigs, causing respiratory, neurological, and reproductive symptoms. Given the heavy economic losses associated with Aujeszky’s disease epidemics, great efforts were made to develop efficacious vaccines. One of the best modified live vaccines to this day is the attenuated Bartha K61 strain. The use of this vaccine in extensive vaccination programs worldwide has assisted considerably in the eradication of PRV from the domesticated pig population in numerous countries. The Bartha K61 strain was described in 1961 by Adorján Bartha in Budapest and was obtained by serial passaging in different cell cultures. Ever since, it has been intensively studied by several research groups, for example, to explore its efficacy as a vaccine strain, to molecularly and mechanistically explain its attenuation, and to use it as a retrograde neuronal tracer and as a vector vaccine. Given that the Bartha K61 vaccine strain celebrates its 60th birthday in 2021 with no sign of retirement, this review provides a short summary of the knowledge on its origin, characteristics, and use as a molecular tool and as a vaccine.

Download Full-text

The Valproic Acid Derivative Valpromide Inhibits Pseudorabies Virus Infection in Swine Epithelial and Mouse Neuroblastoma Cell Lines

Viruses ◽

10.3390/v13122522 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2522

Author(s):

Sabina Andreu ◽

Inés Ripa ◽

Beatriz Praena ◽

José Antonio López-Guerrero ◽

Raquel Bello-Morales

Keyword(s):

Valproic Acid ◽

Cell Line ◽

Pseudorabies Virus ◽

Neuroblastoma Cell ◽

Antiviral Effect ◽

Nucleoside Analogues ◽

Economic Losses ◽

Suitable Alternative ◽

Aujeszky's Disease ◽

Aujeszky’S Disease

Pseudorabies virus (PRV) infection of swine can produce Aujeszky’s disease, which causes neurological, respiratory, and reproductive symptoms, leading to significant economic losses in the swine industry. Although humans are not the natural hosts of PRV, cases of human encephalitis and endophthalmitis caused by PRV infection have been reported between animals and workers. Currently, a lack of specific treatments and the emergence of new PRV strains against which existing vaccines do not protect makes the search for effective antiviral drugs essential. As an alternative to traditional nucleoside analogues such as acyclovir (ACV), we studied the antiviral effect of valpromide (VPD), a compound derived from valproic acid, against PRV infection in the PK15 swine cell line and the neuroblastoma cell line Neuro-2a. First, the cytotoxicity of ACV and VPD in cells was compared, demonstrating that neither compound was cytotoxic at a specific concentration range after 24 h exposure. Furthermore, the lack of direct virucidal effect of VPD outside of an infected cell environment was demonstrated. Finally, VPD was shown to have an antiviral effect on the viral production of two strains of pseudorabies virus (wild type NIA-3 and recombinant PRV-XGF) at the concentrations ranging from 0.5 to 1.5 mM, suggesting that VPD could be a suitable alternative to nucleoside analogues as an antiherpetic drug against Aujeszky’s disease.

Download Full-text