EFFECT OF IN VITRO CULTIVATION ON THE PATHOGENICITY OF WEST NILE VIRUS

Area of Science:

• Virology
• Pathogen Cultivation
• Infectious Disease Research

Background:

• West Nile virus (WNV) is a significant public health concern.
• Understanding viral adaptation and changes in pathogenicity during in vitro cultivation is crucial for vaccine development and disease control.

Purpose of the Study:

• To investigate the effects of prolonged in vitro cultivation on West Nile virus pathogenicity.
• To determine if extended propagation in cell culture alters the virus's ability to cause fatal infections in animal models.

Main Methods:

• Cultivation of West Nile virus in suspended cell culture media with various tissue components.
• Serial propagation of the virus over multiple passages.
• Assessment of viral pathogenicity in mice and hamsters via peripheral and cerebral inoculation routes.
• Evaluation of the influence of animal age and passage level on viral virulence.

Main Results:

• West Nile virus survived in culture for at least 32 days.
• Prolonged cultivation led to a marked reduction or complete loss of pathogenicity in mice and hamsters following peripheral inoculation.
• The virus retained its lethal effect via the cerebral route in mice, irrespective of passage level.
• Younger mice (3 days old) required more passages (up to 68) to show diminished virulence compared to older mice (14+ days old).
• Prolonged cultivation rendered the virus avirulent for hamsters via the intraperitoneal route.

Conclusions:

• In vitro cultivation of West Nile virus can significantly alter its pathogenicity, particularly affecting peripheral infectivity.
• Viral adaptation in cell culture may lead to a loss of virulence, offering insights into host-pathogen interactions.
• Age-dependent susceptibility in animal models influences the observed reduction in viral pathogenicity during in vitro evolution.