Infections of Congenitally Athymic (Nude) and Normal Mice with Avirulent and Virulent Strains of Venezuelan Encephalitis Virus

Abstract

Two strains of Venezuelan encephalitis virus that are avirulent for normal BALB/c mice inoculated subcutaneously were also avirulent for infected congenitally athymic (nude) mice of the same strain. Viremias were of similar magnitudes and durations in normal and nude mice. Brain concentrations were higher in nude mice with the one avirulent strain tested, although the periods of detectable virus

Susceptibility of BALB/c-nu/nu Mice and BALB/c Mice to Equine Herpesvirus 9 Infection

“…In addition, a low expression level of the mRNA ORF30 gene was observed throughout the experiment. These results were quite similar to those obtained by LeBlanc et al, 28 who studied the infection of normal mice with a virulent Venezuelan encephalitis virus.…”

Recombinant vaccinia virus/Venezuelan equine encephalitis (VEE) virus protects mice from peripheral VEE virus challenge

“…Mice immunized with the recombinant virus developed lower anti-VEE antibody levels than did TC-83-immunized mice. This differential response to either vaccine was expected since TC-83 virus replicates in most tissues of mice (30,31). TC-83 virus can be recovered in nasopharyngeal secretions of immunized humans (37) and monkeys (38).…”

Attenuation of Venezuelan equine encephalitis virus strain TC-83 is encoded by the 5'-noncoding region and the E2 envelope glycoprotein

“…VEE virus virulence correlates well with high and prolonged viremia in equines (27,54) and laboratory rodents (20,24,33). In mice, infection with virulent VEE virus causes marked lymphocytic depletion and necrosis in the spleen, lymph nodes, and bone marrow.…”

“…Mice infected with virulent virus develop encephalitis that involves the entire brain, spinal cord, and meninges, with severe perivascular cuffing, gliosis, and necrosis of neurons, especially the large motor neurons in the spinal cord (15)(16)(17). However, mice challenged peripherally with the attenuated TC-83 virus develop lower virus titers in the blood and brain and are spared the histopathological lesions that occur in the spleen, lymph nodes, and brain tissue of mice infected with virulent VEE virus (33).…”