The possible role of circulating interferon on autointerference in mice infected intraperitoneally with West Nile virus

X-linked resistance of mice to high doses of herpes simplex virus type 2 correlates with early interferon production

Mice inoculated intraperitoneally with herpes simplex virus type 2 develop focal necrotizing hepatitis and eventually die from ascending myelitis and encephalitis. The genetics of resistance to the infection were analyzed in crosses between resistant C57BL/10 mice and susceptible BALB/c mice. It was shown that the resistance of C57BL/10 mice to hepatitis induction was influenced by an X-linked dominant gene as previously shown for the GR mouse strain. The course of infection in the liver pointed to early, natural defense mechanisms as being responsible for the difference between the mouse strains, whereas the clearance of virus from the liver, probably mediated by specific immunity, was exerted at the same time and with equal efficiency for all groups of mice. In mortality experiments, resistance was shown to be an autointerference phenomenon in that a considerable number of C57BL/10 mice survived an intraperitoneal injection of 10(6) PFU, whereas all mice were killed by 10(5) PFU. This resistance of C57BL/10 mice to high doses of HSV-2 was retrieved in all groups of F1 mice in crosses between C57BL/10 and BALB/c mice except the (BALB/c female X C57 male) male group, in which the mice receive the X chromosome from the susceptible BALB/c female. Thus, the autointerference phenomenon also seems to be influenced by loci on the X chromosome. A similar pattern of inheritance was observed when early interferon induction (4 to 5 h after infection) in response to HSV-2 was measured. The possible relevance of this early interferon response in conjunction with other potential natural defense mechanisms is discussed.

Virus infections in infant mice causing persistent impairment of turnover of brain catecholamines

Newborn mice were inoculated with attenuated Coxsackie type B4 virus. Three-to-4-day old mice were infected with yellow fever virus vaccine. A number of mice survived the acute infections. Some of these demonstrated residual neurological symptoms, some showed recovery from symptoms while others survived the infection without revealing symptoms of disease. Determinations of dopamine, noradrenaline, 5-hydroxytryptamine, homovanillic acid and 5-hydroxyindoleacetic acid in the inoculated brains indicated an imparied turnover of neurotransmitters. Subnormal concentrations of catecholamines and homovanillic acid were encountered in the acutely-infected mice as well as among the survivors. Failure to synthesize catecholamines was observed not only in mice demonstrating symptoms of disease or in animals which recovered from their infection but also among a proportion of the mice which never demonstrated neurological symptoms. In contrast, 6-week-old Swiss albino mice infected with West Nile virus showed no effect on the turnover of brain monoamines either in acutely infected mice or in animals which survived the acute infection. Herpes simplex virus infection of 3-week-old mice induced during the acute infection an increased release of neurotransmitters. When these mice were "cured" of the infection by increasing the environmental temperature the elevated turnover of monoamine metabolism was normalized. Two months later there were no differences in concentrations of catecholamines or homovanillic acid between infected animals or uninfected controls. Thus, persistent impairment of brain monoamine metabolism was induced in mice infected when very young. The possible importance of the observations, in particular the findings of an impaired turnover after subclinical infection, is discussed.