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In the present investigation, the effect of colchicine on La Crosse virus production and export was tested. Colchicine-treated, La Crosse virus-infected cells: (1) had decreased mean virus titers compared with those of control cells; (2) had a ratio of released to cell-associated virus of 1–1.9 whereas control cells had a ratio of 13. A colchicine-sensitive step, possibly involving microtubules, may be involved in virus production and/or release from the cell.

Minute virus of mice (MVM), a single-stranded deoxyribonucleic acid Parvovirus, was subjected to various inactivation procedures, including chemical disinfectants, heat, and ultraviolet radiation. MVM was found to be less stable than has been reported for other Parvoviruses. This virus was readily inactivated by a variety of chemical disinfectants, including alcohols, formaldehyde, glutaraldehyde, and chloroform. MVM was more sensitive to ultraviolet radiation than was Kilham's rat virus. MVM was more sensitive to heating at temperatures of 35 to 100 C than has been reported for other Parvoviruses. More than 95% of MVM infectivity was inactivated by heating (45, 60, or 100 C) for 60 min, acid (pH 2.0) treatment, or ultraviolet radiation treatment, although a small percentage (less than 2%) of the virus preparation was found to be resistant to these treatments. In addition, more than 99% of the infectivity of MVM was lost after storage at 4C for 10 weeks, although the virus was stable on storage in liquid nitrogen.

Three commercial laboratory mouse chows were fed to C57BL/KsJ db+/db+ diabetic mutants to evaluate the influence of diet on the development of diabetes. Since these mice are hyperphagic, feeding both restricted and ad libitum quantities was used to distinguish the quantitative from qualitative aspects of the diets. Over a 9 week feeding period, measurements were made of body weight, food consumption, and response to an intraperitoneal glucose challenge (GTT). Diabetic mutants allowed to feed ad libitum exhibited increased weight gain and a more advanced diabetic condition (as revealed by GTT) after only 3 weeks on Agway brand chow when compared to mice consuming the other two diets. Diabetic mutants fed restricted amounts of the three chow brands had a similar pattern of response but GTT differences did not become evident until 6 weeks on Agway, suggesting both qualitative and quantitative effects of diet on diabetes onset. The results show different responses to standard chow diets and illustrate the influence of the host genotype on the effects of a given diet. It also emphasizes the need for accurate reporting of the type of chow diet being used.

~~ Abstract. The present investigation was undertaken to determine whether A'-tetrahydrocan- nabinol (A9-THC) decreases host resistance to herpes simplex virus type 2 vaginal infection in the guinea pig. The guinea pig was selected as the host since it has been shown to express a spectrum of primary herpes genitalis which is similar to that in humans. Animals were administered A9-THC or vehicle intraperitoneally on Days 1-4, 8- 1 1, and 15- 18. Herpes simplex virus was introduced intravaginally on Day 2. Host resistance to virus infection was assessed by comparing frequency and severity of lesions, virus shedding, and animal mortalities. Virus-infected animals treated with drug at doses of 4 and 10 mg/kg exhibited significantly greater severity of genital disease during the 30-day period of study when compared to virus-inoculated vehicle controls. A direct relationship was noted between dose of A9-THC and cumulative mortalities on Day 14 following primary infection. These results indicate that A9-THC decreases host resistance to herpes Simplex Virus type 2 vaginal infection in the guinea pig. 0 1986 Society for Experimental Biology and Medicine.

Summary St. Louis encephalitis virus was isolated on 23 occasions from mosquitoes collected between September 7 and October 25 at widely separated localities of the four-county Tampa Bay area during the St. Louis encephalitis epidemic of 1962. Twenty-two of these isolations were obtained from 485 pools of Culex nigripalpus; the 23rd was from 91 pools of Melanoconion, a subgenus of Culex. The mosquitoes were collected alive in battery-powered light traps and traps baited with ducklings or chicks. These isolations indicate that infected vectors were prevalent over a vast area exposing the human population to infection throughout the region.

Summary Differentiation of members of the California group of arboviruses was accomplished using the double diffusion in gel technique of Ouchterlony. Eight antigenic subgroups were defined on the basis of unique antigenicities. These groupings confirmed the individuality of isolates described in the literature and allowed classification of new isolates. Unique, yet identical, patterns of antibody specificity were found in convalescent sera of 11 individuals with central nervous system disease.

Tensaw virus, a new member of the Bunyamwera arbovirus group (named for the river bordering the area in south Alabama where the prototype strain was found), is sensitive to sodium deoxycholate, relatively heat-stable at 37°C, and filterable through membranes with an APD of 220 millimicrons, but not through 100 millimicrons. The virus produced clinical disease and death in suckling and adult mice but did not produce disease in rabbits, guinea pigs, or hamsters. The virus grows well in hamster-kidney, HeLa, duck-embryo fibroblast, and monkey-kidney tissue-culture systems, producing cytopathic effects and plaques. Detailed antigenic comparison of eight strains of Tensaw virus with five known Bunyamwera-group viruses was made and the relation of the Tensaw strains to other Bunyamwera viruses was discussed.

Summary A total of 25,240 mosquitoes was captured in the Tampa Bay area during September and October 1962, using miniature, battery-operated light traps. These were tested in suckling mice in 1,114 pools. A total of 19 isolations of St. Louis encephalitis virus was made, 18 from Culex nigripalpus and a single one from Anopheles crucians. Twenty-nine other virus isolations were made. Twenty-eight were from An. crucians and have been identified as a new virus related to Cache Valley virus of the Bunyamwera arbovirus group; the other was an unidentified virus of the California arbovirus group from Aedes atlanticustormentor.

Venezuelan equine encephalitis virus was isolated three times from the Culex (Melanoconion) species of mosquitoes collected in south Florida in June, July, and October, 1963. Specific antibody was present in 16 of 28 Peromyscus gossypinus (cotton mice) and 3 of 16 Sigmodon hispidus (cotton rats) sampled from one of the infected sites in January 1964.

A 49-year-old splenectomized man had an infection from an unidentified, gram-positive, rod-shaped bacterium that adhered to the majority of his peripheral-blood erythrocytes. On transmission electron microscopy, the bacterium was seen to be extra-erythrocytic and was 0.2 micrometer wide by 1.0 to 1.7 micrometer long. It possessed a thick, granular cell wall, a trilamellar membrane external to the cell wall and prominent mesosomes. Attempts to cultivate the organism in vitro or to duplicate the patient's disease in splenectomized animals were unsuccessful. The patient's response suggested that the bacterium was susceptible to cell-wall-active antibiotics and to chloramphenicol but not to tetracycline. This bacterium may be the cause of other chronic, fever-producing, multisystem diseases of unknown origin.

The teratogenic effects in mice of Colorado tick fever (CTF) virus, a human pathogen, were demonstrated. Various routes of inoculation, gestational periods, and dosages of virus were studied. The incidence of stillbirth and neonatal death increased significantly after inoculation of pregnant mice with CTF virus. CTF virus crossed the placenta and replicated to high titers in the placental and fetal tissues. Mice that survived the first six weeks of life had neutralizing antibody to CTF virus. Neutralization tests, in which pregnant mice were inoculated with both CTF virus and specific antiserum to CTF virus, validated the teratogenic effects of CTF virus in mice.

SummaryMinute virus of mice was found to be closely associated with the erythrocyte fraction of the blood of infected mice, with peak viremia occurring on day 5 or 6 after intraperitoneal inoculation. The association with erythrocytes suggests a common mechanism of transplacental transport for the teratogenic Parvoviruses. In addition, MVM was found to be a relatively poor inducer of interferon and to be very sensitive to the inhibiting action of interferon.