Quantitative Studies on Fabrics as Disseminators of Viruses: IV. Virus Transmission by Dry Contact of Fabrics

Cotton and woolen fabrics and fabrics of synthetic fibers were exposed by direct contact (pipette) and by aerosolization to poliovirus and to vaccinia virus in separate experiments, allowed to dry for 16 hr at 25 C in 35% relative humidity, and randomly tumbled with sterile swatches of the same fabrics for 30 min. By use of a HEp-2 cell assay system, up to 10^3.5 CCID₅₀ of poliovirus per ml and 10^4.4 CCID₅₀ of vaccinia virus per ml were recovered from the originally sterile fabrics as early as 1 to 10 min after contact. Maximum transfer of both viruses was achieved with wool blanket material, although high titers of vaccinia virus were recovered from all fabrics tested. Poliovirus placed on the fabrics in an aerosol tended to be transferred to the sterile fabrics at a greater rate than when it was placed on the fabrics by direct contact. The method of exposure had essentially no effect on the rate of transfer of vaccinia virus.     

Quantitative Studies on Fabrics as Disseminators of Viruses: II. Persistence of Poliomyelitis Virus on Cotton and Wool Fabrics

The length of time that poliovirus could be recovered from wool gabardine and blanket, and from cotton sheeting, terry cloth, and knit jersey fabrics was determined under conditions of controlled temperature and humidity (25 C in 35 and 78% relative humidities). Three types of exposure of the fabrics to viruses were used: direct contact, aerosol, and virus-containing household dust having a high content of textile fibers. When held in 35% relative humidity, virus persisted for 20 weeks on wool fabrics, but only 1 to 4 weeks on cotton fabrics. At this relative humidity, virus titers on wool fabrics decreased rapidly to low but detectable levels which persisted for long periods of time, whereas in 78% relative humidity the decrease in virus titer was less rapid, but the period of viral persistence was shorter. Generally, virus titers on cotton fabrics held in both relative humidities decreased exponentially to an undetectable level. The method of exposure to virus had a definite effect on the duration of viral persistence on a given fabric. Virus contained in household dust was least stable.     

Quantitative Studies on Fabrics as Disseminators of Viruses: I. Persistence of Vaccinia Virus on Cotton and Wool Fabrics

The persistence of vaccinia virus on wool (blanket and gabardine) and cotton (sheeting, terry cloth, and knit jersey) fabrics was studied. The fabrics were exposed to the virus by three methods: direct contact, aerosol, and virus-containing dust having a high content of textile fibers. Fabrics exposed to virus by each method were held in 35 and 78% relative humidities at 25 C. Virus was recovered for up to 14 weeks from wool fabrics exposed to virus and held in the low humidity. In contrast, virus persisted for shorter periods of time on the cotton fabrics. No virus was detected on terry cloth as early as 3 days after exposure to virus. The virus appeared to be less stable in the high humidity, and the method of exposure of the fabrics to virus apparently had an effect upon the persistence of the agent. On all fabrics, viral persistence was of sufficient duration to be of epidemiological significance.     

Quantitative Studies on Fabrics as Disseminators of Viruses: III. Persistence of Vaccinia Virus on Fabrics Impregnated with a Virucidal Agent

Eight compounds were tested in vitro for virucidal and antiviral activity against poliovirus and vaccinia virus. These compounds included five quaternary ammonium salts, two bromosalicylanilides, and neomycin sulfate, an antibiotic. None of the compounds was active against poliovirus, but virucidal activity was demonstrated against vaccinia virus with three of the quarternary ammonium compounds: n-alkyl (C14, C12, C16) dimethyl benzyl ammonium chloride, di-isobutyl cresoxy ethoxy ethyl dimethyl benzyl ammonium chloride monohydrate, and n-alkyl (60% C14, 30% C16, 5% C12, 5% C18) dimethyl benzyl ammonium chlorides plus n-alkyl (50% C12, 30% C14, 17% C16, 3% C18) dimethyl ethylbenzyl ammonium chlorides. Wool blanketing, wool gabardine, and cotton sheeting materials were impregnated with the first of the above virucidal compounds, and the persistence of vaccinia virus on these fabrics was compared with the persistence of the agent on nonimpregnated fabrics of the same type held at 25 C in 35 and 78% relative humidity. No virus could be recovered from the chemically treated fabrics at any time after virus exposure, whereas the virus persisted as long as 4 weeks on nonimpregnated materials. Viable vaccinia virus was also found to persist less than 1 day on a cotton fabric finished with a wash-and-wear modified triazone resin. Poliovirus persisted less than 5 days on this wash-and-wear fabric.     

Potentially Infectious Agents Associated with Shearling Bedpads: I. Effect of Laundering with Detergent-Disinfectant Combinations on Polio and Vaccinia Viruses

Glutaraldehyde-tanned woolskin pads which are used for the prevention of decubitus ulcers in bed patients were experimentally contaminated with polio or vaccinia viruses. Two methods of exposure, direct contact and aerosol, were used in separate experiments. Attempts were made to remove or inactivate these virus contaminants by laundering the woolskins in a quaternary ammonium disinfectant, a phenolic disinfectant, or alkalinized glutaraldehyde, in combination with an anionic detergent or a nonionic detergent. The effect of a commercial detergent-sanitizer was also studied. The virus titers were significantly reduced in all experiments, but only laundering in glutaraldehyde in combination with either detergent lowered the vaccinia virus titers to below detectable limits. High concentrations of glutaraldehyde altered the texture of the wool and leather apparently by precipitating a component of the detergent onto the fibers. In all the poliovirus experiments, the virus was still detectable on either or both the wool and the leather of the pads after laundering. The rinse water from each experiment was tested for the presence of virus. No vaccinia virus was recovered, but poliovirus was demonstrated in titers up to 10(3) cell culture 50% infectious doses.     

Viruses of Entamoeba histolytica V. Ultrastructure of the Polyhedral Virus V301

The polyhedral amoebal virus V(301) presents sectioned profiles consistent with its having icosahedral (532) symmetry. The DNA appears to be packed in an orderly, folded arrangement of lesser symmetry.     

Saprozoic Nematodes as Carriers and Disseminators of Plant Pathogenic Bacteria

The plant pathogenic bacteria Agrobacterium tumefaciens (Smith and Townsend) Conn. (strain 5-14 Deep), Erwinia amylovora (Burill) Winslow et al., E. carotovora (Jones) Holland and Pseudornonas phaseolicola (Burk.) Dows. (ICPB-PM3) and the red-pigmented non-pathogen Serratia marcescens Bizio were hosts for the saprozoic nematode Pristionchus Iheritieri (Maupas, 1919) Paramonov. Viable bacteria survived passage through the nematode and produced typical colonies on nutrient agar plates. Female nematodes ingested more bacterial cells and retained them longer than did males. It was hypothesized saprozoic nematodes may disseminate pathogenic bacteria to new infection courts.     

Viruses of Entamoeba histolytica IV. Studies on the Nucleic Acids of the Filamentous and Polyhedral Viruses

The nucleic acids of two amoebal viruses were studied by several independent methods. The filamentous virus, V(ABRM), was shown to be inhibited by bromodeoxyuridine, iododeoxyuridine, and cytosine arabinoside. With acridine orange staining, V(ABRM) inclusions appeared greenish-yellow, indicating that these contained double-stranded nucleic acid. The polyhedral virus, V(301), was also inhibited by bromodeoxyuridine, iododeoxyuridine, and cytosine arabinoside. In addition, nucleic acid hybridization showed that a new DNA species was synthesized in infected amoebal cultures. The intracellular localization of this new DNA was consistent with previous electron microscope studies of the cytoplasmic maturation of V(301).     

Viruses as triggers of autoimmunity: facts and fantasies.

Autoimmunity has been proposed as the cause of several human chronic inflammatory diseases, and recent animal studies show that viruses can induce autoimmune disease. These studies demonstrate how viruses might misdirect the immune system, and here we discuss critically the evidence that similar phenomena may lead to human disease.     

Studies on the biochemical basis of spontaneous mutation. V. Effect of temperature on mutation frequency

Temperature, in the range of 15 °C to 40 °C, has a pronounced effect on the incorporation of 2-aminopurine deoxynucleotides into DNA by purified bacteriophage T4-induced DNA polymerase. Whereas the total rate of utilization of the 2-aminopurine deoxynucleoside triphosphate increases with increasing temperature, a greater proportion is converted to the monophosphate by the editing nuclease of the enzyme. Therefore, the amount of analogue incorporated goes through a maximum and then decreases with increasing temperature. These results, obtained in vitro, have been correlated with effects of temperature on 2-aminopurine induced and spontaneous mutation rates of several rII markers, and they have been generalized to an hypothesis which holds that the stability of the helix immediately preceding the incoming nucleotide is an important factor in determining the accuracy of DNA replication. We suggest that there is a higher probability of making errors via base substitutions in a more stable (G + C-rich) rather than a less stable (A + T-rich) microenvironment.