Biomedical subjects
Publications and source records attributed to W A Blyth.
Acyclovir (ACV) was effective in preventing recurrence of herpes simplex in mice whose skin was stripped with cellophane tape. Treatment with ACV did not eliminate latent herpes simplex virus from the cervical ganglia.
Mice latently infected with herpes simplex virus were treated with immunosuppressive drugs either alone or combined with stimuli to the skin. Treatment with cyclophosphamide reduced spleen weights and severely depressed lymphocyte levels, but had no effect on healing after cellophane tape stripping (CTS) and did not affect the cutaneous hypersensitivity response after injection of inactivated herpes simplex virus. The drug, either used alone or combined with CTS, failed to increase the incidence of recurrent clinical disease, but increased the incidence of virus isolation after CTS. Prednisolone and azathioprine used together also reduced spleen weights and circulating lymphocyte levels. They slightly delayed healing after CTS, but had no effect on cutaneous hypersensitivity to herpes simplex virus. The treatment, either used alone or combined with CTS, slightly increased the incidence of recurrent clinical disease but did not increase the incidence of virus isolation after CTS. Treatment with antithymocyte serum severely depressed the levels of circulating lymphocytes and delayed the regression of HeLa cell tumors in mice. Used alone, the treatment slightly increased the incidence of recurrent clinical disease, but it failed to increase the incidence of recurrences after CTS. It increased the duration of recurrent herpetic lesions, although in uninfected mice healing after CTS was not affected. Silica altered the clinical course of primary infection with herpes simplex virus and increased the incidence of latency in the ganglia. It also delayed healing after CTS in uninfected mice, so it was not tested when recurrent herpes after CTS was assessed clinically. Treatment with silica alone did not increase the incidence of recurrent clinical disease or the incidence of virus isolation after CTS. The results demonstrate that potent immunosuppressive drugs are much less effective than simple cutaneous manipulation in inducing recurrent lesions, and thus argue strongly for the importance of local factors in the pathogenesis of disease.
Mild trauma was induced in the skin of mice latently infected with herpes simplex virus type I by stripping the originally infected ear with cellophane tape. Recurrent herpes simplex developed at this site 2 to 5 days later. It was detected clinically by the development of erythema and vesicles and by the appearance of virus in the skin. On any one occasion about 30% of mice showed reactivated disease and increasing the severity of trauma did not increase this proportion. However the majority of animals developed reactivated disease on some occasions when stripping was repeated at monthly intervals. The results are discussed in relation to the skin trigger theory of reactivation of herpes simplex.
Stimuli such as u.v. light or trauma which induce recurrence of herpes simplex may act by affecting virus replication in the skin. Such stimuli release pharmacologically active agents in the skin, including prostaglandins (PGs) such as PGE2. These agents, and other compounds which alter levels of adenosine cyclic monophosphate (cyclic AMP), were tested for their effect on the replication of herpes simplex virus (HSV) in Vero cells. Prostanglandin E2 (PGE2) and prostaglandin F2alpha both increase the size of HSV plaques; PGE2 also increases the yield of virus inoculated at low m.o.i. Moreover, inhibitors of prostanglandin synthesis decrease plaque size and inhibit the growth of virus inoculated at low m.o.i.; such inhibition can be partially overcome by adding PGE2. Analysis of the results suggest that prostaglandins can enhance cell-to-cell spread of HSV, but that cyclic AMP is probably not involved in this effect.
The effect of irradiation with UV light on herpes simplex virus infection in the mouse ear was investigated. Irradiation 2 days before infection had no effect on the titre of virus in the skin 3 days after infection. In ears irradiated 24 hours or immediately before infection virus titres measured 3 days after infection were depressed. Irradiation 2 days after infection enhanced virus titres. The dose of irradiation used did not directly inactivate herpes simplex virus in the ear. The results are discussed with reference to theories of herpes simplex reactivation.
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Reactivation of herpes-simplex is thought to require stimulation of latent virus in the sensory ganglion before the virus travels to the skin and causes a lesion. An alternative theory is proposed whereby virus is often released from the ganglion to form microfoci of infection in the skin but these are usually eliminated. Physiological changes in the skin, perhaps induced by prostaglandins, occasionally allow lesions to develop.
Herpes simplex infection in the mouse ear was used to investigate whether various treatments would reactivate the disease. Immunosuppressive drugs failed to induce clinical signs of reactivation but irradiation of the skin of the originally infected ear with ultraviolet light or injection of prostaglandin E2 or PBSA into this site, caused reactivation of infection. This was detected by the appearance of infectious virus in the skin 2 to 3 days after these treatments. The results are discussed in relation to the mechanism of herpes reactivation in man.
Nineteen recent isolated and three laboratory strains of herpes simplex virus types 1 and 2 were tested for their ability to produce clinical signs in mice following intradermal inoculation in the ear. All viruses produced erythema at the inoculation site; this was the most sensitive clinical sign of infection. Virus multiplication in the ear tissue was similar for both types 1 and 2 up to the fifth day after inoculation but type 2 viruses persisted for longer. Latent infection was demonstrated in cervical dorsal root ganglia. Type 1 viruses required a much higher dose than type 2 to produce neurological signs and death after intradermal inoculation but the difference was less after intracerebral inoculation. Erythema of the inoculated ear recurred sporadically during several months observation in about half the mice that survived intradermal infection with a selected type 1 isolate. The presence of virus in the ear tissue during such recurrences was confirmed by electron microscopy and isolation of infectious virus. The system of ear infection in the mouse is presented as a new model for studying neurovirulence, and latent and recurrent infection with herpes simplex virus.
BHK-21 cells and HeLa cells were as sensitive as irradiated McCoy cells for titrating both fast- and slow-growing strains of TRIC agents. BHK-21 cells were as efficient as irradiated McCoy cells for isolating TRIC agents from trachoma and from the genital tract of patients with non-gonococcal urethritis. More inclusions were formed in BHK-21 than in irradiated McCoy cells.
The neutralizing activities of fowl, rabbit and mouse antisera prepared against TRIC agents were enhanced, in some cases over a 100-fold, by the addition of antiserum against the appropriate IgG. Significant non-specific inactivation of the organisms was observed in the absence of antiserum against TRIC agents, in reaction mixtures containing normal serum and antiserum against IgG. Since the extent of this inactivation showed a prozone, control tests with dilutions of normal serum equivalent to the full range of dilutions of the antiserum tested are necessary to show that enhancement of neutralization is specific.
TWO CHANGES WERE OBSERVED IN THE ACID PHOSPHATASE OF MACROPHAGES THAT HAD INGESTED INFECTIVE TRIC ORGANISMS: the proportion of extralysosomal enzyme rose, while the total amount in the cells fell. Both effects were directly related to the number of organisms ingested and increased with time. When macrophages were inoculated with more than 50 organisms per cell, changes were obvious within a few hours; with 2-10 organisms per cell changes were detectable only after 18 hr. or more. Enzyme appeared in the culture medium as the amount in the cells decreased. Ingestion of organisms killed by heat or treated with antibody did not induce such changes. In infected BHK-21 cells, no changes in acid phosphatase were detected at any stage of the developmental cycle of the organism.
TRIC agents do not multiply in mouse peritoneal macrophages in culture but have a toxic effect on them, whereas they multiply readily in BHK-21 cells. Sections of macrophages and of BHK-21 cells fixed during the first 90 min after inoculation were examined by electron microscopy. Macrophages ingested all forms of the organism, which were eventually degraded in lysosomes. However, elementary bodies were distinguished from other TRIC particles by the delay in their transfer to lysosomes. BHK-21 cells ingested elementary bodies selectively, and in these cells the organisms were neither found in lysosomes nor degraded. Instead they showed morphological changes that probably represented an early stage of development.
In BHK 21 cells infected with more than one TRIC organism the inclusions coalesce so that 30 hr. after infection only one inclusion per cell remains. Six hours after infection the cells are as susceptible to further infection as uninfected cells.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.