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Biomedical subjects

W A Blyth

Publications and source records attributed to W A Blyth.

At least 19 recordsLinked to original sources
PubMed1992

Experimental in vivo generation of intertypic recombinant strains of HSV in the mouse.

The primary replication of one strain of HSV was generally unaffected by the simultaneous inoculation of another strain either at the same site or at a different site within the same dermatome. Exceptions to this were the result of the generation of intertypic recombinants which were readily isolated only from sensory ganglia 5 and 6 days after inoculation with a mixture of HSV-1 and HSV-2 and from explant culture of the resultant latently infected ganglia. By restriction enzyme analysis the majority of the recombinant strains from primary infection were characterized as HSV 1; all those from latently infected ganglia were characterized as type 2.

Animals↗
PubMed1990

Heterotypic and homotypic re-inoculation of mice already latently infected with herpes simplex virus type 1.

Mice were infected at 4 weeks of age with a type 1 strain of herpes simplex virus (HSV) and re-infected 4 weeks later with either a type 1 or a type 2 strain of HSV. The virus used for first infection could be distinguished from that used later since it was resistant to phosphonoformic acid and formed syncytial plaques. Sites used for the second inoculation were as follows: at the site of primary infection, at a different site within the same dermatome or in the equivalent dermatome on the opposite side (also called "remote" site). Re-infection caused no detectable reactivation of the latent PFA resistant virus. After re-infection with a homotypic virus replication of the re-infecting virus was limited to the inoculation site. However after heterotypic re-infection the type 2 strain was occasionally isolated from the ganglia. Previous infection with the PFA resistant type 1 strain clearly reduced the ability of the homotypic or heterotypic strains to establish a latent infection. However, in a few animals ganglia were found to be latently infected with virus from both the first and second inoculations. Analysis of the results suggests that resistance to the establishment of a second latent infection in a ganglion is determined by the general immunity of the animal rather than "immunity" of the latently infected ganglion itself.

Animals↗
PubMed1990

Possible latent infection with herpes simplex virus in the mouse eye.

Herpes simplex virus (HSV) was isolated from organ cultures of anterior segments of the eyes of mice inoculated with virus on the snout or directly onto the cornea at least 5 weeks previously. The frequency of isolation of the virus was not decreased by treatment of the animals with acyclovir, suggesting that the virus is latent by the criteria usually applied. Peroxidase-antiperoxidase staining of organ cultures that had shed virus showed that viral antigens were predominantly present in the anterior uvea. Inoculation of mouse eye anterior segments in vitro showed that this tissue was the most susceptible to productive infection. These results suggest the possibility that HSV can establish a latent infection in tissues of the anterior segment of the mouse eye.

Acyclovir↗
PubMed1990

Reactivation of latent infection and induction of recurrent herpetic eye disease in mice.

During primary ocular infection of mice with herpes simplex virus type 1 (HSV-1) strain McKrae, dendritic corneal ulcers developed and many eyes became permanently damaged. When primary infection had subsided, latent infection was detected in the three parts of the trigeminal ganglion and in the superior cervical ganglion. Such latently infected mice were treated with cyclophosphamide, dexamethasone and u.v. irradiation, or cyclophosphamide and dexamethasone alone. After treatment with immunosuppressive drugs and u.v. irradiation infectious virus was isolated from the ophthalmic part of the trigeminal ganglion, and in eyelids and eyewashings; recurrent herpetic eye disease was seen but only in eyes undamaged by primary infection. After treatment with cyclophosphamide and dexamethasone alone there was a lower incidence of virus isolated from eyewashings and no recurrent disease was seen. There was a good correlation between the pattern and distribution of recurrent lesions and the distribution of cells stained due to the presence of virus antigens.

Animals↗
PubMed1990

Passive immunization protects the mouse eye from damage after herpes simplex virus infection by limiting spread of virus in the nervous system.

Mice were treated with serum containing antibodies to herpes simplex virus type 1 (HSV-1) or normal serum, 1 day before inoculation on the cornea with HSV-1 strain McKrae. As expected, without passive immunization, mice developed high levels of serum neutralizing antibody. By contrast, in passively immunized animals, such antibody became undetectable by 29 days after inoculation of serum, in spite of the virus infection. There was no difference between passively immunized mice and those given normal serum in the duration of shedding of virus in tears and the duration and severity of corneal epithelial disease. However, non-immunized mice had a high incidence of mortality and developed disease of the iris, corneal stroma and lids, and their corneas became opaque and vascularized. In non-immunized animals, the timing of isolation of virus from nervous tissues and the sequence of appearance of virus antigens in ocular tissues indicate that the disease of deeper eye tissue was caused by virus spreading from the nervous system back to the eye. Restriction of such spread in passively immunized animals seems the likely explanation for their protection from death and severe ocular damage. Despite this restricted spread, passively immunized animals had a high incidence of latent infection in the ophthalmic part of the trigeminal ganglion. However, in comparison with mice given normal serum, there was a far lower incidence of such infection in the other two parts of this ganglion and in the superior cervical ganglion. Since passively immunized animals have a high incidence of latent infection in the ophthalmic part of the trigeminal ganglion and their eyes are normal, they will prove useful in studies involving induction of recurrent disease.

Animals↗
PubMed1989

Quantification of herpes simplex virus infection in cervical ganglia of mice.

Mice were inoculated with herpes simplex virus (HSV) type 1 in the skin of the neck. The extent of primary and latent infection in the second and third cervical ganglia was investigated. Immunoperoxidase staining of ganglia during primary infection demonstrated HSV antigens initially in a restricted area of the ganglion. By the 5th day after infection, antigen was more widespread. Such a change in the staining pattern is explicable in terms of the zosteriform spread of virus from neurons innervating the site of infection to others supplying other areas of the dermatome. A maximum of approximately 10% of neurons became infected. By the 7th day staining was limited to a few cells. During latent infection, enzymic disaggregation of ganglia followed by immunoperoxidase staining or infectious centre assay indicated that virus reactivation began within 30 h of removal of ganglia and occurred in approximately 1% of viable neurons.

Animals↗
PubMed1989

Detection of herpes simplex virus type 1 gene expression in latently and productively infected mouse ganglia using the polymerase chain reaction.

The polymerase chain reaction (PCR) was employed to detect herpes simplex virus (HSV) sequences in the DNA, and HSV gene expression in total cell RNA, extracted from cervical and trigeminal ganglia of mice during productive and latent infection with HSV-1, strain SC16. Such gene expression was detected in 1 microgram or less of RNA, the quantity anticipated to be present in one or two cervical ganglia. Within the limits of the primers available, gene expression during latency appeared to be restricted to the latency-associated transcript (LAT). The 195 base portion of the LAT amplified by the PCR was sequenced and found to contain several base changes and deletions with respect to published sequences for different HSV strains. These mutations, within the putative open reading frame 2 of the LAT, formed stop or terminator signals, which suggests that the LAT does not act to establish or maintain latency through translation to a protein. The primers for the LAT also amplified a 300 bp fragment from any murine and some other mammalian RNAs. Apart from the oligonucleotide primers, this fragment did not show any homology with HSV.

Animals↗
PubMed1987

Quantitative studies on Langerhans cells in mouse corneal epithelium following infection with herpes simplex virus.

Dendritic Langerhans cells (LCs) were identified in flat-mount preparations of mouse corneal epithelium after staining for ATPase activity. They were found predominantly in the limbus, but after inoculating the cornea with HSV1 strain SC16 LC, numbers increased both in the limbus and the central cornea. Numbers of LCs reached a maximum on day 8 and if severe keratitis was present remained high at least until day 22. A small but significant increase in LCs was also found in the opposite, uninoculated eye in mice with severe damage in the inoculated eye. After HSV inoculation on the snout, 60% of mice had corneal disease in the eye on the inoculated side; in such mice corneal LCs were at a maximum 18 days after inoculation. The increase in LC numbers was similar whether inoculation was into the cornea or in the snout. After corneal inoculation the cells were distributed fairly evenly over the corneal surface, with accumulations limited to epithelial ulcers. However, after inoculation on the snout, numerous clusters were seen over the epithelial surface, often surround by epithelium devoid of LCs.

Animals↗
PubMed1987

Does herpes simplex virus establish latency in the eye of the mouse?

Clinically scarred and neovascularised corneas observed after zosteriform spread of herpes simplex virus (HSV) to the eye of the mouse were found to contain chronic inflammatory cells with a loose retrocorneal membrane. Goblet cells were found in the corneal epithelium. The trigeminal ganglia of such animals were latently infected with HSV. Whereas HSV was not isolated from eye-washings of diseased eyes, it was isolated from some anterior segments after culture in vitro for up to 13 days. When anterior segments were halved sagittally, HSV could not be isolated from the halves assayed immediately, whereas it was isolated from some of the other halves after organ culture. The possibility of ocular latency is discussed.

Animals↗
PubMed1987

Spread of herpes simplex virus within ocular nerves of the mouse: demonstration of viral antigen in whole mounts of eye tissue.

Spread of herpes simplex virus to and within the mouse eye after inoculation of the cornea or the skin of the snout was examined by peroxidase-antiperoxidase (PAP) staining of viral antigen in flat mounts of the eye and by isolation of virus from nervous tissue. Following inoculation of virus at either site, viral antigen was found in ocular nerves. One to three days later antigen was also found in the iris, ciliary body and choroid/sclera suggesting that virus spread to these tissues occurred via their nerve supply. Viral antigen was also found in the retina of the uninoculated eye after corneal inoculation. After inoculation of the snout, virus was isolated from ophthalmic and maxillary parts of the trigeminal ganglion and the superior cervical ganglion and then from the brainstem, eye and mandibular part of the trigeminal ganglion. This sequence also suggested that virus reached the eye via the nerves and that this may occur indirectly via the brainstem. The PAP method allows rapid determination of the distribution of antigen in various tissues. Our observations suggest that widespread involvement of ocular tissue may occur by spread of virus in nerves within the eye.

Animals↗
PubMed1987

Restriction endonuclease analysis of herpes simplex virus from recrudescent lesions, from latent infection and during passage in the skin and nervous system of mice.

The stability of the restriction endonuclease profile of herpes simplex virus type 1 strain SC16 in mice was studied. Virus isolated from skin during acute infection was compared with that from latently infected ganglia and with that from recrudescent lesions induced by trauma. In another experiment virus serially passaged only in skin was compared with virus that had also replicated in the nervous system. The loss or gain of specific restriction sites was not observed but in some cases the mobility of certain fragments decreased.

Animals↗
PubMed1987

The influence of androgens on paralysis in mice following intravenous inoculation of herpes simplex virus.

In mice, intravenous inoculation of relatively avirulent strains of herpes simplex virus [e.g. P2C6, a mutant of strain CL(101), deficient in thymidine kinase] produced infection in the adrenal gland and mid-spinal cord followed by hind limb paralysis without death. Male mice were less susceptible to paralysis than female mice. Castration of male mice before inoculation increased their susceptibility to that of female animals; treatment with testosterone reversed this change. The differences in susceptibility to paralysis in the various categories of animal were not reflected in differences in growth of virus in the adrenal gland or spinal cord.

Adrenal Glands↗
PubMed1987

Spread of HSV-1 to the mouse eye after inoculation in the skin of the snout requires an intact nerve supply to the inoculation site.

Infection of the eye following inoculation of herpes simplex virus on the skin of the snout was monitored using slit lamp examination of the eye, isolation of virus from eyewashings and identification of virus antigens in whole corneal epithelial sheets by peroxidase-antiperoxidase staining. Infection of the eye was prevented by removing a section of the sensory nerves which supply the inoculation site. This provided evidence that spread from the skin of the snout to the eye occurred via the nerves.

Animals↗
PubMed1986

Antigens of herpes simplex virus in whole corneal epithelial sheets from mice.

Mice were inoculated with herpes simplex virus in the skin of the snout or by scarification on the cornea and then examined for eye disease using a slit lamp. Whole mounts of corneal epithelium were stained for virus antigens by the peroxidase-antiperoxidase method, and infectious virus was isolated from eyewashings. Antigens were present one day after corneal inoculation, but after inoculation of the snout, there was a delay of three days before antigens were seen. This delay and the distribution of antigens were evidence of zosteriform spread from the snout to the eye via the nervous system. Disease of the cornea varied in severity and timing depending on the site of inoculation. The peroxidase-antiperoxidase method was more sensitive than isolation of virus from eyewashings and allowed the site and distribution of infected cells to be seen.

Animals↗
PubMed1986

Infection of the adrenal gland as a route to the central nervous system after viraemia with herpes simplex virus in the mouse.

Intravenous inoculation of 4-week-old female NIH (inbred) mice with herpes simplex virus type 1 (HSV-1) strain P2C6 (defective in thymidine kinase) produced bilateral hind limb paralysis in nearly all animals by the 5th day after inoculation; very few mice died. In male mice the incidence and severity of paralysis was considerably lower than in females. The parental strain, CL(101), produced similar paralysis but all mice died by day 7. Observations on paralysis and death after intravenous inoculation are given for other strains of HSV-1 and HSV-2. By day 1 after inoculation of P2C6 significant virus replication had occurred in the adrenal glands but in none of the other organs tested. Titres of virus were similar in the adrenal glands of male and female mice. Histology of the adrenals showed most extensive replication in the cortex with some involvement of the medulla, particularly at the corticomedullary junction. By the 2nd and 3rd days, virus was detected in the lower thoracic spinal cord of both male and female animals but clearance was possibly quicker from males. Adrenalectomy proved that virus reached the cord via the adrenals. In the cord the infection was associated with bilateral demyelination in the ventral white matter as early as day 3.

Adrenal Gland Diseases↗
PubMed1985

Spread of herpes simplex virus and distribution of latent infection after intraocular infection of the mouse.

Intraocular inoculation of HSV 1 in the mouse results not only in uveitis, but also in the spread of virus via sensory, sympathetic and optic nerves. During the acute infection with HSV 1 strain SC 16 in both outbred and NIH (inbred) mice, virus reached the ipsilateral trigeminal ganglion, superior cervical ganglion, both sides of the brain stem and the contralateral (uninoculated) eye. With HSV 1 strain KOS in outbred mice the same tissues became infected but virus was also isolated from the ophthalmic part of the contralateral trigeminal ganglion. After resolution of the acute disease in outbred mice, latent infection with strain KOS was demonstrated in both trigeminal ganglia and in the ipsilateral superior cervical ganglion. With strain KOS, virus was sometimes isolated from eyes removed more than a month after inoculation and then cultured in vitro for 2-3 weeks. By electron microscopy infected cells were seen in the choroid and sclera of such eyes.

Animals↗
PubMed1985

Protection from herpes simplex virus-induced neuropathology in mice showing delayed hypersensitivity tolerance.

Herpes simplex virus (HSV)-susceptible mice inoculated under conditions favouring the preferential activation of T suppressor (Ts) cells acting on the delayed-type hypersensitivity (DTH) response to the virus were protected from lethal herpes encephalitis and from central nervous system (CNS) demyelination (as reflected by ear paralysis), compared to controls given normal priming. Thus, suppressed DTH was not incompatible with recovery from acute infection and may indeed have been beneficial. Protection could be transferred by T cells from donors given a 'DTH-tolerogenic' priming regime. It was unlikely that protection resulted from enhancement of other mechanisms such as cytotoxic T cell activation, antibody or interferon production, since no reduction of virus spread was observed in protected mice. In addition, several aspects of Ts cell activation by intravenous inoculation of avirulent HSV type 1 have been characterized. Suppression was virus dose-dependent and could be transferred to the efferent limb of a DTH response. Activation of Ts cells for DTH coincided with an enhanced antibody response. It is suggested that protection in this model may be mediated by Ts cells which act to limit DTH-mediated immunopathology in the CNS.

Animals↗