Use of immunoreactive synthetic HTLV-1 peptides in the search for antibody reactivity in multiple sclerosis

The possible association between multiple sclerosis (MS) and antibodies to human T-cell lymphotropic virus type 1 (HTLV-1) was studied. Five synthetic and highly immunoreactive HTLV-1 peptides, four from the envelope (env) region and one from the core (gag) region, were used in an indirect enzyme-linked immunosorbent assay (ELISA). Presence of HTLV-1-specific antibodies in paired serum and cerebrospinal fluid (CSF) samples from 41 MS patients were investigated. No antibody reactivity was demonstrable in samples from 40 of them, whereas one reacted in one serum sample against the gag-peptide. Serum and CSF specimens from 15 with other neurologic diseases (OND), and negative control specimens, i.e. serum and CSF from 9 non-neurologic controls and CSF from 9 healthy controls, did not demonstrate any reactivity in the peptide-ELISAs. Our results do not support involvement of HTLV-1 infection in the etiology of MS.

Immunizations of monkeys with synthetic peptides disclose conserved areas on gp120 of human immunodeficiency virus type 1 associated with cross-neutralizing antibodies and T-cell recognition

Site-directed immunization was employed to identify sites on the envelope glycoprotein gp120 for antibody-mediated neutralization of human immunodeficiency virus type 1 (HIV-1). Antisera were raised in monkeys (Macaca fascicularis) against a series of 40 overlapping synthetic peptides covering the entire amino acid sequence of gp120 from the HTLV-IIIB strain of HIV-1. Immune sera against 12 of these peptides were reactive with gp120 by immunoblotting analysis, and antisera raised against 5 peptides, corresponding to amino acids (aa) 152-176, 193-218, 206-230, 248-269, and 307-330, were highly efficient in neutralizing HIV-1 (HTLV-IIIB) infectivity in vitro. Admixture of individual neutralizing anti-peptide monkey sera resulted in increment in neutralizing antibody titer. Antisera with reactivity to the relatively conserved regions defined by aa 152-176, 193-230, and 248-269 also neutralized to different extents the infectivity of the five Swedish clinical isolates of HIV-1 tested. Only a few HIV-1-infected people were found to make antibodies to these three conserved domains of gp120 as judged by ELISA using synthetic peptides as antigens. Three of the peptides (aa 152-176, 248-269, and 307-330) that induced neutralization antibodies also induced interleukin 2 production and lymphocyte proliferation when added to cultures of peripheral blood mononuclear cells from monkeys immunized with the corresponding peptides, indicating that these domains accommodate T-cell recognition sites. The results have obvious implications for the rational design of subunit vaccines against HIV-1 infection.

Involvement of glycoprotein C (gC) in adsorption of herpes simplex virus type 1 (HSV-1) to the cell

Results demonstrating involvement of glycoprotein C (gC) of herpes simplex type 1 virus (HSV-1) in attachment of the virus to the cell are presented. Monoclonal antibodies against gC-1 inhibited adsorption of gC(+)-strains. The gC(-)-mutant, MP, attached to cells but at a reduced rate. Attachment of the MP-mutant was unaffected by presence of anti-gC-1 antibody. Purified truncated gC-1 adsorbed to cells at a rate essentially the same as that of gC(+)-virus. Glycoprotein C-1 pretreated with heparin did not adsorb to cells. The results are compatible with a suggested role for gC in HSV attachment.

Identification of type-specific linear epitopes in the glycoproteins gp46 and gp21 of human T-cell leukemia viruses type I and type II using synthetic peptides

Synthetic peptides of 20-25 amino acids were employed in enzyme-linked immunosorbent assays to identify linear epitopes in the external glycoprotein gp46 and the transmembrane glycoprotein gp21 of human T-cell leukemia/lymphotropic viruses type I (HTLV-I) and II (HTLV-II). Ten linear epitopes were identified in the HTLV-I glycoproteins, seven in gp46 and three in gp21. Three major linear epitopes were identified in the gp46 of HTLV-II. Peptides representing linear epitopes of gp46 were found to be sensitive and specific for the detection of antibody and permit serological identification and differentiation of HTLV-I and HTLV-II infections.

Binding of herpes simplex virus to cellular heparan sulphate, an initial step in the adsorption process

It has been suggested that heparan sulphate has a receptor function in the initial phase of the attachment of herpes simplex virus (HSV) to cells. We have studied the influence of glycosaminoglycans on cell adsorption of, and plaque formation by, HSV-1 and HSV-2, with regard to the role of saccharide structure, chain length and charge density. Heparin and highly-sulphated heparan sulphate (1.5 sulphate groups/disaccharide unit), but neither chondroitin sulphate nor dermatan sulphate, were found to compete with the cellular receptor for attachment of HSV. Heparan sulphate preparations of low sulphate content (0.5 and 0.7 sulphate groups/disaccharide unit) failed to show any significant interaction with HSV. Oligosaccharides generated by partial deaminative cleavage of heparin were used to determine the minimum molecular size required for the binding of virus; the smallest oligosaccharide which reacted with HSV was composed of 10 monosaccharide units. The importance of charge density was demonstrated more directly by subfractionation of the heparin dodecasaccharide fraction by anion-exchange HPLC. The virus-binding capacities of the four resulting dodecasaccharide subfractions increased from the least sulphated to the most heavily sulphated fraction. The results reported are discussed in relation to virus-receptor interactions involved in the attachment of HSV, including the reported binding of HSV to the fibroblast growth factor receptor.

Continuous epitopes of the human immunodeficiency virus type 1 (HIV-1) transmembrane glycoprotein and reactivity of human sera to synthetic peptides representing various HIV-1 isolates

Immunoreactive regions of human immunodeficiency virus type 1 (HIV-1) gp41 were mapped by reacting HIV-1 antibody-positive human sera with overlapping synthetic peptides which covered the transmembrane protein. Three immunoreactive domains were identified, and five different and partially overlapping epitopes recognized by HIV-1-positive human sera were found within one immunodominant region. The effect on antibody recognition after single amino acid substitutions within one defined epitope was also studied. The reactivity of various HIV-1-positive sera to synthetic peptides with amino acid substitutions representing known isolates suggests an important substitution in the major epitope of African HIV-1 strains.

Discrimination of herpes simplex virus types 1 and 2 cerebral infections in a rat model

A rat model was used to evaluate intertypic differences after intracranial (i.c.) inoculation of herpes simplex virus (HSV) types 1 and 2 strains with regard to neurovirulence and neuropathology, and influence of age on susceptibility. In adult rats, HSV-1 strains were more virulent than HSV-2 strains. HSV-1 replicated to higher titers in the central nervous system (CNS) of rats, as compared with HSV-2. In rats of less than 2-3 weeks of age, HSV-1 and HSV-2 were equally virulent, but morphological examination of rat brains showed type-specific differences in pathology and viral distribution already at the early postnatal stage. After HSV-1 infection, neuronal infection of the hippocampus, followed by cortical infection and edematous destruction dominated, while a preponderance of meningitis and invasive encephalitis was seen after HSV-2 infection. We suggest that the rat might be a useful model for human HSV infection in the CNS with discrimination between HSV-1 and HSV-2 infections, also at the early postnatal stage.

Effect of zidovudine on cerebrospinal fluid in patients with HIV infection and acute neurological disease

Two cases of HIV infection associated with neurological complications are described. The patients had been followed with repeated cerebrospinal fluid (CSF) analyses 1-3 years before the neurological disease and 5 months after zidovudine treatment. CSF mononuclear cell count and the AIDS predictors beta 2-microglobulin and neopterin decreased in CSF after treatment and were lower or at the level seen 1-3 years before treatment. The results suggest that zidovudine has a suppressive effect on the HIV infection in CNS at least for 5 months, even when low zidovudine doses (500 mg daily) were used.

Neurovirulence of herpes simplex virus types 1 and 2 isolates in diseases of the central nervous system

Herpes simplex virus (HSV) isolates derived from the central nervous system of ten patients with HSV-1-induced encephalitis, one patient with multiple sclerosis, and 14 patients with HSV-2-induced meningitis were investigated for neurovirulence by assaying the LD50 after nose and intracerebral (i.c.) inoculation of mice. HSV-1 encephalitis strains were significantly more virulent after nose inoculation (i.e. neuroinvasive) when compared with HSV-1 isolates from patients with oral lesions only, whereas HSV-2 meningitis strains were significantly more virulent after i.c. inoculation when compared with HSV-2 isolates from patients with genital lesions only. No correlation between high neurovirulence (defined as low LD50 for both routes of infection) and replication in cell cultures of neuronal and non-neuronal cell lines was found, but the weakly neurovirulent HSV-1 strain isolated from a patient with multiple sclerosis gave low replication yields. After nose inoculation, a highly neuroinvasive HSV-1 laboratory reference strain replicated to high titers in nose tissue, the trigeminal ganglia and brainstem, while a strain with low neuroinvasiveness but high i.c. virulence replicated less well in the brainstem. Neuroinvasiveness of the virus strain might be one factor of relevance in the pathogenesis of HSV-1 encephalitis in man.

Acyclovir concentrations in serum and cerebrospinal fluid at steady state

A long-term clinical trial of acyclovir, 800 mg tid, as a therapeutic agent in multiple sclerosis (MS) is in progress. In three patients paired serum and cerebrospinal fluid (CSF) specimens were sampled after one, four, eight and twelve months of continuous treatment. These samples were collected 1.5 h before or 1.5 h after an oral dose. Acyclovir concentrations were assessed by radioimmunoassay. In the CSF, the acyclovir concentration was relatively stable, with a mean of 0.83 microM, while the serum acyclovir concentration was variable with mean peak and trough concentrations of 4.08 and 2.47 microM, respectively. In two other MS patients the acyclovir concentration time profile in serum and CSF was studied at steady state during the 8 h dose interval. In this study the acyclovir concentration in the CSF was only slightly affected by the fluctuations in serum and the acyclovir CSF/acyclovir serum ratio was apparently not influenced by the blood-brain barrier function. We found no indication of an accumulation of acyclovir in cerebrospinal fluid after one to twelve months of oral treatment.

Herpes simplex virus infection of the rat sensory neuron. Effects of interferon on cultured cells

Embryonic rat dorsal root ganglion neurons were cultured in a two-chamber system allowing infection of neuritic extensions without exposure of neuronal cell bodies or vice versa. Herpes simplex virus type 1 was used to infect interferon-alpha and -beta treated or untreated neurons and the production of virus and interferon was assayed. Treatment of nerve cell bodies with interferon inhibited virus replication in a dose-dependent manner, whether virus was inoculated directly onto the nerve bodies or peripherally on the neuritic extensions. In contrast no antiviral effect was noted when neurities were treated with interferon suggesting possible lack of interferon receptors on neurites. On infection with herpes simplex virus the rat sensory neuron cultures did not produce interferon in amounts above the detection limit (0.5 units per ml) of the interferon assay used.

Herpes simplex virus infection of the human sensory neuron. An electron microscopy study

Herpes simplex virus (HSV) type 1 was used to infect cultures of human embryonic dorsal root ganglion cells. Infected cultured were studied by electron microscopy. Viral nucleocapsids were observed to be internalized into neuronal cells bodies and neuritic extensions by fusion of the viral envelope and the plasma membrane. No signs of internalization by endocytosis were noted. Nucleocapsids were transported in neurites and were within 2 hrs postinfection found located near the microtubules and close to the nuclear pores in the perikaryon. A primary envelopment of nucleocapsids occurred at the inner lamina of the nuclear membrane and virions appeared between the two laminae. Presence of non-enveloped nucleocapsids outside the nuclear membrane and in close contact with the endoplasmic reticulum suggested that nucleocapsids could pass to the cytoplasmic side probably by de-envelopment at the outer nuclear membrane. A secondary envelopment occurred at the endoplasmic reticulum where the virions also became enclosed in transport vesicles. Enveloped virus appearing in the cytoplasm of neurons and neuritic extensions was always found only inside these transport vesicles. During their passage through the cytoplasm the virion-transport vesicle complexes were surrounded by smaller lysosome-like vesicles possibly derived from the Golgi apparatus. Fusion reactions between vesicles with virions and the smaller vesicles seemed to occur. We discuss if in this way the virion-transport vesicle complexes might be provided with glycosyl transferases and substrates necessary for maturation and completion of glycosylation of the viral envelope glycoproteins. The transport vesicles seemed essential for egress of virions from the infected cell by releasing virus when fusing with the plasma membrane.

Prevalence of herpes simplex virus type 2 antibodies in selected population groups in Italy

The estimated prevalence of herpes simplex virus type-2 specific antibodies was less then 0.1% in a national sample of 1,169 healthy young males, 4.8% among 411 health care workers and 55% among 397 homosexuals. These viral infections seem to pose a health problem for risk groups such as homosexuals but not for the general population.

Long-term twice-daily oral acyclovir therapy suppresses frequently recurrent genital herpes

The efficacy of oral acyclovir in a twice-daily treatment regime was demonstrated in an open long-term study in 8 patients with frequently relapsing genital herpes type II infections. The treatment was well tolerated and no side effects were noted during the medication period of 6-21 months. No signs of decreased sensitivity for acyclovir appeared.

Neuritic transport of herpes simplex virus in rat sensory neurons in vitro. Effects of substances interacting with microtubular function and axonal flow [nocodazole, taxol and erythro-9-3-(2-hydroxynonyl)adenine]

Herpes simplex virus type 1 and a fluorescein-labelled lectin (wheat germ agglutinin) were selectively transported to nerve cell bodies located in the inner compartment of a two-chamber tissue culture system after the application of virus or lectin to the neuritic processes in the outer culture compartment. Taxol, which stabilizes and alters intracellular arrangements of microtubules, and nocodazole, which disrupts microtubules, both inhibited this retrograde axonal transport of viral particles and lectin. The transport was also inhibited by erythro-9-3-(2-hydroxynonyl)adenine (EHNA), which blocks ATPases. However, EHNA was also an effective inhibitor of infection with the virus in non-neuronal cells (GMK AH-1). The nature of the action(s) of EHNA on neuritic transport of the virus is therefore less clear.

Herpes simplex virus infection in capsaicin-treated mice

Following inoculation into the snout herpes simplex virus (HSV) spread to neurons in mouse trigeminal ganglion and subsequently to the brain. Capsaicin treatment of neonatal mice, which causes a loss of unmyelinated sensory neurons, some of which contain substance P, reduced the mortality rate of HSV-infected mice. Moreover, a lower percentage of mice survived the infection with reactivatable virus. There was also an extensive infection of glial cells proximal to the transitional zone in the trigeminal root between the peripheral and central nervous system. Distal to this zone there was an accumulation of substance P immunoreactivity in centrally directed fibres. This amplified degenerative effect on central branches of the substance P containing sensory nerves by glial infection may contribute to the deafferentiation pain syndrome following HSV infection.

Asymptomatic virus shedding in men with genital herpes infection

13 men with a history of recurrent genital herpes simplex virus type 2 (HSV-2) infection were followed daily for 4 weeks with samples taken from the urethra for virus isolation. Asymptomatic virus shedding occurred in 5 men who had 1 single positive isolation each. Four of these urethral isolates were typed as HSV-1 and 1 as HSV-2.

Neuritic uptake and transport of antiviral drugs modifying herpes simplex virus infection of rat sensory neurons

The neuritic uptake and transport of three antiviral drugs were studied in a cell culture system with dissociated cells of rat dorsal root ganglia. Cultured sensory neurons extended neuritic projections which penetrated a vacuum grease sealed diffusion barrier in the culture. The peripheral infection with herpes simplex virus (HSV) type 1 (McIntyre) resulted in uptake and transport of HSV by neuritic extensions causing a neuronal infection inside the diffusion barrier. By varying the route of administration and concentration of drug and by manipulating the nerve cell culture system, neuritic uptake and transport also of the antiviral drugs (acyclovir, adenine-arabinoside and foscarnet) were demonstrable. The findings are discussed in relation to axonal transport and antiviral treatment of HSV infections of the nervous system.

Inhibition of herpes simplex virus replication by tobacco extracts

Herpes simplex virus type 1 (HSV-1) has been associated with the genesis of leukoplakias, epithelial atypia, and oral cancer. Tobacco habits, such as snuff dipping, are also definitely correlated with this type of lesion. The normal cytolytic HSV-1 infection can, after in vitro inactivation, transform cells. Extracts of snuff were prepared and assayed for their ability to inhibit HSV-1 replication. Plaque formation assays of HSV-1 in the presence of snuff extract showed that a reduced number of plaques was formed. Different batches of one brand of snuff were tested for inhibition of herpes simplex virus (HSV) production. More than 99% inhibition of 24-hr HSV production was obtained with undiluted batches. The 1:5 dilutions of snuff had an inhibitory effect of 85% and 1:25 dilutions, 39%. In agreement, the attachment of the virus to the host cell and penetration of the virus to the cell nuclei were found to be inhibited as was the synthesis of viral DNA. Nicotine had an inhibitory effect, while aromatic additions to snuff were found to have no major inhibitory effect on HSV replication. Snuff extracts were prepared from different brands of snuff reported to contain high and low quantities of tobacco-specific N-nitrosamines. Brands with reported high levels of tobacco-specific N-nitrosamines had significantly greater ability to inhibit HSV replication. In conclusion, this study has shown that extracts of snuff have inhibitory effects on the production of cytolytic HSV-1 infections. A chronic snuff dipper keeps tobacco in the mouth for the major part of the day. Thus, virus shed in the oral cavity in connection with a reactivated latent HSV-1 infection has great possibilities of being affected by snuff or derivatives of snuff. It is suggested that an interaction between tobacco products and HSV-1 might be involved in the development of dysplastic lesions in the oral cavity.

Herpes simplex virus type-selective enzyme-linked immunosorbent assay with Helix pomatia lectin-purified antigens

Helix pomatia lectin-purified antigens with specific reactivity to herpes simplex virus type 1 (HSV-1) and HSV-2 antibodies in human sera were used in an enzyme-linked immunosorbent assay. The type specificity of the antigens was assessed by double immunodiffusion precipitation in gel against rabbit HSV-1 and HSV-2 hyperimmune sera, and by enzyme-linked immunosorbent assay with human reference sera containing antibodies to either type of HSV. Fifty-two sera from patients with documented infection with either HSV-1 or HSV-2 were assayed for HSV type-specific immunoglobulin G antibodies. The reactivity of the sera against lectin-purified antigens correlated completely with the results of virus typing. We conclude that HSV type-specific immunoglobulin G antibodies can easily be measured by enzyme-linked immunosorbent assay with the use of Helix pomatia lectin-purified HSV-1 and HSV-2 antigens.

Uptake and transport of herpes simplex virus in neurites of rat dorsal root ganglia cells in culture

Attachment and neuritic transport of herpes simplex virus (HSV) type 1 (McIntyre) were studied in a cell culture system with dissociated cells of rat dorsal root ganglia. The two-chamber cell culture system containing a diffusion barrier penetrated by neurites of cultured sensory neurons permitted infection of neurites extending outside the diffusion barrier without exposure of the neuronal cell soma. HSV adsorbed to neuritic extensions and reached the neuronal soma within 1.5 h post-inoculation. Neuritic uptake and transport of HSV were inhibited in the presence of cytochalasin B. Internalization of virus in neurites was preceded by attachment of virus to the neurite plasma membrane. Neurites transported viral nucleocapsids (NC) through the diffusion barrier of the cultures. Destruction of the neuritic extensions before or shortly after peripheral virus inoculation blocked spread of infection to the cell soma. No infection was established when neuritic extensions were exposed to viral NC and NC were then not observed inside the neurite plasma membrane. Virus produced in neurons, when HSV was inoculated into the inner culture chamber containing the neuronal cell bodies, was transported as enveloped virus in cytoplasmic vesicles from the neuronal cell body towards the periphery. Schwann cells were infected by viropexis. Shortly after infection virions were observed in vacuoles of the cytoplasm.

Evaluation of solubilized herpes simplex virus membrane antigen by enzyme-linked immunosorbent assay

An antigen prepared by solubilization of membranes from herpes simplex virus (HSV)-infected cells with deoxycholate was evaluated by enzyme-linked immunosorbent assay. The deoxycholate-solubilized antigen, previously shown to contain all major HSV glycoproteins, was noninfectious and adsorbed easily and reproducibly to a polystyrene surface at pH 9.6. The deoxycholate-solubilized antigen provided an enzyme-linked immunosorbent assay of high sensitivity and reproducibility with complete correlation with complement fixation for the diagnosis of acute HSV infection. The correlation with neutralization and immunofluorescence for the presence or absence of anti-HSV activity was very good. Comparison with an HSV envelope preparation yielded results slightly in favor of the deoxycholate-solubilized antigen. The assay seems to be useful for demonstration of intrathecal production of antibody activity in HSV encephalitis.

Herpes simplex virus-induced demyelination. Effects of reinfection and challenge with neuroantigens

Mice injected into the snout with the F-strain of herpes simplex virus (HSV) showed demyelination in the central part of the trigeminal root and brainstem. In this well characterized model the effect of reinfection with a virulent strain of HSV, and of immunization with UV-light-inactivated HSV and neuroantigens were examined. A marked enhancement of demyelination was found in mice immunized with spinal cord extracts in Freund's adjuvant prior to the HSV infection. Whether this effect is mediated by a general stimulation of inflammatory or immune competent cells or is dependent upon exposure to specific antigens is not known.

Early interactions of herpes simplex virus with mouse peritoneal macrophages

Adsorption of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) to resident peritoneal macrophages (PM) of 4-week-old Swiss albino (SA) and GR/AFib mice was studied. A significantly (P less than 0.05) higher HSV-2 adsorption rate was found with PM of SA mice than with PM of GR/AFib mice. Of added HSV-2 65% bound to the cells of SA mice over a 120-min period versus 15% to PM of GR/AFib mice. Only 15 to 20% of added HSV-1 bound to PM regardless of the mouse strain. These patterns of adsorption were found with all four HSV-1 and four HSV-2 strains tested. Pretreatment of PM with an HSV-2 mutant blocked the adsorption of added HSV-2. Thus, the receptors for HSV attachment seemed to be virus type selective. To avoid masking of adsorption by phagocytotic activity, the adsorption studies had to be performed at 4 degrees C. Transport of attached HSV-1 and HSV-2 to the nuclei of SA PM was studied with purified virus labeled with 32Pi and [3H]thymidine. In double-isotope experiments, only transport of HSV-2 was detected. The possible importance of differences in density or avidity of virus-binding receptors on the plasma membrane of PM is discussed in relation to macrophage-dependent focal liver necrosis, which was only demonstrable after intraperitoneal inoculation of HSV-2, not HSV-1, only in SA, not GR/AFib, mice.

Virus-induced demyelination in herpes simplex virus-infected mice

Herpes simplex virus (HSV) infection of the mouse trigeminal ganglia and the brain stem is associated with demyelination of axons in the central part of the trigeminal root and inflammatory cell infiltration and perivascular demyelination in the brain stem. Cyclophosphamide (CPA) treatment prior to or soon after HSV inoculation caused increased axonal spread of infective virus from the peripheral site of inoculation, more widespread and severe demyelination and increased mortality, suggesting that by CPA the virus invasion of the CNS was facilitated. A direct cytocidal effect of HSV on myelinating cells seemed one plausible explanation for the demyelination. Influence on demyelination at late stages of infection by cytotoxic immune reactions are not excluded by the results reported but seemed not to dominate the picture. Schwann cells from the peripheral part of the nerve root invaded demyelinated areas in the brain stem and remyelinated the axons.

Multiplicity activation of herpes simplex virus in mouse neuroblastoma (C1300) cells

The virus yields and number of infectious centres of HSV infected mouse neuroblastoma C1300 cells (clone 41 A3) infected at different multiplicities of infection (MOI) were found to vary more than the differences of HSV concentrations of the virus suspensions used for infection of the cells. This suggested that a C1300 cell had to be infected with more than one HSV particle in order to produce progeny virus-multiplicity activation. The greater than expected enhancement of virus production of C1300 cell cultures receiving increasing MOI of HSV was probably not due to improved virus adsorption, nor influenced by non-virus factors in the virus inoculum stimulatory for HSV replication. A hypothesis, that the block in virus replication was promoted by an inhibitor of an HSV specified regulatory protein and could be overcome by the addition of HSV DNA copies in the infected cell, was by the results of two types of experiments. Presence of phosphonoformic acid, an inhibitor of the HSV specified DNA polymerase, in the culture medium of HSV infected permissive GMK cells resulted in non-linear relationships between virus yields and MOI. An HSV temperature sensitive mutant (ts B5), defective in a late structural protein, rescued wild type HSV in C1300 cells.

Antibody responses to live and killed poliovirus vaccines in the milk of Pakistani and Swedish women

The effect of poliovirus vaccination on mucosal immunity was studied in lactating women because secretory IgA antibodies to poliovirus in milk may reflect intestinal immunity. Swedish mothers lacked significant titers of secretory IgA antibodies in their milk before vaccination. Subcutaneous vaccination with killed poliovirus vaccine resulted in low but transient increases in titers of secretory IgA antibodies in the milk of most of these women. Pakistani mothers had significant titers of secretory IgA antibodies in their milk before immunization; these titers increased after subcutaneous poliovirus vaccination in 45% of the women. Peroral vaccination of Pakistani women with liver poliovirus vaccine diminished already existing titers of secretory IgA antibodies in their milk. The decrease in titer was especially pronounced when the liver poliovirus vaccine was given together with a subcutaneous vaccine consisting of killed Vibrio cholerae organisms; the mean titer of secretory IgA antibodies in milk 14 days after vaccination was about 40-fold lower than it was before vaccination.

Persistent reactivable latent herpes simplex virus infection in trigeminal ganglia of mice treated with antiviral drugs

Latent reactivable infection was established with HSV in mouse trigeminal ganglion. A number of antiviral drugs (IUDR, acycloguanosine, Ara-A, PAA and PFA), effective against acute CNS infection with HSV, failed to influence the latent infection once established. Neither lipophilic properties of PFA-derivatives nor the combination of Ara-A and acycloguanosine improved the drug-effects on HSV latency.

Differences in attachment between herpes simplex type 1 and type 2 viruses to neurons and glial cells

Fractions of nerve cell perikarya, synaptosomes, and astrocytic glia were prepared from human, monkey , rabbit, rat, and mouse brain tissue. The herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) binding capacity of these fractions was studied. Pretreatment of fractions with one type of HSV and the subsequent testing of adsorption of homotypic and heterotypic virus ws employed to reveal type selectivity of virus binding receptors. A higher density of HSV-1 than of HSV-2 selective receptors was found on synaptosomes and glial cells, except with mouse-derived preparations. Synaptosomal and glial cell preparations of mouse brains adsorbed both types of HSV well. Little or no adsorption was observed with HSV-1 and HSV-2 to neuronal perikarya. The type selectivity of HSV binding receptors on brain cells ws demonstrated on preparations of human synaptosomes and mouse glial cells. Some possible implications of the observations on the HSV infection of the nervous system are discussed.

Separation of herpes simplex virus virions and nucleocapsids on Percoll gradients

Herpes simplex virus (HSV) virions and nucleocapsids were separated and purified by centrifugation in density gradient of polyvinylpyrrolidone-coated colloidal silica (Percoll). Virions and nucleocapsids banded at densities of 1.07 and 1.03 g/ml, respectively. The distribution in the gradient of virions and nucleocapsids suggested that particles were discriminated according to difference in size rather than in density. The reduction of cell proteins in preparations of purified virions was 1300--2100 times. The recovery of infective virus was approximately 30%.

Latent herpes simplex virus trigeminal ganglionic infection in mice and demyelination in the central nervous system

Mice were inoculated with herpes simplex virus (HSV) type 1 by gently scraping the skin of the nose with a fine needle. About 80% of the animals developed latent inapparent HSV infections in trigeminal ganglia. Virus was demonstrable for at least 6 months post inoculation (p.i.) by cocultivation of ganglionic tissue with GMK cells. Histologically, trigeminal ganglia revealed infiltrations of inflammatory cells even 6 months p.i. In addition, lesions occurred in the brainstem corresponding to the entry of trigeminal roots, trigeminal tracts and nuclei. Inflammatory cell infiltration, disruption of myelin sheaths and macrophages laden with myelin degradation products were observed 7 days p.i. Fourteen to 30 days p.i. electron microscopy demonstrated completely naked axons. In the transitional region of the trigeminal root denuded axons occurred in the central part of the region while the peripheral myelin, bordering the demyelinated central segments, was intact. Small areas of demyelination were still detectable 3 and 6 months p.i. but there were then also signs of remyelination. Possible mechanisms causing the demyelinations are discussed.

Evidence for herpes simplex virus type-selective receptors on cellular plasma membranes

Herpes simplex virus type 1 (HSV-1) interfered with the adsorption of subsequently added homotypic but no heterotypic HSV, suggesting that the cellular receptors involved were type-selective. Both infective and u.v.-irradiated virus could block the attachment of virions to cellular surface receptors. The adsorption rate was studied by assaying non-adsorbed infective virus remaining in the fluid medium and cell-associated 3H-thymidine labelled HSV, and HSV mutants assayed in presence of phosphonoformic acid (PFA). The adsorption profiles indicated that GMK AH-1, Vero and SIRC cells all exhibited more HSV type 1-than type 2-selective receptors while HeLa S3 cells displayed more receptors with affinity for type 2 than for type 1. On HEp-2 and human embryonic lung cells HSV type 1- and type 2-selective receptors were about equally represented.

Immune reactivity of Visna virus-inoculated mice

Visna virus inoculation of mice before immunization with unrelated antigens caused suppression of humoral and cell-mediated immune responses. The immunosuppressive effect was dependent on the virus dose and time of administration. The number of "background" antibody-producing spleen cells increased slightly after inoculation of Visna virus. Heat treatment of Visna virus abolished its immunosuppressive effect. Replication of Visna virus in mice seemed to be a prerequisite for its immunomodulating effect.

Tumor incidence in Visna virus inoculated mice

Mice (female Swiss albino) inoculated when newborn with Visna virus had tumors in 77% of cases when examined 8-12 months later. The tumors were mainly of the mammary carcinoma type. The tumor incidence in non-infected control animals was only 20%. In contrast, no increased incidence of tumors was observed among Visna virus-inoculated inbred mice (BALB/c, CBA and DBA) with low incidence of spontaneous mammary carcinoma.