Simultaneous measurement of antibodies to Epstein-Barr virus, human herpesvirus 6, herpes simplex virus types 1 and 2, and 14 enteroviruses in chronic fatigue syndrome: is there evidence of activation of a nonspecific polyclonal immune response?

As a test of the hypothesis that elevated titers of viral antibodies in patients with chronic fatigue syndrome (CFS) are due to a nonspecific polyclonal immune response, antibodies to Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and 14 enteroviruses in 20 patients with CFS and 20 age- and gender-matched controls were simultaneously measured. Similarly, titers of IgG to herpes simplex virus (HSV) types 1 and 2 were measured in 18 of these cases and in the respective controls. IgG to EBV viral capsid antigen (VCA) was present at titers > or = 1:320 in 55% of cases vs. 15% of controls (P = .02). The geometric mean titers of early antigen antibody to EBV, HHV-6 IgG, and HSV-1 and HSV-2 IgG were not significantly different among cases and controls. Of the 14 enteroviral antibodies tested for, only those to coxsackieviruses B1 and B4 were present at significant titers (> or = 1:8) in cases vs. controls (P = .02 and P = .001, respectively). Of the cases, 19 (95%) had either an EBV VCA IgG titer > or = 1:320 or a coxsackievirus B1 or B4 antibody titer > or = 1:8, a percentage significantly higher than that of controls (40%; P = .0004). Titers of EBV VCA IgG and coxsackievirus B1 and B4 antibodies were simultaneously elevated in only 20% of cases. There was no correlation between elevated titers of EBV VCA IgG and IgG to HHV-6, HSV-1, and HSV-2 or antibody to coxsackieviruses B1 and B4 in the cases. The prevalence of reported allergies to medications or other substances was identical in both groups (60%). These findings suggest that in the majority of cases of CFS, elevation of viral antibody titers is not due to a nonspecific polyclonal immune response.

Induction in vitro of primary cytotoxic T-lymphocyte responses with DNA encoding herpes simplex virus proteins

Vaccines which successfully protect against virus infections usually need to induce a broadly reactive immune response which includes the induction of cytotoxic T lymphocytes (CTL). In this study, we have used a convenient in vitro approach to investigate if plasmid DNAs encoding proteins of herpes simplex virus (HSV) are capable of inducing primary CD8+ CTL. Dendritic cells or macrophages were transfected with either plasmid DNA encoding glycoprotein B or DNA encoding the immediate-early protein ICP27. These antigen-presenting cells (APC) were then used to stimulate enriched populations of naive T cells in microcultures for 5 days in vitro. Antigen-specific CD8+ CTL which reacted both with specific protein-expressing targets and with syngeneic targets infected with HSV could be demonstrated. Dendritic cells, as APC, generated the maximal responses, but such cells needed to be transfected with DNA in the presence of a cationic lipid. However, macrophages could act as APC when they were exposed to purified DNA. HSV-primed splenocytes were also shown to generate specific CTL responses when they were stimulated with purified DNA encoding ICP27. The novel approach described in this paper promises to be extremely useful, since defining immunogenicity profiles and identifying epitopes on viral proteins should be easier and more convenient when working with DNA and investigating variables in vitro. This is particularly the case with complex viruses such as HSV, most of whose encoded proteins have yet to be isolated in sufficient quantity or purity to perform in vivo immunological studies.

Ectopic expression of gamma interferon in the eye protects transgenic mice from intraocular herpes simplex virus type 1 infections

Transgenic (rho gamma) mice provide a model for studying the influence of gamma interferon (IFN-gamma) produced in the eye on ocular and cerebral viral infection. To establish this model, we injected BALB/c- and C57BL/6-derived transgenic and nontransgenic mice of different ages intravitreally with herpes simplex virus type 1 (HSV-1) strain F. Eye and brain tissues of these mice were assessed for pathological and immunocytochemical changes. HSV-1 infection induced severe retinitis of the injected eyes and infection of the brain in all mice. In transgenic mice inoculated with HSV-1, the left, nontreated eyes were protected from retinitis, whereas nontransgenic mice developed bilateral retinitis. Additional intravitreal injection of IFN-gamma with the virus protected the noninoculated eyes of nontransgenic mice. Three-week-old nontransgenic mice died from HSV-1 infection, whereas transgenic mice of the same age and nontransgenic mice intravitreally treated with IFN-gamma survived. Ocular IFN-gamma production increased the extent of inflammation in transgenic mice but did not have a significant influence on the growth of HSV-1 until day 3 after inoculation and did not influence the neuroinvasion of this virus. Thus, the effects of IFN-gamma were not caused by an early block of viral replication. Possible mechanisms of IFN-gamma action include activation of the immune response, alteration of the properties of the virus, and direct protection of neurons.

Similar immune response to nonlethal infection with herpes simplex virus-1 in sensitive (BALB/c) and resistant (C57BL/6) strains of mice

Previous investigations have demonstrated a strain-associated differential susceptibility to herpes simplex virus-1 (HSV-1) infection in mice; C57BL/6 mice are more resistant to infection than BALB/c mice. Despite considerable research dealing with the immune response to HSV-1, relatively little attention has been paid to differences in immune responses between strains with different sensitivities to the virus. Here we report that immune responses (i.e., cytokine profiles, CTL activity, serum antibody, and natural killer cell activity) following footpad infection with a sublethal dose of HSV-1 do not substantially differ between the two strains. It is notable that C57BL/6 mice are also more resistant than BALB/c mice to other pathogens, including Leishmania, and this resistance is associated with a predominant TH1 response in C57BL/6 mice versus a predominant TH2 response in BALB/c mice. However, unlike several other pathogens, the increased susceptibility to HSV-1 infection of BALB/c mice, compared to C57BL/6 mice, does not appear to involve an obvious difference in the TH1 vs TH2 dominance of the immune response to this virus.

Transformed cells producing the glycoprotein D of HSV-1 are resistant to infection with clinical strains of HSV

The generality of the resistance exhibited by gD producing cells to HSV-1 infection was tested. We tested three different cell lines producing various amounts of gD for resistance against three HSV-1 strains. The strains used were the prototype laboratory F strain and two recently isolated low passage local clinical strains, VG and VD. The results indicate that: (i) the resistance of the cell lines is directly related to the amount of gD they produce, (ii) the cell lines showed greater resistance against the two local clinical HSV-1 strains than against the laboratory strain, and (iii) the resistance is not mediated at the level of virus adsorption to the cell membranes.

Inflammatory effects of gene transfer into the CNS with defective HSV-1 vectors

The use of viral vectors which infect and express genes in post-mitotic neurons is a potential strategy for the treatment of disorders affecting the central nervous system (CNS). However, the inflammatory consequences of such strategies have yet to be systematically examined. Preparations of non-replicating defective herpes simplex virus type 1 (HSV-1) amplicon vectors containing the lacZ gene were obtained by standard methods and stereotaxically injected into the adult rat dentate gyrus (DG). The consequent gene expression and inflammatory effects following microinjection were investigated. beta-Galactosidase activity was detected in neurons of the DG from 24 h to at least 12 days after vector injection. A strong inflammatory response developed within 2 days, characterized by diffuse up-regulation of major histocompatibility complex (MHC) class I antigens and the activation of microglia. After 4 days the recruitment of MHC class II+ cells, activated T lymphocytes and macrophages was detected. These features persisted for at least 31 days. Of importance was the finding of beta-galactosidase activity in a bilateral group of neurons in the supramammillary nuclei (SMN) of the posterior hypothalamus, known to send afferent projections to the DG. The onset of inflammation at this secondary site was delayed, but its cellular characteristics resembled those found at the primary site of injection. Thus, the use of preparations of defective HSV-1 vectors for gene transfer in the CNS has immunological implications both at primary and secondary sites within the CNS.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of B lymphocytes in experimental herpes simplex viral retinitis

The purpose of this study was to examine B cell participation in experimental herpes simplex virus (HSV) retinitis. Passive immunization with anti-herpes antibody protects BALB/c mice from herpes simplex retinitis (HSR). Using anti-Mu antibody treatment, we modified the B cell population of C.B-17 mice, normally resistant to HSR, in order to test the hypothesis that such treatment would render them susceptible to HSR by impairing their early antibody response to anterior chamber (AC) inoculation with HSV. We analysed the effect of anti-Mu treatment on their susceptibility to HSR and then employed Polymerase Chain Reaction (PCR) and ELISA techniques to study the patterns of immunoglobulin gene and protein expression, and the T-cell receptor alpha/beta (TCR alpha/beta) gene expression after AC inoculation of HSV. Immunohistopathologic analysis revealed that 100% of the B cell deficient mice (B-) developed contralateral retinitis following AC inoculation, confirming the hypothesis that anti-Mu antibody treatment would convert HSR-resistant mice into HSR-susceptible ones. Transfer of B cells from naive congenic donor mice resulted in 67% of recipient B- mice developing contralateral retinitis. Transfer of anti-HSV antibody conferred nearly complete protection, with only 11% of mice developing retinitis (P < 0.005). PCR and ELISA analysis showed that both untreated and B- C.B-17 mice showed similar dynamic patterns of mRNA IgG isotype expression and of anti-HSV IgG isotypic antibody response following AC inoculation. Thus, we were forced to reject the hypothesis that an impaired early antibody response is primarily responsible for the increased HSR susceptibility seen in B- mice. In contrast, PCR analysis of TCR alpha/beta mRNA expression revealed dramatic differences between susceptible and resistant mice, suggesting that TCR V beta selection and usage may be a critical factor influencing HSR-sensitivity in this murine model, and that B cells (and immunoglobulin isotype) may play a role in TCR V beta selection and usage after ocular encounter with HSV.

Cervical antibodies in patients with oral herpes simplex virus type 1 (HSV-1) infection: local anamnestic responses after genital HSV-2 infection

Herpes simplex virus (HSV)-specific immunoglobulin A, immunoglobulin G, and secretory-component-containing immunoglobulins were identified in cervical and salivary secretions from six subjects with oral HSV type 1 (HSV-1) infections. Anamnestic cervical and salivary antibody responses were detected in two HSV-1-seropositive women with newly acquired genital HSV-2 infections. These data implicate the common mucosal immune system in antibody responses to HSV.

Rapid diagnosis of cutaneous herpes simplex infections using specific monoclonal antibodies

One hundred children with suspected herpes simplex virus (HSV) infection and 20 controls were studied to compare a rapid immunofluorescence (RIF) test for detection and typing of HSV from smears of lesions with standard viral culture. The RIF test was evaluated for ease of use and speed of diagnosis. RIF and/or culture were positive in 64% of patients. All infections diagnosed by RIF and culture were HSV type 1. In 92% of patients RIF and culture results were in concordance. In 57 cases, RIF and cultures were positive for HSV infection and in 35 cases RIF and cultures were negative for HSV infection. Three patients had inadequate samples for RIF and five children had positive RIF but were culture negative. All controls had negative results both by RIF test and culture. The RIF test demonstrated 100% sensitivity and 95% specificity. The RIF test was type specific, easy to perform and gave diagnosis of HSV infections within an hour of taking the clinical specimen. This study suggests the RIF test is as good, if not more sensitive, in the diagnosis of HSV infections as standard viral culture and has the advantage of speed of diagnosis.

Corneal donor infection by herpes simplex virus: herpes simplex virus DNA in donor corneas

Three corneoscleral discs (from two donors) underwent subtotal endothelial loss during routine "long-term" organ culture storage. Laboratory studies of these corneas revealed evidence of herpes simplex virus (HSV) infection. The fellow cornea from one of the donors had been issued for transplant to a patient with keratoconus. Deterioration of the graft was noted 5 days after surgery; the disc was removed at 2 months and was shown to be infected with HSV. In an experiment designed to simulate initial "cleansing" of donor globes, 0.1% polyvinylpyrolidone-iodine protected cells from infection with HSV. It was concluded that the detection of HSV in these corneas could not be explained by external contamination of the ocular surface. Furthermore, culture of conjunctival and pharangeal swabs taken from 47 consecutive donors confirmed that HSV is rarely isolated at or around the time of death. Five pairs of donor corneas destined for use in transplantation were selected at random and investigated for the presence of HSV. HSV DNA was detected by polymerase chain reaction (PCR) in tissue from two of the corneal donors. Sequential stepwise sectioning suggested that HSV DNA when present was distributed in discrete foci within the cornea. These observations suggest that HSV infection may be a cause of severe endothelial loss during corneal organ culture and possibly provide an explanation for some "failures" of corneal grafting.

The immune response and the eye: the ACAID inducing signal is dependent on the nature of the antigen

PURPOSE

To examine conditions that determine the nature of the blood-borne, ACAID-inducing signal produced after intracameral injection of antigen.

METHODS

Balb/c mice were splenectomized, rested, and injected in the anterior chamber with various antigens. Two days later the animals were bled, the plasma and white cells were isolated, and these fractions were transferred to naive mice (with spleens). Recipients were immunized subcutaneously within 2 to 7 days and delayed type hypersensitivity was assessed 10 to 14 days after immunization by challenge with the appropriate antigen.

RESULTS

The antigens HSV-1, TNP-coupled cells, and P815 tumors cells induced a soluble ACAID-inducing signal found in the plasma portion of blood. The soluble protein antigens bovine serum albumin (BSA) and conalbumin induced a cell-associated signal. When T-cells were included with protein antigens, a soluble (not cellular) ACAID-inducing signal was induced.

CONCLUSIONS

Particulate antigens, such as HSV-1 and P815, that elicit intraocular T-cell responses or antigens that contain T-cells (e.g., TNP cells) induce a soluble, ACAID-inducing signal. Soluble antigens (e.g., BSA and conalbumin) induce a cell-associated ACAID signal. Additionally, T-cells are capable of modulating the type of ACAID signal produced. These results show that two methods of delivering the ACAID signal exist that are dependent on the nature of the antigen and the presence of T-cells. The authors conclude that the eye shows great versatility in regulating potentially damaging immune responses.

Infection and inhibition of human cytotoxic T lymphocytes by herpes simplex virus

The effect of herpes simplex virus type 1 (HSV-1) infection on human cytotoxic T-lymphocyte (CTL) lytic function was assessed. All HSV-infected CTL populations tested were significantly inhibited in lysing target cells. The inhibition of CTL lytic function by infection with HSV-1 was independent of T-cell receptor-mediated antigen recognition and did not involve virus-induced shutoff of host protein synthesis, the expression of the HSV-1 transactivation protein, ICP4, or replicating virus. Understanding the functional impairment of CTL following infection with HSV may have important implications for HSV-induced immunosuppression and the mechanism of HSV persistence in immunocompetent hosts.

[An experimental study on cultivation of human trigeminal ganglionic cell in vitro and its sensitivity to infection of herpes simplex virus type 1]

We firstly report an experimental study on the sensitivity of primary cultural human trigeminal ganglionic cells infected by herpes simplex virus type 1 (HSV-1) in different time-points. The results indicate that the neuron of human trigeminal ganglia is the most sensitive cell type, the antigen of HSV-1 replicates rapidly within the cytoplasm and cell nucleus, the fibroblasts and glia cells are infected partly by the virus. Therefore, perhaps the neuron is the main harboring cell type.

Selected epidemiological features of herpes genitalis in Israel based on laboratory data

The incidence in Israel of genital infection with herpes simplex virus (HSV) has been increasing steadily over the last two decades. During the years 1973-91, 1,508 patients had an HSV infection confirmed by viral culturing. The yearly incidence of new cases rose from sporadic cases in the seventies to 32.4 cases per 1,000 patients in 1990. The age distribution pattern did not change since 1980 and showed a peak incidence in subjects aged 20-40 years. The increase of HSV type 2 (HSV-2) infection rate in the Israeli population, as judged from specific geometric mean titers (GMT), rose from 15.25 in 1970 to 89.3 in 1991, while the GMT for HSV type 1 (HSV-1) did not increase significantly. The incidence of HSV-2 positive subjects (HSV-2/HSV-1 antibody ratio > or = 1) was low in the Jewish Israeli population, compared to other demographic areas. The predominant type of genital infection was HSV-2, although 21% of genital isolates were HSV-1.

The role of natural killer cells in the development of herpes simplex virus type 1 induced stromal keratitis in mice

Natural killer (NK) cells and acquired cell-mediated immunity effector cells (delayed type hypersensitivity (DTH) and cytotoxic T lymphocytes (CTL)) have been reported to play a vital role in the defence of the host against tumour and viral infections in locations other than the eye. A vigorous cellular inflammatory response to viral infections of the cornea, however, with the attendant damage to the corneal clarity, has obvious evolutionary disadvantages, and a substantial body of evidence indicates that in animals (e.g. mice) which are highly susceptible to inflammatory destruction of the cornea following corneal encounter with herpes simplex virus, it is the animal's immunological/inflammatory response which is responsible for the corneal damage. We examined the role of natural killer cells in the development of herpes stromal keratitis (HSK) in NK-deficient (C57BL/6J-bgj (beige)) mice and their NK-competent (C57BL/6J (black) relatives. The beige (NK-deficient) mice were just as resistant to HSK as were the black mice. We also studied the effects of NK cell depletion of BALB/c Igh-1 disparate congenic mice. C.AL-20 (Igh-1d) mice are ordinarily highly susceptible to necrotising HSK. In vivo NK-cell depletion in these mice significantly decreased the incidence and severity of HSK in these animals (p < 0.0005). Corneas from untreated C.AL-20 mice contained T cells, macrophages and NK cells. The corneal infiltrate from NK-depleted C.AL-20 mice consisted of T cells and macrophages but no NK cells. These data indicate that NK cells are participants in the development of HSK in the murine model of this disease.

[In vivo observations and electron microscopy in the treatment of experimental HSV keratitis with monoclonal antibodies]

In vivo observations and electron microscopy showed that topical use of anti-HSV monoclonal glycoprotein antibodies produced marked antiviral effects in inhibiting the development of experimental herpetic keratitis in rabbits and in protecting the susceptible corneal cells. As a new biological product, the anti-HSV monoclonal antibodies may provide a new approach to the treatment of HSV keratitis.

[The production of recombinant polypeptides from the herpes simplex viruses types 1 and 2]

The genes IE175, IE63, IE68, IE12, UL29 and UL19 of herpes simplex virus types 1 and 2 were cloned. Fragments of these genes were cloned into open reading frame expression vector pEX1-3. Recombinant proteins containing amino acid sequences of ICP4, ICP27, ICP22, ICP47, major DNA-binding protein and major capsid protein were expressed in E. coli cells by fusion with cro-beta-galactosidase proteins.

A vaccinia virus--herpes simplex virus (HSV) glycoprotein B1 recombinant or an HSV vaccine overcome the HSV type 2 induced humoral immunosuppression and protect against vaginal challenge in BALB/c mice

Primary infections with herpes simplex virus type 2 (HSV-2) suppress the antibody response to secondary HSV-1 and -2 infections in the BALB/c mouse. In contrast, a challenge by the i.p. route using a vaccinia virus-HSV-1 glycoprotein B (VV gB1) recombinant induces a significant enhancement of the antibody response. This booster reaction is also observed if a challenge with a formalin-inactivated HSV-1 vaccine is performed. Although no or low humoral and vaginal antibodies are detectable after a single i.p. infection with the VV gB1 recombinant or the HSV-1 vaccine, protection against vaginal challenge with HSV-2 is induced. This points to the important role of cellular immunity for vaginal infections.

Antigenic specificities of human CD4+ T-cell clones recovered from recurrent genital herpes simplex virus type 2 lesions

Lesions resulting from recurrent genital herpes simplex virus (HSV) infection are characterized by infiltration of CD4+ lymphocytes. We have investigated the antigenic specificity of 47 HSV-specific CD4+ T-cell clones recovered from the HSV-2 buttock and thigh lesions of five patients. Clones with proliferative responses to recombinant truncated glycoprotein B (gB) or gD of HSV-2 or purified natural gC of HSV-2 comprised a minority of the total number of HSV-specific clones isolated from lesions. The gC2- and gD2-specific CD4+ clones had cytotoxic activity. The approximate locations of the HSV-2 genes encoding HSV-2 type-specific CD4+ antigens have been determined by using HSV-1 x HSV-2 intertypic recombinant virus and include the approximate map regions 0.30 to 0.46, 0.59 to 0.67, 0.67 to 0.73, and 0.82 to 1.0 units. The antigenic specificity of an HLA DQ2-restricted, HSV-2 type-specific T-cell clone was mapped to amino acids 425 to 444 of VP16 of HSV-2 by sequential use of an intertypic recombinant virus containing VP16 of HSV-2 in an HSV-1 background, recombinant VP16 fusion proteins, and synthetic peptides. Each of the remaining four patients also yielded at least one type-specific T-cell clone reactive with an HSV-2 epitope mapping to approximately 0.67 to 0.73 map units. The antigenic specificities of lesion-derived CD4+ T-cell clones are quite diverse and include at least 10 epitopes. Human T-cell clones reactive with gC and VP16 are reported here for the first time.

Characterization of domains of herpes simplex virus type 1 glycoprotein E involved in Fc binding activity for immunoglobulin G aggregates

Herpes simplex virus type 1 glycoproteins gE and gI form receptors for the Fc domain of immunoglobulin G (IgG) which are expressed on the surface of infected cells and on the virion envelope and which protect the virus from immune attack. Glycoprotein gE-1 is a low-affinity Fc receptor (FcR) that binds IgG aggregates, while gE-1 and gI-1 form a complex which serves as a higher-affinity FcR capable of binding IgG monomers. In this study, we describe two approaches used to map an Fc binding domain on gE-1 for IgG aggregates. First, we constructed nine plasmids encoding gE-1/gD-1 fusions proteins, each containing a large gE-1 peptide inserted into the ectodomain of gD-1. Fusion proteins were tested for FcR activity with IgG-sensitized erythrocytes in a rosetting assay. Three of the fusion proteins containing overlapping gE-1 peptides demonstrated FcR activity; the smallest peptide that retained Fc binding activity includes gE-1 amino acids 183 to 402. These results indicate that an Fc binding domain is located between gE-1 amino acids 183 and 402. To more precisely map the Fc binding domain, we tested a panel of 21 gE-1 linker insertion mutants. Ten mutants with insertions between gE-1 amino acids 235 and 380 failed to bind IgG-sensitized erythrocytes, while each of the remaining mutants demonstrated wild-type Fc binding activity. Taken together, these results indicate that the region of gE-1 between amino acids 235 and 380 forms an FcR domain. A computer-assisted analysis of the amino acid sequence of gE-1 demonstrates an immunoglobulin-like domain contained within this region (residues 322 to 359) which shares homology with mammalian FcRs.

Regions US6 and US7 of herpes simplex virus type 1 DNA encoding glycoproteins D and I may influence neuroinvasivity

Recombinants were prepared by replacing a 1931 bp region of the BamHI J fragment (0.906-0.920) of the pathogenic ANGpath DNA-coding for glycoprotein D (gD) and a part of glycoprotein I (gI)--by the corresponding sequence of nonpathogenic KOS DNA (Kaerner et al., 1991) and tested in DBA/2 mice. The strain ANGpath and the control recombinant ANGpath/gD-gIpath, prepared by back transfer of the given ANGpath DNA fragment into ANGpath/gD-gIdellacZ+ DNA, were pathogenic after intraperitoneal inoculation. In contrast, mice infected with the strain KOS and the low-pathogenic recombinant ANGpath/gD-gIKOS survived peripheral virus administration. Both the strain KOS and the low-pathogenic recombinant ANDpath/gD-gIKOS spread by bloodstream to spleen, liver and adrenal glands but did not multiply in spinal cord. Nevertheless, the antigen of low-pathogenic recombinant ANGpath/gD-gIKOS was found in retroperitoneal vegetative nerves and ganglia. On the other hand, the strain ANGpath and the pathogenic recombinant ANGpath/gD-gIpath multiplied in cerebrospinal nerves and spinal cord causing typical hind leg paralysis.

Expression of seven herpes simplex virus type 1 glycoproteins (gB, gC, gD, gE, gG, gH, and gI): comparative protection against lethal challenge in mice

We have constructed recombinant baculoviruses individually expressing seven of the herpes simplex virus type 1 (HSV-1) glycoproteins (gB, gC, gD, gE, gG, gH, and gI). Vaccination of mice with gB, gC, gD, gE, or gI resulted in production of high neutralizing antibody titers to HSV-1 and protection against intraperitoneal and ocular challenge with lethal doses of HSV-1. This protection was statistically significant and similar to the protection provided by vaccination with live nonvirulent HSV-1 (90 to 100% survival). In contrast, vaccination with gH produced low neutralizing antibody titers and no protection against lethal HSV-1 challenge. Vaccination with gG produced no significant neutralizing antibody titer and no protection against ocular challenge. However, gG did provide modest, but statistically significant, protection against lethal intraperitoneal challenge (75% protection). Compared with the other glycoproteins, gG and gH were also inefficient in preventing the establishment of latency. Delayed-type hypersensitivity responses to HSV-1 at day 3 were highest in gG-, gH-, and gE-vaccinated mice, while on day 6 mice vaccinated with gC, gE, and gI had the highest delayed-type hypersensitivity responses. All seven glycoproteins produced lymphocyte proliferation responses, with the highest response being seen with gG. The same five glycoproteins (gB, gC, gD, gE, and gI) that induced the highest neutralization titers and protection against lethal challenge also induced some killer cell activity. The results reported here therefore suggest that in the mouse protection against lethal HSV-1 challenge and the establishment of latency correlate best with high preexisting neutralizing antibody titers, although there may also be a correlation with killer cell activity.

Characterization of baculovirus-expressed herpes simplex virus type 1 glycoprotein K

The DNA region encoding the complete herpes simplex virus type 1 (HSV-1) glycoprotein K (gK) was inserted into a baculovirus transfer vector, and recombinant viruses expressing gK were isolated. Four gK-related recombinant baculovirus-expressed peptides of 29, 35, 38, and 40 kDa were detected with polyclonal antibody to gK. The 35-, 38-, and 40-kDa species were susceptible to tunicamycin treatment, suggesting that they were glycosylated. The 38- and 40-kDa species corresponded to partially glycosylated precursor gK (pgK) and mature gK, respectively. The 29-kDa peptide probably represented a cleaved, unglycosylated peptide. The 35-kDa peptide probably represented a cleaved, glycosylated peptide that may be a precursor to pgK. Indirect immunofluorescence with polyclonal antibody to gK peptides indicated that the recombinant baculovirus-expressed gK was abundant on the surface of the insect cells in which it was expressed. Mice vaccinated with the baculovirus-expressed gK produced very low levels (< 1:10) of HSV-1 neutralizing antibody. Nonetheless, these mice were partially protected from lethal challenge with HSV-1 (75% survival). This protection was significant (P = 0.02). Despite some protection against death, gK-vaccinated mice showed no protection against the establishment of latency. Surprisingly, gK-vaccinated mice that were challenged ocularly with a stromal disease-producing strain of HSV-1 had significantly higher levels of ocular disease (herpes stromal keratitis) than did mock-vaccinated mice. In summary, this is the first report to show that vaccination with HSV-1 gK can provide protection against lethal HSV-1 challenge and that vaccination with an HSV-1 glycoprotein can significantly increase the severity of HSV-1-induced ocular disease.

Replacement of glycoprotein B gene in the herpes simplex virus type 1 strain ANGpath DNA by that originating from nonpathogenic strain KOS reduces the pathogenicity of recombinant virus

Herpes simplex virus type-1 (HSV-1) strain ANGpath and its recombinants, in which the 8.1 kbp BamHI G restriction fragment (0.345-0.399) containing the glycoprotein B (gBpath) gene (UL27) or its subfragments-coding either for cytoplasmic or surface domains of gB-had been replaced with the corresponding fragments from nonpathogenic KOS virus DNA (gBKOS), were tested for their pathogenicity for DBA/2 mice and rabbits. The recombinant ANGpath/B6KOS prepared by transferring the 2.7 kbp SstI-SstI subfragment (0.351-0.368) of the BamHI GKOS fragment still had the original sequence of ANGpath DNA coding for the syn3 marker in the cytoplasmic domain of gB and was pathogenic for mice as well as for rabbits. Virological and immunohistological studies in DBA/2 mice infected with the latter pathogenic recombinant and with ANGpath showed the presence of infectious virus and viral antigen at inoculation site (epidermis, subcutaneous connective tissue and striated muscle in the area of right lip), in homolateral trigeminal nerve and ganglion, brain stem, midbrain, thalamic and hypothalamic nuclei. In contrast, nonpathogenic recombinants ANGpath/syn+B6KOS (prepared by transferring the whole BamHI GKOS fragment) and ANGpath/syn+KOS (prepared by transferring the 0.8 kbp BamHI-SstI subfragment of the BamHI GKOS fragment) showed limited haematogenous and neural spread, but no evidence of replication in CNS; thus, their behaviour resembled that of the wild type strain KOS. The recombinant ANGpath/syn+KOS, which was not pathogenic for mice, still remained pathogenic for rabbits, a phenomenon indicating the presence of an additional locus in the gB molecule participating on virulence. Sequencing the 1478 bp SstI-SstI subfragment of the BamHI G(path) fragment (nt 53,348-54,826 of UL segment) showed the presence of at least 3 mutations as compared to the KOS sequence, from which the change of cytosine to thymine at nt 54,251 altered the codon for arginine to that for histidine (amino acid 515) in the gB polypeptide chain.

Stochastic curtailing and conditional power in matched case-control studies

New methodology for early stopping of observational epidemiologic studies is developed. To indicate the likelihood of a positive result at the end of a study, the conditional power (CP) is calculated using an approach similar to that of Halperin et al. Given the current result, the conditional probability of a positive result for the entire study is determined. An expression relating the new approach to an approach given by Lan and Wittes is derived. As an example, the CP is calculated based on information from the first third of a matched case-control study embedded in an epidemiological study.

Human fetal antibody-dependent cellular cytotoxicity to herpes simplex virus-infected cells

Human fetal antibody-dependent cellular cytotoxicity (ADCC) has not been reported previously. Most investigations have failed to document any cytolytic activity among fetal lymphocytes. The purpose of this study was to investigate ADCC activity in the human fetus and identify and characterize the effector cell populations in the fetus. Fetal spleen cells were separated into single-cell suspensions and assayed with 51Cr-labeled herpes simplex 1-infected Chang liver target cells. Significant ADCC activity was detected in 19 of 26 (73%) of freshly assayed fetal spleen cell preparations from fetuses of 17-24 wk gestational age. This activity, however, was significantly less than concurrently run adult peripheral blood mononuclear cells. After plastic adherence the fetal spleen ADCC activity from nonadherent cells was not significantly different from whole spleen preparations. Surprisingly, ADCC activity in nonadherent fetal cells dropped significantly after exposure to latex beads, an effect not seen in nonadherent adult lymphocytes. Thus, either fetal monocyte-derived (macrophages) fetal spleen cells do not efficiently adhere to plastic or a unique nonadherent population of latex-sensitive immunocytes is capable of mediating ADCC activity in the fetus. We suspect the former conclusion to be the more plausible; however, fluorescence-activated cell sorter staining of fetal cells was not sufficient to confirm these suspensions by fluorescence-activated cell sorter analysis.

Prevalence of antibodies to herpes simplex virus in pregnant women in Stockholm in 1969, 1983 and 1989: implications for STD epidemiology

Prevalence of antibody to herpes simplex virus types 1 and 2 was assessed in consecutive serum samples from a total of 3700 women pregnant in 1969, 1983, or 1989 from the same catchment area in Stockholm. There was little change in seroprevalence of antibody to herpes simplex type 1 in the 3 groups, but age-adjusted herpes simplex virus type 2 antibody prevalence was 19, 33, and 33% respectively. Increase in type 2 seropositivity with age was slight and similar in 1969 and 1989, but steep in 1983, indicating a shift in sexual behaviour. However, rising prevalence in women will be mirrored by rising prevalence in their male partners. The increase from 1969 to 1989 will thus partly be due to higher risk of infection per partner, and cannot be taken as direct evidence of increased rate of partner change during this 20-year period.

[The determination of the antigenic activity of recombinant virus-specific polypeptides from the herpes simplex virus types 1 and 2 and their use in immunoenzyme analysis]

The structural and nonstructural recombinant proteins of HSV type 1 and type 2 were expressed in E. coli by fusion with cro-beta-galactosidase proteins. These proteins containing amino acid sequences of ICP4, ICP27, ICP47, ICP22, major capsid protein and major DNA-binding proteins of HSV types 1 and 2 reacted in immunoblotting with the corresponding anti-HSV sera from hyperimmune rabbits. The nonstructural recombinant proteins can be used for enzyme immunoassay detection of HSV1 or HSV2 type-specific antibodies in sera from patients with acute HSV infection.

Application of a transformed cell line constitutively expressing HSV-1 polypeptides for the detection of HSV antibodies in human sera by an enzyme immunoassay

We have previously reported the construction of a cell line BA4, constitutively producing the glycoproteins gD, gG, and alpha 4, the major regulatory protein of HSV-1. These cells have been selected in stepwise increasing concentrations of methotrexate and shown to produce much higher amounts of gD than non-selected cells. Extracts of the selected cells were used in an enzyme linked immunosorbent assay to detect HSV antibodies in human sera obtained from Greek blood donors. We report here that (i) the assay developed is able to distinguish HSV antibody positive from negative human sera and (ii) that its application in an epidemiological survey showed that the incidence of HSV infection in the general population in Greece is 90.4%.

Gastrointestinal invasion by herpes simplex virus type 1 inoculated cutaneously into the immunosuppressed mice

The pathogenesis of infection in mice with herpes simplex virus type 1 (HSV-1) strain 7401H was studied. Mice immunosuppressed by intraperitoneal injection of cyclophosphamide were inoculated cutaneously into the flank with the virus and developed severe zosteriform skin lesions. All of them died within 2 weeks after the infection, while most of the normal mice survived the viral infection with healing of the lesions. In the gastrointestinal tract of the immunosuppressed mice, macroscopic abnormalities were frequently observed, and infectious viruses were detected on days 7 to 9. The viruses were also detectable in the dorsal root ganglia and the spinal cord of thoracolumbar area on days 5 to 7, and in the celiac plexus on day 7. However, no viruses were detected in the blood. Immunohistological examination of the gastrointestinal tract revealed that the viral antigens were localized in Auerbach's myenteric plexus. These results suggest that HSV-1 inoculated into the flank skin invaded the gastrointestinal tract via the nervous system, which gastrointestinal involvement might possibly have caused the death of the mice.

Triple retinal infection with human immunodeficiency virus type 1, cytomegalovirus, and herpes simplex virus type 1. Light and electron microscopy, immunohistochemistry, and in situ hybridization

PURPOSE

This report describes the histopathologic and virologic findings of the retina from a 55-year-old bisexual patient with the acquired immune deficiency syndrome (AIDS), who had concurrent human immunodeficiency virus type 1 (HIV-1), cytomegalovirus (CMV), and herpes simplex virus type 1 (HSV-1) retinitis, and was treated with ganciclovir.

METHODS

The eyes were obtained at autopsy and processed for light microscopy and transmission electron microscopy. Immunohistochemical stains for HSV-1, CMV, HIV-1, varicella zoster virus, and glial fibrillary acidic protein were carried out using the peroxidase-antiperoxidase and streptavidin-biotin-alkaline phosphatase techniques. For in situ hybridization, a radiolabeled CMV DNA probe (Eco-RI-Y fragment of strain AD 169) was used.

RESULTS

Results of histopathologic examination showed a full-thickness necrotizing retinitis with cytomegalic and herpes viral intranuclear inclusions in cells of the neurosensory retina, retinal vascular endothelium, and the retinal pigment epithelium. Some areas of the retina were replaced by glial tissue. The choroid contained only a few chronic inflammatory cells. Immunoperoxidase studies disclosed CMV antigens diffusely distributed throughout all layers of the retina and the retinal pigment epithelium. Herpes simplex virus type 1 antigens were present in retinal cells and the retinal vascular endothelium. Human immunodeficiency virus type 1 antigens were found in mononuclear cells in all layers of the sensory retina. Dual infections with HIV-1 and CMV of individual multinucleated giant cells of glial origin were demonstrated immunohistochemically. Transmission electron microscopy showed herpes viral particles in the vascular endothelium of the retinal vessels and the choriocapillaris. Human immunodeficiency virus particles were identified in the endothelium of the choriocapillaris.

CONCLUSIONS

The possibility of multiple viral infections of the retina, mimicking classic CMV retinitis, should be considered in the clinical and histologic differential diagnosis of necrotizing retinitis in patients with AIDS.

Rapid diagnosis of herpetic keratitis using direct immunoperoxidase technique

The direct immunoperoxidase technique was tested for diagnosis of herpetic keratitis. The technique was performed on corneal epithelial specimens from 28 herpetic keratitis cases and 12 controls. Ulcers were stained with rose bengal or fluorescein and examined at the slit-lamp biomicroscope to differentiate between herpetic and nonherpetic etiology. Scrapings obtained from the corneal epithelial ulcers were stained with direct immunoperoxidase technique. The whole procedure, including staining and examination of the slides, took a total of 70 min. The test proved to be accurate, easy to perform and to interpret, rapid and relatively inexpensive with a sensitivity of 93%, and a specificity of 100%.

Immunization with replication-defective mutants of herpes simplex virus type 1: sites of immune intervention in pathogenesis of challenge virus infection

Replication-defective mutants of herpes simplex virus type 1 (HSV-1) were used as a new means to immunize mice against HSV-1-mediated ocular infection and disease. The effects of the induced immune responses on pathogenesis of acute and latent infection by challenge virus were investigated after corneal inoculation of immunized mice with virulent HSV-1. A single subcutaneous injection of replication-defective mutant virus protected mice against development of encephalitis and keratitis. Replication of the challenge virus at the initial site of infection was lower in mice immunized with attenuated, wild-type parental virus (KOS1.1) or replication-defective mutant virus than in mice immunized with uninfected cell extract or UV-inactivated wild-type virus. Significantly, latent infection in the trigeminal ganglia was reduced in mice given one immunization with replication-defective mutant virus and was completely prevented by two immunizations. Acute replication in the trigeminal ganglia was also prevented in mice immunized twice with wild-type or mutant virus. The level of protection against infection and disease generated by immunization with replication-defective mutant viruses was comparable to that of infectious wild-type virus in all cases. In addition, T-cell proliferative and neutralizing antibody responses following immunization and corneal challenge were of similar strength in mice immunized with replication-defective mutant viruses or with wild-type virus. Thus, protein expression by forms of HSV-1 capable of only partially completing the replication cycle can induce an immune response in mice that efficiently decreases primary replication of virulent challenge virus, interferes with acute and latent infection of the nervous system, and inhibits the development of both keratitis and systemic neurologic disease.

Chimeric parvovirus B19 capsids for the presentation of foreign epitopes

Chimeric proteins consisting of the VP2 capsid protein of human parvovirus B19 and defined linear epitopes from human herpes simplex virus type 1 and mouse hepatitis virus A59 inserted at the N-terminus and at a predicted surface region were expressed by recombinant baculoviruses. The chimeric proteins expressed the inserted epitopes and assembled into empty capsids. Immunoelectron microscopy indicated that the epitopes inserted in the loop were exposed on the surface of the chimeric particles. The chimeric capsids were immunogenic in mice and antibodies specific for the inserted sequences were induced. In the case of MHV, antibodies were produced that recognized the epitope in the context of native virus. Mice immunized with the chimeric capsids were partially protected against a lethal challenge infection with either MHV or HSV.

Interferon-alpha generation in mice responding to challenge with UV-inactivated herpes simplex virus

In humans with advanced human immunodeficiency virus (HIV) infection, an interferon-alpha (IFN-alpha) response by a specialized blood mononuclear cell to herpes simplex virus (HSV) in vitro is associated with resistance to opportunistic infections. A cell type of unknown lineage, designated the natural IFN-producing cell (NIPC), has been identified preliminarily as the source of these IFNs and may have a role in other host defense functions. Earlier studies suggested the existence of analogous HSV-responsive cell populations in mice. The role specifically of IFN-alpha in the murine system, however, has not been characterized. Using IFN bioassay and neutralization with antisera against Type I IFNs and IFN-beta, we have defined the types and sources of IFNs produced by mice in response to in vivo and in vitro challenge with UV-inactivated HSV. After intraperitoneal inoculation with HSV, BALB/c and C57Bl/6 strains produced characteristically different levels of serum IFNs that appeared principally to be IFN-alpha. The response of mononuclear cells from these mice differed from that of the intact mouse. Isolated cells from bone marrow and spleen released detectable IFNs much later than did whole animals, and the IFNs produced by marrow, spleen, and peritoneal cells were usually neutralized by the anti-IFN-beta. Only bone marrow cells produced detectable amounts of IFN-alpha. Both intact mice and their cells became refractory to restimulation with similar kinetics.

Mechanism of virus-induced Ig subclass shifts

Infection of mice with live viruses leads to a dramatic increase in the amount of IgG2a Ig with a consequent shift in the ratio of IgG1/IgG2a. To examine the Ig subclass shift induced by viral infection, we challenged mice with live virus, inactivated virus, or replication-defective mutant viruses that were able to infect cells and produce some viral proteins but were not able to complete a replicative cycle. While killed (or inactivated) virus was capable of inducing HSV-specific antibody, it did not stimulate a shift in the subclass of the total Ig. Replication-defective mutant viruses that fail to express a functional ICP8 or ICP27 protein, but not a mutant expressing a defective ICP4 protein, were able to stimulate the shift. Thus, only a portion of the lytic cycle is sufficient to induce the shift. At least part of the effect is mediated by IFN-gamma.

Recombinant human Fab to glycoprotein D neutralizes infectivity and prevents cell-to-cell transmission of herpes simplex viruses 1 and 2 in vitro

Herpes simplex viruses 1 and 2 (HSV-1 and -2) are associated with a number of conditions of varying severity, which are only partially responsive to current therapies. Human antibodies to the viruses offer a potential alternative. We describe here the generation of panels of human monoclonal Fab fragments to HSV-1 and -2 by panning a phage display combinatorial antibody library against whole lysates from the two viruses. Each lysate selected a largely distinct set of Fabs, although all of the Fabs were cross-reactive with both viruses. In a plaque-reduction assay, one Fab neutralized HSV-1 at 0.25 microgram/ml (50% reduction) and HSV-2 at 0.05 microgram/ml. This Fab also inhibited plaque formation when applied to virus-infected monolayers, completely abolishing HSV-2 plaque development at 25 micrograms/ml 72 hr postinfection, indicating the ability of the Fab to prevent cell-to-cell spread of virus. The Fab was shown to recognize viral glycoprotein D and to neutralize virus primarily by a postattachment mechanism. Recombinant Fabs may be useful for topical administration, although whole antibody will probably be required for systemic use.

Nuclear magnetic resonance investigation of virus-lymphomonocyte interactions

The water protein spin-lattice relaxation time (T1) was measured in suspensions of human peripheral blood mononuclear cells (PBMC), uninfected or infected with type 1 herpes simplex virus, human cytomegalovirus and rubella virus. In the infected samples, T1 enhancements, which linearly depend on virus concentration, were observed. This T1 increase can be related to the early changes induced by the virus adsorption of the cells, not always confirmed by virus-induced cytopathic effect (CPE) in cocultures of infected PBMC and other sensitive cells. Compared with other conventional virological techniques, this NMR method seems to be rapid and sensitive. The NMR response was reproducible and specific, since neutralization of the viral infection by homologous antisera consistently matched the neutralization of the virus-induced NMR effects. These observations suggest that fast and sensitive 1H-NMR relaxation techniques can be implemented in virological diagnosis directly on pathological materials.

Cytomegalovirus/herpesvirus and carotid atherosclerosis: the ARIC Study

Ubiquitous viruses such as members of the human herpes virus group, particularly cytomegalovirus (CMV), have been proposed to be clinically important agents in the initiation and progression of atherosclerosis. Antibodies to CMV and herpes simplex virus type 1 (HSV1) and type 2 (HSV2) were determined in 340 matched case-control pairs from the Atherosclerosis Risk in Communities (ARIC) Study. Cases were defined by B-mode ultrasonography as persons with thickened carotid artery walls consistent with early atherosclerosis but without a history of cardiovascular disease. Controls were defined as persons without thickened walls or history of cardiovascular disease. The case-control odds ratio for CMV antibodies was 1.55 (P = .03), for HSV 1.41 (P = .07), and for HSV2 0.91 (P = .63). When adjustment was made for potential confounders, the odds ratios were 1.36 for CMV (P = .24), 1.21 for HSV1 (P = .45), and 0.61 (P = .05) for HSV2. These results suggest a modest association between CMV and asymptomatic carotid wall thickening consistent with early atherosclerosis.

The role of HSV-induced Fc- and C3b (i)-receptors in bacterial adherence

Herpes simplex virus type-1 (HSV-1) induces Fc- and C3b(i)-receptors on infected cells. The role of these receptors in bacterial superinfection was studied by comparing the adherence of non-opsonised and opsonised bacteria to HSV-infected and non-infected HEp-2 cells. A flow cytometric adherence assay, based on the fluorescent quantitation of FITC-labelled bacteria, was developed. Opsonisation of Staphylococcus epidermidis with human serum, resulted in a marked increase in adherence to HSV-infected cells and revealed a role for C3b(i)R- and FcR-mediated adhesion. However, the enhanced adherence never exceeded the level of attachment to non-infected cells. Increased adherence of other pathogenic bacteria, including Escherichia coli, Streptococcus pneumoniae, Haemophilus influenzae and Pseudomonas aeruginosa was not observed, indicating that the HSV-receptors play a minor role in secondary infections. Bacterial adhesion factors such as the fimbriae of E. coli played a more dominant role in the adherence of bacteria to HSV-infected cells.

Prior infection by respiratory syncytial virus or parainfluenza viruses augments virus-specific IgG responses induced by the measles/mumps/rubella vaccine

We found previously that immunizing cyclophosphamide-treated mice with one Paramyxoviridae virus mixed with dimethyl dioctadecyl ammonium bromide induces T cells which apparently also recognize other Paramyxoviridae viruses. This finding and the fact that respiratory syncytial virus (RSV) and parainfluenza viruses (PIVs) infect children early in life led us to ask if prior RSV or PIV infections influence the antibody response to measles and mumps vaccine viruses. Detection of virus-specific IgG in serum specimens collected randomly or at defined times after measles/mumps/rubella (MMR) vaccination was done with solid-phase enzyme immunoassays. The antibody-binding data obtained were converted to serum antibody titers by an immunoassay curve-fitting computer program. Prior infection by RSV and PIVs correlated with an augmented IgG response not only to measles and mumps virus, but also to rubella virus. Furthermore, the augmentation was greater for responders below the median response. These data show that common early childhood viral infections can influence immunity induced by the MMR vaccine.

Acute retinal necrosis syndrome associated with herpes simplex keratitis

BACKGROUND

Although acute retinal necrosis (ARN) syndrome is caused by a herpes group virus, association of herpetic keratitis with ARN syndrome is uncommon. A case of unilateral ARN syndrome with herpes simplex keratitis is discussed.

METHODS

A 40-year-old man developed unilateral keratitis, necrotic retinitis, retinal vasculitis, vitritis, and iritis consistent with ARN syndrome 1 month after treatment for ipsilateral facial nerve palsy and auricular herpetic vesicles (Tolosa-Hunt syndrome). Impression cytologic examination of the corneal epithelial ulcer that developed concurrent with the intraocular findings and of the aqueous humor (obtained by paracentesis) was performed.

RESULTS

Cells that reacted with anti-herpes simplex virus type 1 (HSV-1) antibody were detected on impression cytology, and DNA fragments corresponding to the HSV-1 DNA sequence were detected in the aqueous humor.

CONCLUSION

This case shows that ARN syndrome may, on rare occasions, be associated with herpes keratitis secondary to HSV-1.

Time course of cytotoxic T lymphocyte activity after inoculation of herpes simplex virus into the anterior chamber of mice

The time course of the activity of cytotoxic T lymphocytes (CTL) was studied after injecting herpes simplex virus (HSV) into the anterior chamber of C3H/He mice and compared with that following corneal inoculation. CTL activity in cervical lymph nodes was suppressed during the 14 days after the inoculation, while that in the spleen increased 2 days earlier compared with the activity after corneal inoculation. The difference between the peaks of CTL activity after inoculation via each route was not significant. Thus, CTLs from the spleen appear to play a role in the immune response defending mice against intraocular infection by HSV.

Stromal keratitis induced by a unique clinical isolate of herpes simplex virus type 1

Glycoprotein C (gC)-negative clinical isolates of herpes simplex virus type 1 (HSV-1) are very rare. An HSV-1 strain (TN-1), isolated from a patient with herpetic keratitis, exhibited a gC-negative phenotype. While a gC-negative mutant showed reduced pathogenicity and failed to induce herpetic stromal keratitis (HSK) in a previously reported mouse model, TN-1 induced HSK in mice comparable to RTN-1-20-3, a gC-positive recombinant virus derived from TN-1. Virus growth in eyes and brains and the mortality of TN-1-inoculated mice were equal to or higher than those of RTN-1-20-3-inoculated mice.

Necrotizing retinitis in severe combined immunodeficiency mice following intracameral inoculation of herpes simplex virus type 1

Necrotizing retinitis in severe combined immunodeficiency (SCID) mice following intracameral inoculation of herpes simplex virus type 1 provided an experimental model for acute retinal necrosis in AIDS and other immunocompromised patients. In order to assess the involvement of the immunological response in the pathogenesis, adoptive transfer experiments were conducted. Without transfer, SCID mice developed predominantly unilateral necrotizing retinitis and died within 10 days. Transfer of immune serum lengthened the survival time but resulted in bilateral necrotizing retinitis. Two of 5 mice transferred with CD4+ T cells and none of 7 transferred with CD8+ T cells developed bilateral necrotizing retinitis. Our results indicate that ipsilateral retinal necrosis occurs with or without a specific immunological response, and that antibodies and/or CD4+ T cells accelerate the contralateral retinal necrosis.

The significance of herpes viral latency in the spiral ganglia

To better understand the pathogenesis of idiopathic sudden hearing loss (ISHL), the possibility of latent virus infection in the spiral ganglion cell was considered. Only few spiral ganglion cells showed positive viral antigen after systemic guinea pig-specific cytomegalovirus (GPCMV) inoculation indicating the absence of hearing loss but the possibility of a subsequent latent infection. By using a modern molecular biological technique we have detected the herpes simplex virus type-1 (HSV-1) DNA in human spiral ganglia. The concept of establishing viral latency in the spiral ganglion cells with periods of reactivation fits with the clinical picture seen in ISHL, even though the mechanism of reactivation still remains unclear.

CO2 anesthesia facilitates a serum antibody response to orally-administered antigens

Under most experimental circumstances, mice fed a protein antigen produce a smaller serum antibody response than the response elicited in mice that are parenterally immunized with that same antigen. In our experiments, mice fed keyhole limpet hemocyanin or herpes simplex virus type 1 had low, if any, serum IgG antibody responses regardless of whether antigen consumption was voluntary (in drinking fluids) or involuntary (force-fed by pipette). However, when force-feeding occurred during CO2 anesthesia, mice produced significantly higher serum antibody responses, which were comparable to those elicited in mice injected intraperitoneally with the same antigen. Although its mechanism of action is unclear, this potentiating effect does not appear to be mediated by possible CO2-mediated entry of the antigens into the respiratory tract, since mice fed antigen immediately before CO2 anesthesia also had a substantial antibody response.

In vivo priming and activation of memory cytotoxic T-lymphocytes (CTL) by a chimeric simian virus 40 T antigen expressing an eight amino acid residue herpes simplex virus gB CTL epitope

The simian virus 40 (SV40) large T antigen was used as an immunogenic vector to express a herpes simplex virus type 1 (HSV-1) glycoprotein B (gB), H-2Kb-restricted cytotoxic T lymphocyte (CTL) recognition epitope corresponding to amino acid residues 498-505. Immunization of naive, C57BL/6 mice with a cell line, B6/350gB, expressing the chimeric T antigen was able to induce the generation of gB498-505-specific CTL in both the lymph nodes and the spleen. Splenic-derived, gB498-505-specific memory CTL (CTLm) were detected in these mice for at least 6 months following immunization at a slightly lower frequency than in those mice immunized with infectious HSV-1. B6/350gB was also able to activate in vitro gB498-505-specific memory CTL obtained from mice previously challenged with HSV. Overall, these findings support the use of a chimeric T antigen as a vector in determining the immunogenic potential of individual CTL epitopes and to assess their potential contribution in inducing a protective immune response in vivo.