Selective impairment of lymphocyte reactivity to varicella-zoster virus antigen among untreated patients with lymphoma.

Herpes zoster is a frequent complication of lymphoreticular malignancy. In this study two assays of in vitro cellular immune response to varicella-zoster virus (VZV) antigen, lymphocyte transformation and interferon production, were performed in normal subjects with recent and remote VZV infection. The responses of patients with lymphoma were measured before treatment and during long-term remission and then compared with those of normal subjects. Despite levels of antibody to VZV that were equivalent to those in normal subjects, 44% of the untreated lymphoma patients showed a lower transformation response to VZV antigen than the normal patients. Production of interferon in response to VZV antigen was absent in 32% of the untreated patients. In contrast, lymphocyte responses in untreated patients to herpes simplex virus antigen were within the range observed in a normal population. Interferon production by lymphocytes in response to cytomegalovirus antigen was also lower among untreated lymphoma patients than among normal patients, but lymphocyte transformation was not. Twenty-two percent of lymphoma patients in long-term remission continued to have diminished cellular immune responses to VZV antigen. Observations in these patient populations and in normal subjects with acute herpes zoster suggest that deficiencies in in vitro lymphocyte responses may correlate with increased susceptibility to clinical infection with VZV.     

Specific cell-mediated immunity and the natural history of congenital infection with cytomegalovirus

Viral excretion, antibody response, and specific cell-mediated immunity were studied in 104 children with congenital cytomegalovirus (CMV) infection followed from birth. The study population demonstrated prolonged viral shedding and stable, moderate levels of serum antibody. The majority of patients ceased salivary shedding of CMV by two years of age but continued to have viruria through the fifth year. Patients who had symptomatic infection or CNS sequelae were similar to asymptomatic patients with regard to both viral excretion and antibody response. Although symptomatic patients had significantly weaker specific blastogenic responses from one to seven years of age, the majority of patients from both groups had no detectable response to CMV through their fifth year. The impairment was highly specific for CMV, as patients with congenital CMV infection who had antibody to herpes simplex virus did have a lymphocyte blastogenic response to the latter virus. Although specific lymphocyte blastogenesis did not correlate with outcome, the presence of a positive response was associated with cessation of viruria.     

Role of T lymphocytes in cellular immune responses during herpes simplex virus infection in humans.

Lymphocyte blast transformation and interferon production in mononuclear cell culture prepared on Ficoll-Hypaque gradients from individuals with herpes simplex virus-I infection were enhanced by a disease recurrence. Responses to both herpes simplex virus-2 and phytohemagglutinin were unaltered. Transformation to herpes simplex virus-I antigen was adversely affected by depleting either thymus-derived (T) lymphocytes or bone marrow-derived (B) lymphocytes together with monocytes from cultures. The transformation response was reconstructed when the selectively depleted lymphocyte populations were recombined. X-irradiation of either T or B lymphocytes and monocytes showed that T lymphocytes incorporated [3H]thymidine with the aid of a radioresistant non-rosetting cell, probably a monocyte. Depletion of B lymphocytes and monocytes, but not of T lymphocytes, resulted in reduction in interferon production. Irradiated B lymphocytes and monocytes failed to produce significant quantities of interferon, suggesting that a radiosensitive B cell was a major interferon source.     

Infection with herpes simplex virus and cell-mediated immunity after marrow transplant

The relationship between herpes simplex virus (HSV) infection and specific cell-mediated immunity was investigated in 141 patients before and for the first four months after marrow transplant. Sixty-two (82%) of 76 seropositive patients but only one of 65 seronegative patients developed HSV infection. Lymphocyte responses to HSV antigen were suppressed immediately after transplant and subsequently became reactive in those patients with HSV infection. The presence or absence of antibody to HSV in the donor before transplant did not influence the response. Seventy long-term survivors of marrow transplant were also studied. Among 60 patients who had pretransplant serum available for study, 26 (68%) of 38 who had been seropositive before transplant had positive responses compared with none of 22 who had been seronegative. Recovery of responsiveness to HSV antigen after marrow transplant is primarily related to recurrent virus infection and not to the pretransplant immune status of the donor.     

Impaired lymphocyte transformation response to cytomegalovirus and phytohemagglutinin in recipients of renal transplants: association with antithymocyte globulin

Cell-mediated immunity was assessed in 38 seropositive recipients of renal transplants by measuring the in vitro lymphocyte transformation response (LTR) to cytomegalovirus (CMV) and to phytohemagglutinin; results were correlated with clinical course, viral excretion, and immunosuppressive treatment. Thirteen seropositive controls all responded to CMV with a mean stimulation index of 31 +/- 6; 14 seronegative controls all had stimulation indices of less than 3. LTR to CMV was found to require both thymus-derived lymphocytes and macrophages. Before immunosuppression, responses of patients were similar to those of controls. After renal transplantation mean LTRs to CMV were dramatically reduced up to 18 months postoperatively, especially in patients treated with antithymocyte globulin. Viremia and CMV-related illness were significantly more frequent in recipients of antithymocyte globulin. Although there was only a rough correlation between clinical events and LTR to CMV, five deaths were noted among seven patients (all treated with antithymocyte globulin) who failed to respond to phytohemagglutinin on two consecutive tests.     

Cell-mediated immunity of cytomegalovirus infection in normal subjects and cardiac transplant patients.

Two assays of cell-mediated immunity, lymphocyte transformation and interferon production, were adapted to test for specific immunity to cytomegalovirus (CMV). Normal individuals seropositive for CMV had a mean transformation index of 7.9 in response to antigen of the Davis strain of CMV, whereas all of 14 seronegative normal individuals had transformation indexes of less than or equal to 3.0. Interferon production in seropositive and seronegative individuals was not statistically different. One to two months after CMV mononucleosis (after the termination of viruria), normal individuals had increased transformation indexes. Recipients of cardiac transplants within six months after transplant had normal levels of antibody to CMV; lymphocyte transformation and interferon production in these subjects were markedly decreased and returned to normal by three years and between one and three years after transplant, respectively. A syndrome of unexplained fever, hepatitis, pneumonitis, leukopenia, and atypical lymphocytes was common in a group of recipients with primary CMV infection. Shedding of virus was frequent in these symptomatic patients and in patients with repeat infection during the first three years after transplant. These assays appear to identify periods of immune deficits correlating with increased incidence of infection with CMV.     

Primary herpes simplex virus type-2 infection as a cause of liver failure after liver transplantation

We report a case of fatal primary herpes simplex virus type-2 (HSV-2) infection following liver transplantation, which manifested with fever and liver failure in the absence of muco-cutaneous disease. The infection was characterized by high levels of HSV DNA in blood and the patient's inability to mount HSV-specific T-cell responses while showing preserved T-cell responses against cytomegalovirus. The donor was HSV-1 immunoglobulin G (IgG) seronegative and HSV-2 IgG seropositive, whereas the recipient was HSV-1 and HSV-2 IgG seronegative, suggesting that the graft may have been the source of the infection. In HSV-seronegative recipients of grafts from HSV-seropositive donors, HSV infection should be included in the differential diagnosis of a febrile illness, regardless of the absence of muco-cutaneous disease. In this setting, real-time polymerase chain reaction applied to blood samples provides a sensitive, rapid, and quantitative diagnostic tool.     

Interferon Production,Cellular and Humoral Immunity in Splenectomized Patients

Undetectable levels of circulating interferon were found in 35 splenectomized patients and in 14 controls. In addition, no differences in virus, purified protein derivative (PPD), and phytohaemagglutinin (PHA) induced interferon production were observed between the patients and the controls. Virus induced lymphocyte transformation tended to be reduced after splenectomy, but only the herpes simplex virus (HSV) induced transformation index was significantly reduced in splenectomized patients without residual splenic tissue (P < 0.05). In contrast, the PHA lymphocyte transformation was unchanged in patients and controls. The number of natural viral antibodies in splenectomized patients did not differ from that of controls. Furthermore, there were no major differences in the magnitude of the titers of the sero-positive cases between the various groups. Thus, splenectomy does not interfere with interferon production in vitro, and as seen from natural viral antibodies, no impairment of humoral immunity was observed. The reduced HSV lymphocyte transformation may indicate an impaired lymphocyte function after splenectomy.     

Specific cell-mediated immunity in children with congenital and neonatal cytomegalovirus infection and their mothers.

Cell-mediated immunity (CMI) to cytomegalovirus (CMV) and herpes simplex virus type 1 (HSV-1) was examined in 35 mothers and 30 of their offspring with congenital or neonatal CMV infection by means of the lymphocyte transformation assay. Eleven offspring did not respond to CMV antigen, and 15 of the 19 positive children displayed lower responses than those of normal immune adults. Productive infection in the younger children at the time of assay and the presence of disease correlated strongly with the absence of responses. The mothers as a group also demonstrated impaired CMI to CMV while reacting normally to HSV-1 antigen. Neither time after transmission of infection nor viral excretion was significantly associated with impaired CMI, although a trend toward diminished responses was evident among women who were shedding virus. Mitogen stimulation was normal in all test subjects. These findings imply that deficient specific CMI may play a role in the genesis of persistent CMV infection and fetal pathology.     

Herpes simplex virus resistant to acyclovir. A study in a tertiary care center

STUDY OBJECTIVE: To determine the sensitivity of herpes simplex virus isolates to acyclovir and the importance of resistant isolates in hospitalized patients. DESIGN: Retrospective incidence cohort study. SETTING: All herpes simplex virus isolates cultured over 1 year from patients followed at a tertiary care center. PATIENTS: Consecutive herpes simplex virus isolates were collected from 207 patients, including immunocompetent patients, patients with malignancy, neonates, bone marrow and organ transplant recipients, and patients seropositive for human immunodeficiency virus. MEASUREMENTS AND MAIN RESULTS: A rapid nucleic acid hybridization method was used to assess susceptibility to acyclovir. Acyclovir-resistant herpes simplex viruses were recovered from 7 of 148 immunocompromised patients (4.7%) but from none of 59 immunocompetent hosts. Clinical disease was found in all 7 patients with resistant herpes simplex virus and was more severe in pediatric patients. All resistant isolates were from acyclovir-treated patients and had absent or altered thymidine kinase activity by plaque autoradiography. CONCLUSION: Herpes simplex virus resistant to acyclovir arises relatively frequently in immunocompromised patients and may cause serious disease. Rapid detection of resistance permits antiviral therapy to be individualized. Antiviral susceptibility testing to monitor viral resistance should be encouraged, especially in tertiary care settings.     

Recombinant HIV structural proteins detect specific cellular immunity in vitro in infected individuals

Peripheral blood mononuclear cell (PBMC) cultures were established from patients with antibody to human immunodeficiency virus (HIV). Asymptomatically infected patients [5 of 19] had significant lymphocyte transformation responses induced in culture by a purified, recombinant envelope glycoprotein (rgp120) from the virus. A few (4 of 55) subjects with AIDS related complex (ARC) and no subjects with AIDS (0 of 29) had proliferative responses to this protein. These responses correlated directly with circulating levels of helper/inducer lymphocytes (p less than .01) and indirectly with virus antigen in blood (p = .04). Also, these responses occurred significantly less frequently than responses to herpes simplex virus (HSV) or cytomegalovirus (CMV) antigens in seropositive ARC patients (p less than .005). These data indicate that the frequency of immune cellular responses to rgp120 decline in association with disease progression, and become undetectable in frank AIDS. As rgp120-induced proliferation was not observed in cells from 15 seronegative immunocompetent subjects, this response appears immune specific. Immune T-lymphocyte-mediated responses to this HIV envelope glycoprotein may allow the prediction of future clinical events and may be useful in monitoring immune-enhancing therapy in patients with ARC and AIDS.     

Comparative virulence and immunogenicity of the Towne strain and a nonattenuated strain of cytomegalovirus

The Towne strain cytomegalovirus and a low-passage strain, Toledo-1, were compared for virulence and immunogenicity in healthy adult male subjects to determine the suitability of the Towne strain for vaccination. Five seropositive subjects who received the Toledo-1 strain developed infections ranging in severity from laboratory abnormalities to mild mononucleosis syndromes (mean incubation, 4.7 weeks). None of the four seronegative subjects receiving the Towne strain developed systemic infection, but all developed delayed local reactions at the injection sites. All subjects developed cytotoxic lymphocyte responses specific to cytomegalovirus, usually HLA-restricted, but these were of greater magnitude and duration in the Toledo-1 recipients. The latter also developed natural killer cell and interferon responses, atypical lymphocytosis, inversion of helper/suppressor cell ratios, and depressed responses to T-cell mitogens, none of which occurred in Towne strain recipients. The results further substantiate the avirulence and immunogenicity of the Towne strain cytomegalovirus.     

Identification of patients with increased risk of infection with herpes simplex virus after renal transplantation.

Forty-nine recipients of renal allografts were studied for infection with herpes simplex virus (HSV) before and at sequential intervals after transplantation. Forty-four (90%) of the patients studied were initially seropositive for neutralizing antibody to HSV type 1. HSV was not shed prior to transplantation nor by any of the five seronegative recipients after transplantation. Twenty-nine (66%) of the 44 seropositive patients shed virus postoperatively: 23 in saliva, three in urine, and three in both sites. Twenty (63%) of 32 seropositive patients examined developed herpetic mucocutaneous lesions. Both viral shedding and lesions were most prevalent during the first four weeks after transplantation. Twenty-nine (85%) of 34 patients with antibody titers of 1:256-1:4,096 and zero of 10 with titers of 1:8-1:128 shed HSV postoperatively (P less than 0.0001). The group with high antibody titers before transplantation were also more likely to develop lesions after transplantation (P = 0.002) as were those with a positive history (P = 0.017). The ability to predict symptomatic HSV recurrences in renal transplant patients could be a valuable aid in identifying individuals with which to evaluate antiviral compounds.     

BK and JC virus infections in recipients of bone marrow transplants

Fifty-five recipients of bone marrow transplants were monitored prospectively for urinary excretion of BK (BKV) and JC (JCV) viruses and for infections with other viruses. For both BKV and JCV, viruria occurred exclusively in patients who were seropositive at transplantation, a finding indicating that shedding of virus was very likely the result of reactivation. BKV reactivation, which occurred in 26 (55%) of 47 BKV-seropositive patients, was far more common than JCV reactivation, which was detected in only two (7%) of 30 JCV-seropositive patients (P less than .0001). In most patients, BK viruria began two to eight weeks after transplantation and resolved spontaneously after a two- to three-week period. Posttransplantation, there was a temporal pattern in the onsets of infection with the different viruses; herpes simplex virus infections occurred first (mean, 7 d), followed by BKV infections (mean, 33 d) and then cytomegalovirus infections (mean, 51 d). BK viruria was associated with hemorrhagic cystitis.     

Latent herpesviruses of humans

The herpesviruses that infect humans characteristically establish a latent infection that may be reactivated later. The consequences of reactivation range from asymptomatic shedding to severe disseminated infection. Varicella-zoster and herpes simplex viruses are both highly neurotropic, establishing nonreplicating infections in sensory ganglia. Latent herpes simplex virus is known to reside in neurons, and the virus-cell interactions involved have been defined to an extent. Cytomegalovirus and Epstein-Barr virus interact with peripheral blood leukocytes. Latent cytomegalovirus infection of human leukocytes has not been proved, although studies in a murine model have implicated B lymphocytes as a repository of latent virus. Epstein-Barr virus is known to persist in a non-replicating state as extrachromosomal DNA in B lymphocytes and to cause "immortalization" of the infected cell; persistence of the viral genome in epithelial cells may also result in malignant transformation, such as nasopharyngeal carcinoma.     

Therapeutic options for herpes simplex infections

Herpes simplex viruses are responsible for a number of disease states in infected individuals. Capable of establishing latent infection, herpes simplex can reactivate, causing pain, discomfort, and psychosocial consequences. Because no cure is available, treatment modalities for herpes simplex infection are required, from both personal and public health standpoints. To date, therapy has centered around the use of antiviral drugs to control infection and suppress recurrences. To expand the scope of available treatments, efforts have focused on the development of vaccines against herpes simplex virus and new agents such as immune response modifiers. Recent data suggest that these new agents are promising in their therapeutic potential.     

Hepatitis C virus-specific T-cell immune responses in seronegative injection drug users

Summary.  T-cell responses to hepatits C virus (HCV) antigens have been reported in high-risk HCV seronegative persons, suggesting that an effective cellular immune response might be able to clear infection without the development of antibodies. Such findings, however, could be explained by waning antibody or cross-reactivity to other antigens. To address these issues, we evaluated HCV-specific T-cell responses in 26 young (age 18–33 years) aviremic, seronegative injection drug users (IDUs) (median duration of injection, 6 years) by interferon-γ enzyme-linked immunospot (ELISpot) assay using 429 overlapping HCV peptides pooled in 21 mixes. Seventeen aviremic, seropositive IDUs (spontaneous resolvers) and 15 healthy people were used as positive and negative controls, respectively. The percentage of patients with HCV-specific cellular immune responses was similar in seronegative and seropositive aviremic IDUs (46% vs 59%, P  = 0.4), while these responses were not detected in any of the negative controls. Among the seronegative IDUs, six (23%) had intermediate to very strong responses to 10–20 peptide mixes and another six (23%) had moderately strong responses for two to six mixes. The 12 seronegative IDUs with HCV-specific T-cell responses had higher demographical and behavioural risk profiles than the 14 IDUs without T-cell responses (estimated risk of HCV infection, 0.47 vs 0.26, P  < 0.01). In conclusion, HCV-specific T-cell responses are common among high-risk, seronegative IDUs. The responses are broad and are associated with risk factors for HCV exposure, suggesting that they reflect true exposure to HCV in seronegative persons.     

Foscarnet therapy for acyclovir-resistant mucocutaneous herpes simplex virus infection in 26 AIDS patients: preliminary data

Mucocutaneous herpes simplex virus (HSV) infections that are resistant to therapy with acyclovir have been recognized with increasing frequency in patients with the acquired immunodeficiency syndrome, although alternative therapies in this setting have not been widely studied. Twenty-six consecutive patients are reported with human immunodeficiency virus infection, who received foscarnet therapy for acyclovir-resistant HSV. Clinical response was noted in 81% of patients; complete reepithelialization of HSV lesions occurred in 73%. Cessation of viral shedding was documented in all of the 11 patients who were recultured. Although adverse effects were frequent, in only 3 patients (12%) did toxicity necessitate discontinuation of therapy. Before foscarnet therapy, 14 patients received vidarabine for acyclovir-resistant HSV. The infection did not resolve in any of the vidarabine-treated patients, and therapy was discontinued in 4 (29%) due to toxicity.     

Immunization against genital herpes with a vaccine virus that has defects in productive and latent infection

An effective vaccine for genital herpes has been difficult to achieve because of the limited efficacy of subunit vaccines and the safety concerns about live viruses. As an alternative approach, mutant herpes simplex virus strains that are replication-defective can induce protective immunity. To increase the level of safety and to prove that replication was not needed for immunization, we constructed a mutant herpes simplex virus 2 strain containing two deletion mutations, each of which eliminated viral replication. The double-mutant virus induces protective immunity that can reduce acute viral shedding and latent infection in a mouse genital model, but importantly, the double-mutant virus shows a phenotypic defect in latent infection. This herpes vaccine strain, which is immunogenic but has defects in both productive and latent infection, provides a paradigm for the design of vaccines and vaccine vectors for other sexually transmitted diseases, such as AIDS.     

Mesenchymal stem cells are susceptible to human herpesviruses, but viral DNA cannot be detected in the healthy seropositive individual

Allogeneic stem cell transplantation is often complicated by reactivation of herpesviruses. Mesenchymal stem cells (MSC) are immunomodulatory and may be used to treat graft-versus-host disease. We investigated if herpesviruses infect and can be transmitted by MSC, and if MSC suppress immune responses to various infectious agents. Mesenchymal stem cells from healthy seropositive donors were evaluated with polymerase chain reaction for the most common herpesviruses: cytomegalovirus (CMV), herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2, Epstein-Barr virus (EBV) and varicella zoster virus. The cytopathological effect (CPE) was investigated and viral antigens analyzed by immunofluorescence after in vitro exposure to CMV, HSV-1 and EBV. We also studied MSC effect on lymphocyte stimulation induced by various infectious agents. No viral DNA could be detected in MSC isolated from healthy seropositive individuals. However, a CPE was noted and intracellular viral antigens detected after infection in vitro by CMV and HSV-1, but not by EBV. The CMV and HSV-1 infections were productive. Lymphocyte proliferation by herpesviruses, candida mannan and protein A from Staphylococcus aureus was suppressed by MSC. The data indicate that the risk of herpesvirus transmission by transplantation of MSC from healthy seropositive donors is low. However, MSC may be susceptible to infection if infused in a patient with CMV or HSV-1 viremia. MSC transplantation may compromise the host's defense against infectious agents.