Viral infections in renal transplant recipients

The Contribution of Human Herpes Viruses to γδ T Cell Mobilisation in Co-Infections

γδ T cells are activated in viral, bacterial and parasitic infections. Among viruses that promote γδ T cell mobilisation in humans, herpes viruses (HHVs) occupy a particular place since they infect the majority of the human population and persist indefinitely in the organism in a latent state. Thus, other infections should, in most instances, be considered co-infections, and the reactivation of HHV is a serious confounding factor in attributing γδ T cell alterations to a particular pathogen in human diseases. We review here the literature data on γδ T cell mobilisation in HHV infections and co-infections, and discuss the possible contribution of HHVs to γδ alterations observed in various infectious settings. As multiple infections seemingly mobilise overlapping γδ subsets, we also address the concept of possible cross-protection.

Clinical Manifestation, Laboratory Findings, and the Response of Treatment in Kidney Transplant Recipients With CMV Infection

OBJECTIVES

To report clinical manifestations, laboratory findings, and treatment outcomes of in kidney transplant recipients who had cytomegalovirus (CMV) infections.

METHODS

This retrospective study evaluated the records of kidney transplant recipients followed regularly from 2001 to 2006. In some patients information was also gathered through a telephone call or physical examination. The CMV infection diagnosis was also made by detecting PP.65 antigen per 50,000 peripheral blood leukocytes.

RESULTS

Of the 200 kidney transplant recipients, 66 were infected with CMV including 42 men and 24 women. The mean patient age was 40 +/- 13 years (range, 14 to 67 years). Seventy-nine percent of the infected patients were diagnosed during the first 6-months after transplantation. All except 22 patients (33%) had constitutional complaints. Fever was present in 65% of patients, abdominal pain in 21%, diarrhea in 20%, and vomiting in 15%. Likewise, pulmonary complaints including cough and dyspnea were reported by 32% and 23%, respectively. However, 20% of patients were completely asymptomatic. Hematologic laboratory data showed anemia (64%), thrombocytopenia (47%), and leukopenia (21%). Seventy eight percent of patients had a serum creatinine <or=2 mg/dL before infection, but it was <or=2 in just 26% at the time CMV was diagnosed and 60% after treatment. Antiviral therapy included intravenous gancyclovir in 80% of patients and gancyclovir plus oral acyclovir in 20%. Corticosteroid pulse therapy was also administered in 78% of patients. No statistically significant correlation was observed between CMV antigen load and the severity of clinical manifestations or the time of response to treatment or the recurrence prognosis. In our series, 1 patient died, 28 treated patients (42%) experienced CMV recurrence, and 37 (56%) showed no recurrence.

CONCLUSIONS

CMV infection should be considered in any renal transplant recipient who has a rise in creatinine even if symptom-free. Despite the results of other studies, we found no prognostic value for the viral antigen load.

Oral and dental aspects of chronic renal failure

The present article reviews, in detail, the current knowledge of the oral and dental aspects of chronic renal failure (CRF). Worldwide, increasing numbers of persons have CRF; thus, oral health care staffs are increasingly likely to provide care for patients with such disease. Chronic renal failure can give rise to a wide spectrum of oral manifestations, affecting the hard or soft tissues of the mouth. The majority of affected individuals have disease that does not complicate oral health care; nevertheless, the dental management of such individuals does require that the clinician understand the multiple systems that can be affected. The clinician should also consider the adverse side-effects of drug therapy and appropriate prescribing, in view of compromised renal clearance.

Treatment of mucocutaneous presentations of herpes simplex virus infections

Infections by herpes simplex virus (HSV) types I and II are diverse and quite frequent. After primary infection, the virus establishes a life-long latency in the sensory ganglia and recrudescences may occur at an unpredictable rate. Recurrent labial and genital herpes infections represent the majority of clinical manifestations of HSV infections. Their management is currently well established using evidence-based medicine data. Primary labial herpes is generally not treated with antivirals in otherwise healthy children, although intravenous aciclovir may be offered in severe primary infections, particularly in the immunocompromised patient. The decision whether or not to treat recurrent labial herpes should be evaluated individually and depends on the frequency and severity of relapses, the impairment of the quality of life, and the cost of therapy. Patients with mild disease may benefit from topical therapy, and those with severe and frequent recurrences may be considered for intermittent or long-term oral antiviral therapy. Primary genital herpes is treated with oral or intravenous antivirals, depending on the severity of the infection and associated symptoms. Recurrent genital herpes can be managed with episodic short courses of oral antivirals in patients whose recurrences are moderate to severe and rare, and have a clear prodrome. Patients with >5 episodes/year, severe recurrences or unrecognisable prodromes may be best managed with long-term suppressive antiviral prophylaxis. HSV is also responsible for a variety of other clinical manifestations, including herpetic whitlow, neonatal infection, disseminated and atypical cutaneous infections, traumatic herpes, eczema herpeticum, and HSV-associated erythema multiforme. HSV infection may also represent a complication following cosmetic procedures of the oro-facial region, surgical and dental interventions, sun exposure and burns. Precise treatment guidelines for these HSV infections are not firmly established.

High incidence of Epstein-Barr virus, cytomegalovirus and human herpesvirus 6 infections in children with cancer

BACKGROUND

A prospective single-center study was performed to study infection with lymphotropic herpesviruses (LH) Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpesvirus 6 (HHV-6) in children with cancer.

METHODS

The group of 186 children was examined for the presence of LH before, during and 2 months after the end of anticancer treatment. Serology of EBV and CMV was monitored in all children, serology of HHV-6 and DNA analysis of all three LH was monitored in 70 children.

RESULTS

At the time of cancer diagnosis (pre-treatment), there was no difference between cancer patients and age-matched healthy controls in overall IgG seropositivity for EBV (68.8% vs. 72.0%; p = 0.47) and CMV (37.6% vs. 41.7%; p = 0.36). During anticancer therapy, primary or reactivated EBV and CMV infection was present in 65 (34.9%) and 66 (35.4%) of 186 patients, respectively, leading to increased overall post-treatment IgG seropositivity that was significantly different from controls for EBV (86.6% vs. 72.0%; p = 0.0004) and CMV (67.7% vs. 41.7%; p < 0.0001). Overall pre-treatment IgG seropositivity for HHV-6 was significantly lower in patients than in controls (80.6% vs. 91.3%; p = 0.0231) which may be in agreement with Greaves hypothesis of protective effect of common infections in infancy to cancer development. Primary or reactivated HHV-6 infection was present in 23 (32.9%) of 70 patients during anticancer therapy leading to post-treatment IgG seropositivity that was not significantly different from controls (94.3% vs. 91.3%; p = 0.58). The LH infection occurred independently from leukodepleted blood transfusions given. Combination of serology and DNA analysis in detection of symptomatic EBV or CMV infection was superior to serology alone.

CONCLUSION

EBV, CMV and HHV-6 infections are frequently present during therapy of pediatric malignancy.

A case of fever of unknown origin with severe stomatitis in renal transplant recipient resulting in graft loss

We present a case of fever of unknown origin and life-threatening stomatitis developed about 60 months after renal transplantation. He was 15 yr old at the transplantation. Bacterial, fungal, and viral infections were not evident. Fever and stomatitis were resistant to acyclovir and to any anti-bacterial or anti-fungal treatment. Graft biopsy revealed a small focus of acute vascular rejection, but the findings were not severe enough to be an etiology of the fever in this case. The administration of cyclosporine (CYA) was stopped 19 d before graftectomy, but the clinical picture was unchanged. Fever and stomatitis was resolved immediately after graftectomy and the discontinuation of immunosuppressants such as mizoribine (MZ) and prednisolone. Pathological changes of the graft included chronic transplant glomerulopathy, acute glomerulitis, and lymphocyte infiltration in peritubular capillaries. Thus we suppose that immunosuppressants were the cause of both fever and stomatitis in this case. We speculate that a fever in this case might be due to the immunosuppressant itself, i.e., CYA or MZ, or viral infection probably herpes-simplex virus infection. It is probably the immunosuppressive state per se that may cause the resistance of his muco-cutaneous lesion to anti-viral agent.

Hodgkin's disease and the Epstein-Barr virus

Hodgkin's disease is an unusual cancer because the malignant cells constitute only a minority of the total tumour mass and, as a consequence, the study of these cells has been a major challenge. Recently, the application of newer technologies, such as single cell polymerase chain reaction (PCR) and gene expression array analysis, to the study of Hodgkin's disease have yielded new insights into the pathogenesis of this tumour. In addition, the recognition that a proportion of Hodgkin's disease tumours harbour the Epstein-Barr virus (EBV) and that its genome is monoclonal in these tumours suggests that the virus contributes to the development of Hodgkin's disease in some cases. This review summarises current knowledge of the pathogenesis of Hodgkin's disease with particular emphasis on the association with EBV.

New strategies for prevention and therapy of cytomegalovirus infection and disease in solid-organ transplant recipients

In the past three decades since the inception of human organ transplantation, cytomegalovirus (CMV) has gained increasing clinical import because it is a common pathogen in the immunocompromised transplant recipient. Patients may suffer from severe manifestations of this infection along with the threat of potential fatality. Additionally, the dynamic evolution of immunosuppressive and antiviral agents has brought forth changes in the natural history of CMV infection and disease. Transplant physicians now face the daunting task of recognizing and managing the changing spectrum of CMV infection and its consequences in the organ recipient. For the microbiology laboratory, the emphasis has been geared toward the development of more sophisticated detection assays, including methods to detect emerging antiviral resistance. The discovery of novel antiviral chemotherapy is an important theme of clinical research. Investigations have also focused on preventative measures for CMV disease in the solid-organ transplant population. In all, while much has been achieved in the overall management of CMV infection, the current understanding of CMV pathogenesis and therapy still leaves much to be learned before success can be claimed.

Oral lesions in organ transplant patients

Patients who have undergone organ transplantation can present with a variety of oral lesions that appear to be related either directly to their medication or arise as a consequence of drug-induced immunosuppression. Such lesions include hairy leukoplakia, an increased propensity to both fungal and viral infections and a high incidence of malignant change, especially lip cancer. Cyclosporin remains the immunosuppressant of choice in most transplant patients. Gingival overgrowth is the main unwanted oral effect associated with cyclosporin. Some 30% of dentate transplant experience this problem, which is further compounded by concomitant medication with a calcium channel blocker. This review appraises the various oral problems that can arise in this group of patients and emphasises the importance of regular oral screening and the establishment of links with the various transplant teams.

Human herpesvirus 6 and human herpesvirus 7 infections in renal transplant recipients and healthy adults in Turkey

We explored the prevalence of human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) infections in 16 renal transplant recipients and 16 healthy controls by virus isolation, serology, polymerase chain reaction (PCR) followed by dot blot hybridization. HHV-6 variant A was isolated from one renal transplant recipient. Seven patients (44%) and six controls (38%) had HHV-6 variant B DNA in their peripheral blood mononuclear cells. The prevalence of HHV-7 DNA was found to be the same in patients and controls (19%).

Virus-specific antibodies to Epstein-Barr virus, varicella-zoster virus and rubella virus in renal transplant patients with cytomegalovirus infections

Renal transplant patients with primary and recurrent cytomegalovirus (CMV) infection had higher antibody titres to Epstein-Barr virus viral capsid antigen (EBV-VCA-IgG) before and after transplantation than healthy blood donors. The geometric mean titres (GMT) of EBV-VCA-IgG were higher in renal transplant patients without CMV infection than in renal transplant patients with CMV infection. Four-fold or greater rises in EBV-VCA-IgG antibody were detected in six patients and a similar rise in antibody to EBV early antigen (EBV-EA-IgG) was detected in one other patient. IgM antibody to EBV-VCA (EBV-VCA-IgM) was detected in only three of these patients. EBV-EA-IgG was present in 39% patients and in 30% control subjects. IgG titres to varicella zoster virus (VZV-IgG) and rubella virus (rubella HI) were higher in patients without CMV infection compared to the patients with CMV infection. Raised titres were detected to VZV in five patients and to rubella virus in three patients. Reductions in antibody titre of four-fold or more were also detected in EBV-EA-IgG (one patient) and to rubella virus (one patient). Raised antibody titres to EBV, VZV, and rubella virus in renal transplant patients may indicate reactivation of these viruses without any symptoms.

Herpes simplex keratitis in renal transplant patients

Five out of 430 patients (1.16%) undergoing kidney transplantation developed an atypical clinical picture of herpetic dendritic keratitis within four weeks after surgery. It was manifested by multiple dendrites, located mainly in the corneal periphery or the limbus, developing in relatively uninflamed eyes. The response to acyclovir therapy was prolonged and took at least three weeks. Additionally, subepithelial infiltrates with ultimate scarring developed in all patients. Disciform keratopathy was not found. This clinical course is ascribed to the patients' immunosuppressed state.

Detection of cytomegalovirus-specific IGM in renal transplant recipients

We have compared two IgM-specific cytomegalovirus (CMV) antibody assays, an immunofluorescence assay (IFA-M) and an enzyme-linked antigen immunoassay (ELA-M), with an assay for CMV total antibody (ELISA) and viral culture for the detection of active CMV infection in renal transplant recipients. Of 75 patients (49 ELISA negative pretransplant, 26 ELISA positive), CMV-specific IgM was detected in 35 (27 ELISA negative pretransplant, 8 ELISA positive) using the IFA-M assay and in 25 (16 ELISA negative pretransplant, 9 ELISA positive) using the ELA-M test. Of the 25 patients identified as positive by ELA-M, 21 had positive viral cultures post-transplant, two seronegative patients had evidence of infection indicated by post-transplant seroconversion, and two patients were seropositive pretransplant but remained viral culture negative throughout the follow-up period. ELA-M and CMV total antibody ELISA detected primary infection in renal transplant recipients equally well, but ELA-M was found to be superior to ELISA and IFA-M for detecting reinfection and reactivation infections.

Epstein-Barr virus, cytomegalovirus, and other viral infections in children after liver transplantation

We studied 51 consecutive pediatric patients for the frequency and morbidity of viral infections after liver transplantation. The incidence of primary (67%) and reactivation (48%) Epstein-Barr virus (EBV) infections and reactivation (88%) cytomegalovirus (CMV) infection was comparable to that seen in adult transplant recipients. However, fewer pediatric than adult transplant recipients experienced primary CMV infection (P less than .01). Five (38%) of 13 CMV infections were symptomatic and included hepatitis, pneumonitis, enteritis, and mononucleosis. Two of 14 patients with primary EBV infection subsequently developed, at two months and two years after initial infection, an EBV-associated lymphoproliferative syndrome, and one of 10 patients with reactivated EBV infection developed a possible EBV-associated febrile encephalopathy. Other viruses causing infection in these children included herpes simplex virus, varicella-zoster virus, adenovirus, parainfluenza virus, respiratory syncytial virus, and rotavirus.

Epstein-Barr virus infections and DNA hybridization studies in posttransplantation lymphoma and lymphoproliferative lesions: the role of primary infection

Fourteen patients who developed B cell lymphomas or lymphoproliferative lesions after kidney, liver, heart, or heart-lung transplantation in Pittsburgh during 1981-1983 had active infection with Epstein-Barr virus (EBV) of the primary (six patients), reactivated (seven patients), or chronic (one patient) type. In transplant patients without tumors, the incidence of EBV infection was 30% (39 of 128). Only three of these patients had primary infections. Thus the frequency of active infection was significantly higher in patients with tumors, and patients with primary infections were at greater risk of developing tumors. Five of 13 tumors tested contained EBV nuclear antigen (EBNA) and nine of 11 contained EBV genomes detected by DNA-DNA hybridization with BamHI K, BamHI W, or EcoRI B cloned probes. All EBNA-positive tumors, except one, were also positive by hybridization. Only one tumor was negative for both EBNA and EBV DNA. These data suggest that EBV plays an etiologic role in the development of these lesions.

A population-based case-control study of EBV and other viral antibodies among persons with Hodgkin's disease and their siblings

The Epstein-Barr virus (EBV) has been consistently found to be associated with Hodgkin's disease (HD) in two ways: cases generally have elevated titer distributions of antibodies against the viral capsid antigen, and the occurrence of HD among persons with a history of EBV infectious mononucleosis is two or three times higher than expected. We evaluated this association by measuring the prevalence and level of antibodies against EBV and related viruses among 304 cases of HD interviewed in a population-based study in comparison to 285 of their siblings. The most significant finding was that antibody titers to the viral capsid antigen of EBV were elevated (greater than or equal to 1:320) in 39% of the cases and in only 14% of the sibling-controls; the relative risk adjusted for age and sex was 4.1. The geometric mean titer was three-fold higher among cases (175.6 vs. 58.1) Subjects who reported a history of IM had a higher distribution of titers than those who did not. Cases also had elevated titers against the early antigen of EBV - the D Component being most prominent. A significantly higher proportion of cases has elevated titers against CMV, relative risk = 3.4, but the prevalence of CMV antibody was relatively low and not consistently higher among cases. The findings support the hypothesis that EBV may play a role in the pathogenesis of HD among persons with elevated titers. The findings neither confirm nor deny a possible role of CMV.

The effect of the dosage of steroids on the incidence of cytomegalovirus infections in renal transplant recipients

In a retrospective survey of 92 cadaver renal transplant recipients, cytomegalovirus (CMV) infections were detected in 23 of 34 (68 per cent) patients treated with high doses of steroids but in only 27 of 58 (47 per cent) patients given low doses. Pretransplant blood transfusions were associated with both an improvement in one-year allograft survival-rates (P less than 0.05) and an increase in the incidence of CMV infections. When standardised for any transfusion effect, the incidence of CMV infections was significantly higher in those patients given high doses of steroids (P less than 0.05). In the same group of patients, moreover, CMV infections were associated with a statistically significant increase in the renal allograft survival-rate (P = 0.03).

Epstein-Barr virus-induced lymphoma in a cardiac transplant recipient

A monoclonal diffuse histiocytic lymphoma developed during the course of a serologically documented primary Epstein-Barr virus infection in a 22-year-old cardiac transplant recipient taking cyclosporine and prednisone. Throat washings revealed the virus at tumor presentation, and the tumor was shown to contain Epstein-Barr nuclear antigen-positive cells and the viral genome. Prolonged inversion of the T cell helper/suppressor ratio was demonstrated. A brief course of acyclovir appeared to halt viral shedding in the throat but had no apparent effect on the tumor.

Failure to demonstrate concomitant antibody changes to viral antigens other than Epstein-Barr virus (EBV) during or after infectious mononucleosis

A search for antibody rises to viral antigens other than to Epstein-Barr virus, the causative agent, has been carried out in serial serum samples from 82 patients with infectious mononucleosis (IM). Fourfold or greater rises in titer rarely occurred and did did not cluster in time. No rises occurred to cytomegalovirus, only 1.2 percent to herpes simplex virus, and 8.5 percent to varicella zoster virus. Rises to measles antibody were found in 7.5 percent of patients and to rubella in 10.4 percent; these may represent natural infections or immunizations. A few patients also showed rises to respiratory viruses but there was no apparent connection to IM.

A prospective study of cytomegalovirus and herpes simplex virus disease in renal transplant recipients

A prospective study of 84 renal graft recipients demonstrated cytomegalovirus (CMV) disease after transplantation in 37% of patients. Reactivation infection was found in 20 of 44 patients (46%) who were seropositive for CMV prior to transplant and primary CMV disease occurred in 11 of 40 (28%) initially seronegative patients. Nearly all cases of primary disease (91%) were associated with symptoms and in these cases CMV was probably acquired via the donated kidneys. Only 35% of the reactivation infections were associated with clinical symptoms. Actuarial life tables indicated that CMV disease did not reduce the length of graft survival. Herpes simplex virus (HSV) infections were diagnosed in 44 (52%) of the patients and included a fatal case of disseminated disease associated with hepatitis.

Mucocutaneous herpes simplex virus infections in immunocompromised patients. A model for evaluation of topical antiviral agents

Forty-three immunocompromised patients with progressive cutaneous herpes simplex virus infections were studied in a double-blind, placebo-controlled evaluation of topically applied acyclovir. Patients were randomized and 22 received acyclovir and 21 placebo; medications were applied four times daily for 10 days. Both study populations were balanced for all demographic characteristics. Acyclovir therapy resulted in no median differences in time to total healing compared with placebo responses, p = 0.13. However, those patients who received the acyclovir ceased shedding virus more rapidly, p less than 0.001, and lost pain more readily, p = 0.04, than placebo counterparts. Neither group experienced adverse effects. Because of the protracted nature of mucocutaneous herpes simplex infections in these patients, the immunocompromised host provides a good model for evaluation of topical antiviral therapy.

A prospective study of oropharyngeal excretion of Epstein-Barr virus in renal homograft recipients

This prospective study was undertaken to examine the incidence of oropharyngeal excretions of Epstein-Barr virus (EBV) in the period after transplantation in human renal allograft recipients. Throat gargles from 23 recipients were tested for EBV. Five patients were already EBV excretors when the first specimens were tested. Of the remaining 18 patients 15 converted to positive within the first 7 months following transplantation. Three patients never excreted EBV in their throat gargles. This prospective study showed that 15/18 (83%) renal homograft recipients acquired active EBV infection (as indicated by excretion of EBV) after transplantation; 10/15 (66%) acquired active infection between 3-7 months after transplantation. We conclude that renal homograft recipients are highly susceptible to active EBV infection especially after the second month of transplantation.

Cell-mediated immunity in mice with primary, secondary and latent herpes simplex virus infection

Cell mediated immunity was studied by a cytopathic effect inhibition assay in mice infected in the ear with herpes simplex virus type 1 (HSV 1). Activity appeared rapidly, reaching a high level 6 days after primary infection. It had fallen 10 days after infection and was undetectable during latency, 3-5 weeks after infection. The activity reappeared even more rapidly and strongly after reinoculation with the virus, but stimuli designed to induce recurrent disease did not induce clinical disease in the animals and no activity was detected in them. The activity, which was specific for HSV, was shown to be mediated by T-lymphocytes.

Gastric cytomegalovirus infection in bone marrow transplant patients: an indication of generalized disease

Cytomegalovirus infection in immunosuppressed patients is well known. It usually appears as an interstitial pneumonitis that may progress to a disseminated viral infection. The authors report on two patients who, after bone marrow transplantation, had signs and symptoms of gastric ulceration as the initial manifestation of cytomegalovirus infection. Both died with disseminated cytomegalovirus infection. Though gastric presentation is unusual for cytomegalovirus infection, epigastric pain and gastrointestinal hemorrhage in a bone marrow transplant patient may herald a potentially lethal viral infection.

Presence of elevated antibody titres to Epstein-Barr virus before Hodgkin's disease

Sera taken 12 and 21 months before the diagnosis of Hodgkin's disease in two patients showed higher antibody levels to several Epstein-Barr-virus (EBV) antigens than did sera from eight matched controls. In one case the titres of all EB antibodies except that to nuclear antigen were raised in a serum sample obtained 45 months after the diagnosis was made. Antibody levels to herpes simplex, cytomegalovirus, and varicella zoster viruses were normal in both cases. A third patient with histiocytic lymphoma had normal EBV and other herpes antibody titres in a serum sample taken 40 months before diagnosis.

Biology of mouse thymic virus, a herpesvirus of mice, and the antigenic relationship to mouse cytomegalovirus

Mouse thymic virus (TA) is a herpesvirus which produces extensive necrosis of the thymus of newborn mice 7 to 14 days after infection. Infectious virus can be recovered from the thymus for only 10 days after infection, with highest titers occurring between days 5 and 7. In mice 5 days old or less, TA infects thymus cells and produces massive necrosis. TA also infects the salivary glands and persists as a chronic infection. Newborn mice infected with TA have no detectable humoral immune response. Infected adult mice respond, and humoral antibody is detected 7 days after infection. Titers are maintained for months thereafter. Regardless of the age of the mice inoculated with TA, persistent infection was established in the salivary glands, but no evidence for thymus involvement was observed when adults were infected. TA does not cross-react serologically by immunofluorescent, complement fixation, or virus neutralization tests with mouse cytomegalovirus; however, interestingly, the epidemiology of the two herpesviruses are similar. Both mouse cytomegalovirus and TA were isolated from the same animals in populations of laboratory and wild mice. Evidence of infection with mouse cytomegalovirus and TA were most apparent by virus isolations, since humoral antibody responses are rarely observed. All strains of mice tested were susceptible to TA infection. However, in some strains maximum necrosis occurred at 7 days, compared with 10 to 14 days for other strains. The difference in age susceptibility and the target tissue of thymus in newborn mice suggests that TA is a model herpesvirus for studying the effects of viral infections on humoral and cell-mediated immunological functions.

Comparison of rates of virus isolation from leukocyte populations separated from blood by conventional and Ficoll-Paque/Macrodex methods

One hundred fifty-two blood specimens, largely from immunocompromised patients, were collected in heparinized Vacutainer tubes and divided into paired aliquots of equal volume. Buffy-coat preparations, containing mixed leukocyte and separate mononuclear and polymorphonuclear leukocyte populations were obtained by treatment of blood with conventional and Ficoll-Paque/Macrodex (F-P/M) methods. The development of cytopathic effect in monolayers of WI-38 fibroblasts inoculated with cell suspensions derived from the two methods was used to assess virus infectivity. Twice as many virus isolations were obtained using F-P/M. Of those viruses isolated by both conventional and F-P/M, the development of cytopathic effect was more extensive using the latter method. Moreover, a greater variety of viruses was isolated using F-P/M method, as compared to the conventional method. The F-P/M method is no more time consuming than conventional procedures, is readily adaptable for use in the diagnostic virology laboratory, requires only minimal additional cost, and is a particularly suitable and effective means of monitoring viremia.

General features of persistent virus infections

Persistent virus infections are discussed from the virus point of view in terms of the bodily sites in which the infection persists. Glands and body surfaces are thought to be significant because they give the virus protection at the topographical level from immune forces, and because they are appropriate sites for the shedding of virus to the exterior. Germ cells are relevant sites because infection can thus be transmitted vertically from generation to generation in the host. The central nervous system, however, is generally a 'dead end' from which there is no shedding to the exterior. Persistance in blood may be relevant when continued arthropod transmission becomes possible. Most persistent viruses infect lymphoreticular tissues, and this is interpreted by suggesting that it results in an impaired immune response to the infecting virus, which in turn favours persistence. It is suggested that the biological function of virus transformation and the integration of viral into host cell DNA is that it enables the infection to persist in the host and undergo reactivation. Papovaviruses, adenoviruses and oncornaviruses are considered from this point of view.

A longitudinal study of the serological and virological status of 18 women infected with cytomegalovirus

18 women, of known seropositivity, have been followed for between 18 and 66 months (mean 50.2 months) for viral excretion and serological changes. CMV was isolated from 58/146 (39.7 per cent) cultures from various sites, mostly cervix. A total of 129 sera were obtained and each was titrated in the late antigen, early antigen and anti-complement immunofluorescence assays, as well as the complement fixation and microneutralisation tests. From 3 women virus was consistently re-isolated, from 3 others virus was never re-isolated and the remaining 12 women excreted virus intermittently during the period of study. No significant changes in antibody titres could be detected by any of the 5 serological assays in any woman during periods of viral excretion. This suggests that local reactivation of latent CMV infection is not associated with a demonstrable systemic antibody response. Inter-assay correlations were sought for each of the 10 possible combinations of pairs of tests. Significant correlations were found for most pairs of tests, with the notable exception fo those involving the early antigen test. This confirms that antibodies detected in this assay are distinct from those detected by the other 4 serological assays.

Cytomegalovirus infection and graft survival in renal graft recipients

We have studied 85 patients who received a renal transplant for CMV infection as well as for herpes simplex (HSV), herpes zoster (HZ), measles, mumps, rubella and hepatitis B. We found no evidence of primary or secondary infections for the non herpetic viruses except for hepatitis B infection that occurred in 17 per cent of the patients. CMV infection occurred in 87 per cent of the patients while antibody rises to HZ and HSV occurred in 30 and 13 per cent of the patients, respectively. The CMV infections occurred 2 to 4 months after the transplantation (mean time 11.1 weeks) and seemed to trigger the first episode of renal rejection that occurred earlier in the CMV infected group (mean time 12.1 weeks) than in the uninfected group (mean time 18.6 weeks). This difference in time is highly significant, p less than 0.001). However these CMV injections did not decrease the longterm survival of the grafted kidneys.