Predictions and associations of fatigue syndromes and mood disorders that occur after infectious mononucleosis

BACKGROUND

Certain infections can trigger chronic fatigue syndromes (CFS) in a minority of people infected, but the reason is unknown. We describe some factors that predict or are associated with prolonged fatigue after infectious mononucleosis and contrast these factors with those that predicted mood disorders after the same infection.

METHODS

We prospectively studied a cohort of 250 primary-care patients with infectious mononucleosis or ordinary upper-respiratory-tract infections until 6 months after clinical onset. We sought predictors of both acute and chronic fatigue syndromes and mood disorders from clinical, laboratory, and psychosocial measures.

FINDINGS

An empirically defined fatigue syndrome 6 months after onset, which excluded comorbid psychiatric disorders, was most reliably predicted by a positive Monospot test at onset (odds ratio 2.1 [95% CI 1.4-3.3]) and lower physical fitness (0.35 [0.15-0.8]). Cervical lymphadenopathy and initial bed rest were associated with, or predicted, a fatigue syndrome up to 2 months after onset. By contrast, mood disorders were predicted by a premorbid psychiatric history (2.3 [1.4-3.9]), an emotional personality score (1.21 [1.11-1.35]), and social adversity (1.7 [1.0-2.9]). Definitions of CFS that included comorbid mood disorders were predicted by a mixture of those factors that predicted either the empirically defined fatigue syndrome or mood disorders.

INTERPRETATION

The predictors of a prolonged fatigue syndrome after an infection differ with both definition and time, depending particularly on the presence or absence of comorbid mood disorders. The particular infection and its consequent immune reaction may have an early role, but physical deconditioning may also be important. By contrast, mood disorders are predicted by factors that predict mood disorders in general.

Incidence, risk and prognosis of acute and chronic fatigue syndromes and psychiatric disorders after glandular fever

BACKGROUND

The role of viruses in the aetiology of both chronic fatigue syndrome (CFS) and depressive illness is uncertain.

METHOD

A prospective cohort study of 250 primary care patients, presenting with glandular fever or an ordinary upper respiratory tract infection (URTI).

RESULTS

The incidence of an acute fatigue syndrome was 47% at onset, after glandular fever, compared with 20% with an ordinary URTI (relative risk 2.3, 95% CI 1.3-4.1). The acute fatigue syndrome lasted a median (interquartile range) of eight weeks (4-16) after glandular fever, but only three weeks (2-4) after an URTI. The prevalence of CFS was 9-22% six months after glandular fever, compared with 0-6% following an ordinary URTI, with relative risks of 2.7-5.1. The most conservative measure of the incidence of CFS was 9% after glandular fever, compared with no cases after an URTI. A conservative estimate is that glandular fever accounts for 3113 (95% CI 1698-4528) new cases of CFS per annum in England and Wales. New episodes of major depressive disorder were triggered by infection, especially the Epstein-Barr virus, but lasted a median of only three weeks. No psychiatric disorder was significantly more prevalent six months after onset than before.

CONCLUSIONS

Glandular fever is a significant risk factor for both acute and chronic fatigue syndromes. Transient new major depressive disorders occur close to onset, but are not related to any particular infection if they last more than a month.

Evaluation of specific herpes DNA viruses in idiopathic megarectum and idiopathic megacolon

PURPOSE

The aetiology of idiopathic megarectum and idiopathic megacolon is unknown. A previous study in patients with chronic idiopathic intestinal pseudo-obstruction, a condition also associated with a dilated gut, identified the possible involvement of herpes viruses. This study therefore aimed to determine whether these viruses may also be implicated in the pathogenesis of these conditions.

METHODS

Resected large bowel from three patients with idiopathic megarectum and three patients with idiopathic megacolon were studied. Histology for viral inclusions and nested polymerase chain reaction (PCR) using specific primers for cytomegalovirus, Epstein-Barr virus, herpes simplex virus type 1 and varicella zoster virus was performed. DNA was extracted from paraffin-embedded blocks by proteinase K and phenol chloroform extraction.

RESULTS

Viral inclusions were not seen. PCR failed to identify DNA of the four herpes viruses tested.

CONCLUSION

Patients with idiopathic megarectum or idiopathic megacolon may have subtle abnormalities of the enteric innervation, but these do not appear to be attributable to the neurotropic effects of the herpes viruses studied.

DNA viruses in the pathogenesis of sporadic chronic idiopathic intestinal pseudo-obstruction

BACKGROUND

Hereditary forms of chronic idiopathic intestinal pseudo-obstruction (CIIP) are well described but the aetiology of most cases of sporadic CIIP is unknown.

AIM

To determines whether herpes viruses can persist in the gastrointestinal tract, thereby implicating them in the pathogenesis of CIIP.

METHODS

Twenty one specimens of small and large intestine from 13 patients with CIIP (eight visceral myopathy, three visceral neuropathy, two undifferentiated), and 12 patients operated on for colorectal cancer (controls) were examined for evidence of Herpesvirus DNA (cytomegalovirus, Epstein-Barr virus (EBV), herpes simplex virus type 1, and varicella zoster virus) by nested polymerase chain reaction (PCR) and in situ DNA hybridisation (ISH) to localise signal to the muscularis propria or myenteric plexus.

RESULTS

Screening with nested PCR produced three patients with positive results. One patient with an inflammatory visceral neuropathy had EBV detected in the small intestine by PCR, and ISH demonstrated localisation to neurones in the myenteric plexus. A patient with a visceral myopathy had EBV DNA in both the small and large intestine; and one patient with a visceral neuropathy had small intestine positive for CMV DNA (both negative by ISH). No control tissue was positive for any virus.

CONCLUSIONS

In individual patients there appears to be evidence linking a viral aetiology to sporadic CIIP. The role of neurotropic viruses in acute and chronic motility disturbances needs further study.

The validity and reliability of the fatigue syndrome that follows glandular fever

The validity and reliability of an empirically defined fatigue syndrome were tested in a prospective cohort study of 245 primary care patients, with glandular fever or an upper respiratory tract infection. Subjects were interviewed three times in the 6 months after onset. Subjects with the empirically defined fatigue syndrome were compared with those who were well and those who had a psychiatric disorder. The validity of the fatigue syndrome was supported, separate from psychiatric disorders in general and depressive disorders in particular. Only 16% of subjects with the principal component derived fatigue factor also met criteria for a psychiatric disorder (excluding pre-morbid phobias). Compared with subjects with psychiatric disorders, subjects with the operationally defined fatigue syndrome reported more severe physical fatigue, especially after exertion, were just as socially incapacitated, had fewer mental state abnormalities, and showed little overlap on independent questionnaires. A more mild fatigue state also existed. Both fatigue syndrome and state were more reliable diagnoses over time than depressive disorders. The empirically defined syndrome probably is a valid and reliable condition in the six months following glandular fever.

The existence of a fatigue syndrome after glandular fever

This prospective cohort study was designed to test whether a distinct fatigue syndrome existed after the onset of glandular fever. Two hundred and fifty primary care patients, with either glandular fever or an ordinary upper respiratory tract infection (URTI) were interviewed three times in the 6 months after the clinical onset of their infection. At each interview a standardized psychiatric interview was given and physical symptoms were assessed. There were 108 subjects with and Epstein-Barr virus (EBV) infection; 83 subjects had glandular fever not caused by EBV and 54 subjects had an ordinary URTI. Five subjects were excluded because they had no evidence of an infection. Principal components analyses of symptoms supported the existence of a fatigue syndrome, particularly in the two glandular fever groups. The addition of symptoms not elicited by the standard interviews gave the full syndrome. This included physical and mental fatigue, excessive sleep, psychomotor retardation, poor concentration, anhedonia, irritability, social withdrawal, emotional lability, and transient sore throat and neck gland swelling with pain. A fatigue syndrome probably exists after glandular fever.

The activity of candidate virucidal agents, low pH and genital secretions against HIV-1 in vitro

The effect of low pH, normally present in the female genital tract, on HIV viability was examined. HIV is more acid stable than previously reported with no substantial reduction in infectivity occurring until pH levels are reduced below 4.5. The virucidal activity of 3 topical spermicides and chlorhexidine was assessed in vitro using previously established and newly modified assay systems. None of the agents tested had a selectivity index (SI) greater than 5.2. Semen and cervical secretions were assessed for their ability to inhibit HIV-1. While no virucidal effect was found in the latter, seminal fluid was found to have significant activity against HIV-1 and a SI of approximately 50.

Seroprevalence of antibodies to human herpesviruses in England and Hong Kong

The age-related prevalence of antibodies to herpesviruses was compared in England and Hong Kong. Altogether 327 sera from England and 266 sera from Hong Kong were tested for antibodies to herpes simplex virus (HSV), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), and human herpesvirus 6 (HHV-6). Herpesvirus infections were common in both countries but generally were acquired earlier and were more prevalent in Hong Kong. Over 90% of children in Hong Kong were infected with VZV, EBV, and HHV-6 by 8 years of age. HSV and CMV were the least prevalent childhood infections in both countries, although, 30-40% of babies in Hong Kong became infected during the first year of life. CMV infections were rare throughout childhood in the English cohort. Overcrowding and early attendance at kindergarten may aid more efficient and earlier transmission of herpesvirus in Hong Kong. The high prevalence of CMV in particular may have implications for the management of young pregnant women and organ transplant recipients in Hong Kong.

DNA amplification by the polymerase chain reaction to detect sub-clinical Pneumocystis carinii colonization in HIV-positive and HIV-negative male homosexuals with and without respiratory symptoms

Pneumocystis carinii colonization was studied in 90 men using the polymerase chain reaction. These comprised ten heterosexual controls; ten HIV-seronegative homosexual controls; 20 HIV-seropositive homosexuals with blood CD4 count > 400 x 10(6) l-1; 20 HIV-seropositive homosexuals with CD4 < 400 x 10(6) l-1; ten HIV-seropositive homosexuals with CD4 < 60 x 10(6) l-1 receiving PCP chemoprophylaxis; and 20 HIV-seropositive homosexuals with respiratory symptoms but without PCP. Induced sputum was obtained from all but the last group, who had bronchoalveolar lavage, and all specimens were tested for P. carinii using the polymerase chain reaction. The first four groups received no pneumocystis chemoprophylaxis, and all but the last group were asymptomatic. P. carinii colonization did not occur in the two control groups. P. carinii colonization rates were significantly different in the CD4 > 400, CD4 < 400, and CD4 < 60 groups (10%, 20%, and 40% respectively) (P < 0.025). Two patients (one each from CD4 < 400 and CD4 < 60) developed PCP 4-6 weeks after sputum induction, both had previously had high levels of P. carinii on sputum induction. Two patients from the CD4 < 400 group had high levels of P. carinii but did not develop PCP. In the symptomatic group, two subjects had low levels of P. carinii, but did not develop PCP. We have demonstrated P. carinii colonization in HIV-seropositive homosexuals in association with a low peripheral CD4 count. The polymerase chain reaction may be a useful technique for determining the need and efficacy of anti-pneumocystis chemoprophylaxis.

Growth characteristics of human herpesvirus-6: comparison of antigen production in two cell lines

In order to optimize viral antigen production, the growth characteristics of human herpesvirus-6 (HHV-6) (strain AJ) were studied in two cell lines: HSB-2 and JJHAN. The cells were infected with different multiplicities of infection (moi) and viral growth was monitored by appearance of cytopathic effect (CPE), total and viable cell count, immunofluorescence test, immunoblotting, and electron microscopy. Although > or = 70% of JJHAN cells showed CPE when infected at high moi, only 5% of the cells contained viral antigens when tested with immunofluorescence. In contrast the percentage of cells showing fluorescence in HSB-2 cells reached > or = 30% when infected at > or = 1:50. More than 10 polypeptides of molecular weight ranging between 31-140 kD appeared in the HSB-2 cultures by immunoblotting while only 3 polypeptides were detected in the JJHAN cultures at high moi. Different stages of virus maturation were seen in the HSB-2 cells by electron microscopy but the replication of the virus in JJHAN cells appeared to be restricted. For the purpose of antigen production the optimal conditions for the AJ strain of HHV-6 were found to be culturing in HSB-2 cells at a concentration of 1:25-1:50 infected to uninfected cells and harvesting after 7 days.

An in-depth study of Crohn's disease in two French families

BACKGROUND

Two French families were investigated. In the first a husband, wife, and 4 children had Crohn's disease; in the second 7 of 11 children had the disease. There was no history of Crohn's disease in antecedent generations and no linkage to HLA haplotypes.

METHODS

Methods included family interviews; review of medical records, radiographs, and pathology slides; serology; selective stool culture; enzyme-linked immunosorbent assay for fecal viral detection; and immunocytochemistry.

RESULTS

In both families multiple cases occurred among siblings in 7-13-month periods. There appeared to be a 4-8-year recurrence of new disease in both families. Radiographs showed a remarkable similarity in the pattern of disease, confined to distal ileum and cecum, in the members of family 1. Examination for pathology showed granulomas in all 8 patients for whom tissues were available. Acid-fast organisms or Campylobacter-like organisms were not found in tissue sections, and immunocytochemistry was negative for mycobacteria and Yersinia. Stool cultures were negative for mycobacteria, Yersinia, and Mycoplasma. Torovirus and coronavirus antigens were not found in stool. Serology was negative for antibodies to Brucella, Yersinia, influenza, and three enteropathogenic viruses of animals.

CONCLUSIONS

The circumstances and data suggest that an infectious microorganism is responsible for these clusterings of Crohn's disease.

Epstein Barr virus (EBV) encoded small RNAs: targets for detection by in situ hybridisation with oligonucleotide probes

AIMS

To develop a rapid, sensitive, and specific non-isotopic in situ hybridisation (NISH) procedure for the detection of Epstein-Barr virus in formalin fixed, paraffin wax embedded tissues.

METHODS

Two low molecular weight RNAs, designated EBER-1 and EBER-2 (Epstein-Barr encoded RNA), were used: cells latently infected with EBV secrete large amounts of EBERs. The method uses digoxigenin labelled anti-sense oligonucleotides, corresponding to sequences in EBER-1 and EBER-2.

RESULTS

The use of these probes, in conjunction with high temperature microwave denaturation, ensured that the technique was considerably more sensitive than other in situ hybridisation techniques for detecting EBV. Furthermore, the hybridisation signal was morphologically distinct in that only the nucleus and not the nucleolus give a positive signal. No cross-hybridisation was observed with cells infected with other lymphotropic herpes viruses.

CONCLUSION

The sensitivity, simplicity, and rapidity of this technique make it ideal for diagnostic use, and for studies investigating the role of this virus in neoplastic disease.

Presence of Epstein-Barr virus in Hodgkin's disease is not exclusive to Reed-Sternberg cells

Thirty-three cases of Hodgkin's disease (HD) have been studied for the presence of Epstein-Barr virus (EBV) using a novel nonisotopic in situ hybridization procedure, based on the detection of Epstein-Barr encoded RNAs with oligonucleotide probes. An intense and morphologically distinct nuclear staining, sparing the nucleolus was seen in a total of 12 cases (36%). In six of these cases, the signal was located to the Hodgkin and Reed-Sternberg cells (HR-S); in the other six positive cases, the signal was observed only in the non-neoplastic small lymphocytes. These lymphocytes were few in number and immunocytochemistry results were consistent with a B-cell phenotype. The presence of EBV in those cases characterized by nuclear staining of small lymphocytes was confirmed by the polymerase chain reaction (PCR) analysis. The authors report the detection of EBV in small lymphocytes in HD by in situ hybridization and discuss the implications of these findings in relation to the proposed etiologic association between EBV and HD.

Inhibitory effects of urine on the polymerase chain reaction for cytomegalovirus DNA

The inhibitory effects of urine samples taken from neonates and older children, some of which were known to be infected with cytomegalovirus, on the polymerase chain reaction (PCR) were investigated. Urea was the major inhibitory component of urine and inhibited the PCR at a concentration of more than 50 mM. Urine samples from older children were more inhibitory than those from neonates. This correlated with the higher concentration of urea generally found in urine samples from older children compared with neonatal urines. Two of 13 neonatal urine samples, however, were inhibitory despite low urea concentrations--presumably due to metabolites derived from parenteral nutrition. The inhibitory effects of urine were effectively removed by simple dialysis or ultrafiltration. The sensitivity and specificity of PCR for detecting cytomegalovirus DNA in urine were further improved by using "nested" primers and a modified PCR protocol entailing the use of reduced reactants in the first 20 cycles of a two-stage 50 cycle PCR.

Simplified procedures for applying the polymerase chain reaction to routinely fixed paraffin wax sections

The polymerase chain reaction was applied to the analysis of DNA contained in archival paraffin wax embedded material. DNA suitable for the reaction was obtained from these tissues by simple extraction methods, without previous dewaxing of tissue sections. When compared with unfixed material, the reaction efficiency was compromised, so that an increased number of amplification cycles were required to produce equivalent amounts of amplified product. This in turn led to an increase in amplification artefacts, which can be minimised by a simple modification of the standard reaction. Amplification of relatively large DNA fragments was not always successful, and it seems prudent to bear this in mind when designing oligonucleotide primers which are to be used for the amplification of archival material. The efficiency of the procedure can be improved by dividing the amplification cycles into two parts: this reduces the amount of reagent needed, is relatively simple and inexpensive, and can be performed in one working day.

Antibody avidity following varicella-zoster virus infections

The avidity of IgG antibodies following varicella-zoster virus (VZV) infections was investigated using urea treatment of antigen-bound serum antibody by indirect radioimmunoassay (RIA) and immunoblotting techniques. Sequential sera from 16 patients with varicella and 17 patients with zoster were tested, as well as sera from 80 seropositive individuals without a recent history of VZV disease. Both types of assay showed that low-avidity antibodies predominate early after primary infection, but that antibody avidity increases markedly during convalescence. Using RIA, all sera taken up to 12 weeks after the onset of varicella showed greater than 50% reduction in antibody titre after treatment with 8 M urea but thereafter the proportion of urea resistant antibody increased with time. In contrast, after recurrent infection, high avidity antibodies were found to predominate at all times. Only 6 of 47 sera tested from zoster cases showed greater than 30% reduction after urea treatment and all these were taken within 2 weeks after onset of rash. Immunoblotting also showed that the highly immunogenic p32/p36 nucleoproteins appear to induce predominantly low avidity antibodies, even after recurrent VZV infection. The results of this study indicate that treatment with 8 M urea in RIA for IgG antibodies may be a simple and reliable method for distinguishing primary and anamnestic antibody responses against VZV.

Protein blotting: ten years on

Protein blotting was originally described in 1979 as an outgrowth of nucleic acid techniques, and received its commonly used designation of 'Western' blotting in 1981. The use of the technique to render electrophoresed proteins accessible for further analysis has found many roles, the most prominent being subsequent reaction with antibodies or antisera, which has many clinical and research applications. Since the initial development of the system there have been many changes to the techniques involved, but the basic principles remain unaltered. This review discusses these changes, and also provides a summary of current techniques.

A prospective study of viral and mycoplasma infections in chronic inflammatory bowel disease

Seventy-two children with chronic inflammatory bowel disease were investigated for infections with various viruses and Mycoplasma pneumoniae, Chlamydia psittaci, and Coxiella burnetii to determine whether these pathogens are associated with acute onset exacerbations. Altogether 54 infections were identified serologically, of which 23 (42.6%) were associated with exacerbations. This corresponded to 24.2% of the recorded exacerbations during the study period. The respiratory pathogens accounted for 59.3% of the infections and 43.8% of these were associated with gastrointestinal symptoms. This is consistent with the observation that up to 40% of the exacerbations were associated with symptoms of antecedent or concurrent infection, most commonly involving the respiratory tract. Rubella virus, Epstein-Barr virus, and adenovirus were associated with acute exacerbations in 5 children. Thus, common pathogens were frequently associated with exacerbations and account for a large proportion of the commonly reported symptoms of a concurrent infection. The possible causal relationship between these pathogens and exacerbation of inflammatory bowel disease is discussed. Reactivation of latent herpesviruses was identified in 4 children with active disease and indicates that the converse relationship may also occur.

Lipoproteins of varicella-zoster virus

Human fibroblast cells infected with varicella-zoster virus (VZV) showed a slight increase in lipoprotein synthesis, with the production of two major viral lipoproteins, as detected by radioimmunoprecipitation (RIP). Three bands of Mr 73,000, 90,000 and 97,000 were identified as forms of the VZV gpI glycoprotein. All three incorporated both palmitic and myristic acid, and were shown by thin-layer chromatography to contain myristic, palmitic and stearic acids. A very strong band corresponding to 7,000 Mr, which may represent the product of VZV gene 49, was detected after RIP and in VZV-infected cells, and was shown to contain almost entirely myristic acid. Several minor bands were also detected. The possible functions of the lipoproteins are discussed.

Antibody responses in recipients of varicella vaccine assayed by immunoblotting

Sera taken from 35 children with cancer who had been vaccinated with live varicella vaccine were assayed using immunoblotting for the presence of IgG class antibodies to proteins present in varicella-zoster virus (VZV)-infected cells. Sera from 23 of these patients were also assayed for IgM class antibodies. The patterns of immunoreactivity observed for these patients following vaccination were substantially weaker and more variable than those detected following natural VZV infection in otherwise healthy individuals. The IgG responses detected following vaccination involved up to 10 protein bands between 28 and 188 kDa. Bands were particularly frequent in the 78-96 kDa region. IgM responses involved up to 10 bands between 28 and 114 kDa, with the bands in the 78-96 kDa region and at 32-36 kDa being detected most frequently. Repeated vaccination generally produced a stronger IgG antibody response than did single vaccination, and subsequent exposure of vaccinees to natural VZV infection resulted in an increased level of reactivity for IgG antibodies, but not for IgM. Similar reaction patterns were obtained with sera from vaccinees when the vaccine virus and wild-type VZV were used as antigens. Immunoblotting showed good correlation with indirect radioimmunoassay for the detection of a vaccine-induced IgG response.

Discordant results obtained on testing sera from immunocompromised patients for cytomegalovirus IgG by enzyme-linked immunosorbent assay and radioimmunoassay

The investigation of sera from immunocompromised patients for antibody to CMV by ELISA, RIA, immunofluorescence (IF) and complement-fixation (CF) revealed discrepancies that reflected differences in test specificity rather than sensitivity and suggested that for the long-term serological follow-up of such patients it would be advisable not to rely on only a single assay procedure.

Detection of specific IgM in varicella and herpes zoster by antibody-capture radioimmunoassay

A simple and sensitive M antibody-capture radioimmunoassay (MACRIA) is described which utilizes crude commercial VZV antigen and a single monoclonal anti-VZV antibody. This was compared to the immunofluorescence (IF) test for IgM antibody and was used to study IgM responses in sera from 261 patients with varicella and 220 patients with herpes zoster. With MACRIA, IgM antibodies were detected in all patients with varicella. The IgM antibodies appeared shortly after onset of rash, reached peak levels between 1 and 4 weeks after onset and then declined to low or undetectable levels in most, though not all, patients after 3 months. IgM antibodies were also detected in 98.2% of patients with herpes zoster, but the levels of IgM were significantly lower than after varicella and there was wider individual variation both in magnitude and duration of the IgM responses, in some cases only lasting 2-3 weeks. Comparison between MACRIA and IF showed good agreement in the detection of IgM antibodies following varicella. Discordant results were obtained with 13% of sera, of which 81% were taken either early or late after onset of rash and contained very low IgM levels. In contrast, 62 (28%) of the 220 sera from patients with zoster gave discordant results in the two tests, all except five being MACRIA-positive but IF-negative. The largest proportion of discordant results were obtained with sera taken more than 3 months after onset of rash, but 18 (29%) contained high IgM levels and were taken during the period of peak IgM responses. The diagnostic applications of the VZV MACRIA are discussed.

Serological responses in varicella and zoster assayed by immunoblotting

Acute and convalescent zoster sera taken from 11 patients with varicella and 12 patients with zoster were assayed using immunoblotting for the presence of IgG- and IgM-class antibodies to proteins present in varicella-zoster virus-infected cells. All patients exhibited a detectable virus-specific response with both antibody classes. The IgG responses involved up to 28 protein bands between 28 and 255 kilodaltons (kDa). The reactivity was particularly strong in the 78-114-kDa region, with additional bands observed with all patients at 32, 35, 66, and 220 kDa. This pattern of reactivity typically developed more slowly and was weaker and more variable in patients with varicella compared to those with zoster. The reactivity of IgM antibodies in immunoblotting was similar after varicella and after zoster. Individual sera showed up to 25 bands, with the major reactivity being directed against the 78-96-kDa region and two bands at 32 and 35 kDa. Some differences were apparent between the primary and anamnestic responses with both IgG and IgM antibodies, but this did not allow reliable discrimination of the two types of infection.

Reduction in immunoreactivity of varicella-zoster virus proteins induced by mycoplasma contamination

During the study of protein differences between several strains of varicella-zoster virus (VZV), two of the strains were found to be contaminated with Mycoplasma hyorhinis. Polyacrylamide gel electrophoresis showed fourteen extra bands present in MRC5 fibroblasts infected with these strains compared to other strains of VZV. A more striking difference was observed when infected cultures were used as antigens in immunoblotting. Certain viral proteins, corresponding in molecular weight to the viral glycoproteins, showed greatly reduced immunoreactivity. Experimental contamination of a mycoplasma-free strain of VZV with the glucose fermenting M. hyorhinis produced similar effects on immunoreactivity, while contamination with the arginine-hydrolysing M. orale produced no detectable effects. Given these data, it appears likely that the glucose-fermenting species induced significant changes in the VZV glycoproteins, possibly by depletion of sugars or interference in glycosylation pathways. The implications of this are discussed.

Efficacy of varicella vaccine in patients with solid tumours

Thirty nine children with malignant disease and without antibodies to varicella zoster virus were immunised with a live Oka strain varicella vaccine. Seroconversion was shown in 24 of those who were vaccinated but five of 18 who responded to the vaccine who were followed up for over six months subsequently lost their antibodies. Of 10 children who were revaccinated, nine responded to the second dose but three lost their antibodies within six months to two years. Four children developed reactions related to the vaccine, one local and three generalised, but all these were transitory and of no clinical concern. Nine of those who were vaccinated, including four who did not respond to the vaccine, have subsequently had close exposure to varicella but none has developed the disease.

The effect of staining on the immunoreactivity of nitrocellulose bound proteins

It was found that Coomassie blue staining of proteins electroblotted onto nitrocellulose resulted in a significant decrease in subsequent immunoreactivity, relative to unstained proteins. This was not uniform, and resulted in distortion of the pattern detected by immunoreaction as well as an overall decrease in sensitivity. Staining with amido black resulted in no such alteration. Additionally, it was observed that amido black is completely leached from the nitrocellulose strip during immunoreaction, whereas no leaching is apparent with Coomassie blue. This may contribute to the observed effect of staining on immunoreactivity.

Screening tests for antibodies to cytomegalovirus: an evaluation of five commercial products

Four hundred and ninety two samples of serum from blood donors were screened for the presence of antibodies specific to cytomegalovirus using radioimmunoassay, a modified complement fixation test, and five commercially available tests: the Cetus CMV IHA, Abbott CMV total AB EIA, Cytomegalisa Stat EIA, Enzygnost EIA, and Virenz G-CMV EIA. A wide variation in results was found, with only 53.5% of the sera giving total concordance by all methods. Rates of seropositivity in the different tests ranged from 34.9% to 59.3%, with sensitivities ranging from 75.2% to 99.1% compared with the radioimmunoassay. Of 211 sera which gave positive results with four or more of the tests, none was negative by the radioimmunoassay and Abbott EIA, three were negative in Cetus IHA and Enzygnost EIA, and 11 were negative in the modified complement fixation test. Virenz G and Cytomegalisa Stat EIAs, however, gave 40 (19%) and 49 (23.2%), respectively, as negative. The results confirmed the reliability of the radioimmunoassay for the detection of the antibody status to CMV, but this test is too elaborate for a screening procedure. The Abbott EIA and Cetus IHA were found to be the most suitable for this purpose in spite of high false positive rates.

A user's guide to the indirect solid-phase radioimmunoassay for the detection of cytomegalovirus-specific IgM antibodies

In this review full laboratory details are given of a solid-phase indirect radioimmunoassay for the detection of specific IgM antibodies against cytomegalovirus. Practical advice is given on readily available commercial sources of reagents, a simple iodination procedure, the rapid dilution of sera under test and calculation of the results with a computer program available from the authors. Problems encountered with the assay are also detailed such as interference by rheumatoid factor, deterioration of the radiolabel and high background binding found with some sera. If these problems are avoided by the methods given in the text then the radioimmunoassay has been shown to give results of 100% specificity with 89% sensitivity for detecting congenital infection and 92% sensitivity for identifying primary cytomegalovirus infection in pregnant women.

Improving the varicella-zoster virus: IgG radioimmunoassay procedure by the use of purified antigen

The indirect radioimmunoassay (RIA) for detecting and assaying IgG class antibodies against varicella-zoster virus (VZV) can be improved by simple purification of the viral antigen. This is achieved by reducing binding to cellular components present in crude antigens. The purified antigen is particularly useful for testing sera that either bind excessively to normal control antigen or give equivocal results when crude antigens are used.

Detection of IgM antibodies against cytomegalovirus: comparison of two radioimmunoassays, enzyme-linked immunosorbent assay and immunofluorescent antibody test

The sensitivity and specificity of direct antibody radioimmunoassay (RIA), M-antibody capture RIA (MACRIA), enzyme-linked immunosorbent assay (ELISA), and the immunofluorescent antibody (IFA) test for the detection of CMV-specific IgM was compared using 40 sera selected from different groups of patients. RIA, MACRIA, and ELISA gave concordant results with thirty-two sera but discordant results with eight sera, of which three were cord sera from congenitally infected babies, three were from immunocompromised patients with recurrent CMV infections, and two were from patients with lymphadenopathy and Paul-Bunnell-positive mononucleosis, respectively. RIA, MACRIA, and ELISA were of similar sensitivity with sera from adult patients, but ELISA was apparently less sensitive than RIA and MACRIA for the detection of CMV IgM in cord serum. By comparison IFA was significantly less sensitive than the other three tests. Rheumatoid factor is reactive in RIA, ELISA, and IFA but can efficiently be removed by absorption with latex-IgG beads or cross-linked human IgG.

Prenatal serological diagnosis of intrauterine cytomegalovirus infection

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Specific IgM class antibody production following infection with cytomegalovirus

Specific IgM class antibody production was studied in different groups of patients with characterized cytomegalovirus (CMV) infections using a radioimmunoassay (RIA). In pregnant women, IgM antibodies were detected only following primary infection and generally persisted less than 4 months. The demonstration of CMV-specific IgM during pregnancy is therefore diagnostic of recent primary CMV infection. In patients with symptomatic CMV infections, the appearance of IgM antibody was shown to be closely related to the onset of symptoms and coincided with production of complement fixing (CF) antibody. IgM antibodies were at maximum levels 3-4 weeks after presentation but generally declined to low or undetectable levels by 3-4 months. The significance of the results of testing for CMV-specific IgM in relation to clinical and other serological findings in these patients is discussed. IgM antibody production was also demonstrated in renal transplant patients with primary infections and in 6 of 21 recipients with secondary infections. In both groups the antibodies became detectable 3-6 weeks after transplantation but the titres were much higher following primary infection. IgM antibodies persisted throughout follow-up periods of up to 2 years after transplantation in some cases.

Comparison of radioimmunoassay and the gel filtration technique for routine diagnosis of rubella during pregnancy

Radioimmunoassay (RIA) for rubella-specific IgM antibodies was compared with haemagglutination-inhibition (HI) in conjunction with gel filtration for the diagnosis of rubella infection in pregnant women during a 1-year period. In total 476 women were investigated of whom 221 were tested for rubella IgM. Both techniques gave positive results with 64 sera, and RIA alone with one additional serum. Difficulties associated with the removal of non-specific HI activity were encountered with four sera all of which were negative by RIA. RIA was found to have practical advantages over the gel filtration method but is at present technically more difficult to perform.

The development and evaluation of a solid-phase radioimmunoassay (RIA) procedure for the determination of susceptibility to varicella

The development of a sensitive solid-phase radioimmunoassay (RIA) procedure for the detection of specific antibodies against varicella-zoster (VZV) is described. The test proved to be about 200 times more sensitive than complement fixation (CF) and far more efficient at detecting low levels of antibody in the sera of individuals with past history of varicella. It is suggested that this RIA-VZV test would be suitable for distinguishing between individuals who are either immune or susceptible to varicella, which could be useful in a variety of clinical situations but particularly in current and future evaluations of varicella vaccines.

Fetal infection resulting from maternal rubella after the first trimester of pregnancy

We have tried to measure the incidence of prenatal infection in 304 infants whose mothers had had rubella at various times after the first 12 weeks of pregnancy. Two methods of assessment were used: first, serum obtained soon after birth was tested for specific IgM antibody; secondly, serum obtained after the age of eight months was tested for specific IgG. When maternal rubella occurred 12-16 weeks after the last menstrual period specific IgM antibody was detected in 28 out of 50 infants (56%). The proportion fell progressively to 12% after maternal rubella at 24-28 weeks, rose to 19% after rubella at 28-36 weeks and then to 58% when the illness occurred during the last month of pregnancy. In all, IgM antibody was detected in 77 out of 260 infants (29%). The fetus can thus be infected at any time during the second and third trimesters of pregnancy, but the risk varies at different stages.The figures for the prevalence of IgG antibody were greater throughout, because some infants had IgG who had previously lacked specific IgM. After maternal rubella at 12-16 weeks IgG antibody persisted in 22 out of 31 infants (71%). The proportion fell to 28% after rubella at 24-28 weeks and then increased progressively to 94% after rubella during the last month. In all, IgG antibody persisted in 94 out of 190 infants (49%). The true rate of fetal infection probably lies between the rates estimated from the presence of IgM antibody and the subsequent prevalence of IgG.Infants whose mothers had rubella at any time during pregnancy should be examined regularly for possible evidence of damage.

Evaluation of a radioimmunoassay for IgM-class antibodies against cytomegalovirus

A solid-phase radioimmunoassay (RIA-IgM) test for cytomegalovirus (CMV)-specific IgM-class antibodies is described and its potential diagnostic usefulness in adult patients is evaluated. IgM-class antibodies were readily detected by RIA in early convalescent sera from patients with serologically confirmed primary CMV infection, as well as in sera from patients with CMV mononucleosis. Serum specimens obtained several months after primary infection gave either negative results of low antibody titres, indicating that the IgM response is transient in these patients. CMV-specific IgM was also detected in 7 of 10 patients with symptoms and supportive serological evidence suggestive of recent active CMV infection. Conversely, 12 patients who were thought not to have experienced recent primary CMV infection, but whose sera gave high complement-fixing (CF) antibody titres, and 14 of 15 renal transplant recipients with reactivated CMV gave negative results in the RIA-IgM test. The results indicate that detectable IgM antibody production is a constant feature in patients with primary infection but not in patients who experience mild secondary attacks. The RIA-IgM test is highly virus-specific and can reliably be performed with unfractionated serum, provided that false reactivity due to rheumatoid factor (RF) is excluded. Thus RIA is a simple and specific technique which could be usefully applied as a diagnostic tool in a clinical situation and in research.

Comparison of immunofluorescence and radioimmunoassay for detecting IgM antibody in infants with the congenital rubella syndrome

Immunofluorescence (IF) and radioimmunoassay (RIA) have been compared as methods for detecting IgM antibody in 124 infants with confirmed or suspected congenital rubella. IF was used to test sucrose density gradient fractions and RIA to test fractions and whole serum. When fractions were tested IF and RIA were equally specific and distinguished clearly between IgM and IgG, but RIA was the more sensitive method. The RIA titre in whole serum was always greater than in the peak IgM fraction and there was no evidence that testing the serum, rather than the fraction, could result in failure to detect IgM. With some sera RIA gave low titres which became negative after absorption with IgG-coated latex beads. The mechanism of this 'false positive' effect, which may have been due to IgM with anti-IgG activity, was not investigated, but if it can be removed by absorption it need not reduce the specificity of the test. During the first 6 months of life IgM antibody was detected by RIA in 30 out of 32 unfractionated sera and by IF in fractions from 28 of these. After the age of 6 months IgM was found progressively less frequently and the greater sensitivity of RIA became a more obvious advantage: 17 out of 60 specimens were positive by RIA and 11 of these were negative by IF. RIA testing of whole serum appears to be an economical, specific and sensitive method for detecting IgM antibody in congenital rubella, of particular value when the titre of antibody is low.

The detection of rubella-specific IgM antibodies by radioimmunoassay

An indirect solid-phase radioimmunoassay (RIA) has been developed for the detection of immunoglobulin (Ig) class-specific rubella antibodies. A commercial rubella haemagglutinin is dried and fixed on to the wells of flexible microtitre plates and allowed to react with serial dilutions of whole or fractionated human sera. Class-specific rubella antibodies are then detected by determining the specific binding of 125I-labelled anti-human IgG or IgM. The RIA was first evaluated by comparison with the haemagglutination-inhibition (HI) test for the detection of rubella-specific IgM in gel-filtration fractions. RIA was found to be as specific as HI but 10-150 times more sensitive. Rubella-specific IgG antibodies did not interfere in specific IgM determinations by RIA and therefore the latter technique was applied to unfractionated sera. The results obtained indicate that RIA on unfractionated sera is a practical, sensitive and specific technique which could provide a reliable method for the diagnosis of rubella. The rubella-specific IgM titres obtained by RIA were not increased by the removal of IgG by pretreatment of sera with Staphylococcal Protein A.