Specific IgM class antibody production following infection with cytomegalovirus

CMV proctitis: a rare disease presentation in a young and immunocompetent man

A young adult man presented to an outlying emergency department with a sore throat, fever and chills. Upon failure of symptomatic management and a course of amoxicillin, he developed rectal pain and loose stools. Despite outpatient doxycycline treatment for presumed chlamydial proctitis, he developed worsening rectal pain and bloody stools. Results on abdominal and pelvic CT were consistent with proctitis. His symptoms worsened despite added metronidazole for bacterial proctitis. Workup revealed an elevated erythrocyte sedimentation rate, C reactive protein and calprotectin, suggestive of a diagnosis of inflammatory bowel disease (IBD). A colonoscopy revealed proximal tightness of the rectum, and pathology reported features suggestive of IBD. He was treated with prednisone and mesalamine. However, immunostaining positive for cytomegalovirus (CMV) confirmed a diagnosis of tissue-invasive CMV proctitis. This was further supported by serological testing for CMV consistent with a diagnosis of CMV proctitis preceded by a primary CMV infection of the pharynx.

Prognosis of Human Cytomegalovirus in Cancer Patients Undergoing Chemotherapeutic Treatment in Egypt and an Emergent Prevalence of Glycoprotein B-5

The human cytomegalovirus (HCMV) is a global opportunistic β-herpes virus causing severe diseases in immune-compromised patients, such as malignant tumor patients, especially those undergoing chemotherapeutic treatment. This study aimed to determine the prevalence of HCMV-DNA in chemotherapeutic treatment naive cancer patients, and after chemotherapy, to compare between conventional nested PCR and ELISA techniques for the detection of HCMV, and to detect glycoprotein B genotypes. Plasma and serum samples before and after three chemotherapy cycles were collected from 49 chemotherapy-naive cancer patients. DNA was extracted from plasma samples using QIAamp® DNA Mini kit. HCMV-DNA was detected using a nested PCR technique. Multiplex nested PCR was used for HCMV-glycoprotein B (gB) genotyping. HCMV-IgG and -IgM were detected using ELISA technique. Thirty one (63.3 %) of the 49 plasma samples of the chemotherapy-naïve cancer patients were positive for HCMV-DNA; 21 of which remained positive after chemotherapy. However, 18 samples were negative of which 16 became positive after chemotherapy. gB-5 was the most common glycoprotein genotype detected (80.6 %), followed by gB-1, gB-3, gB-4, and gB-2. HCMV IgG was detected in the 49 serum samples of chemotherapy-naïve patients, and after exposure to chemotherapy. HCMV-DNA is commonly identified in cancer patients. Its detection after chemotherapy exposure may suggest HCMV reactivation. The most common genotype detected in cancer patients in Egypt is gB-5 in contrast to earlier research. IgG was detected in all patients. This indicates that HCMV is endemic in Egypt, necessitating the development of public awareness campaigns about HCMV infection and preventive strategies.

Evaluation of the indirect and IgM-capture anti-human cytomegalovirus IgM ELISA methods as confirmed by cytomegalovirus IgG avidity

Primary cytomegalovirus (CMV) infection during pregnancy often results in congenital CMV infection with severe clinical complications. IgM antibodies are one of the indices of primary infection. The IgG avidity index (AI) is also known to remain low for 3 months after primary infection. Here, we evaluated and compared the performance of CMV IgM and IgG avidity assays. Because sensitivity and specificity reportedly differ between CMV IgM kits, CMV IgM detection was compared between the two commercially available ELISA kits that are most commonly used in Japan. Sera for CMV IgM were first screened using a traditional indirect ELISA kit. Selected samples were then tested for CMV IgM and CMV AI using a CMV IgM-capture ELISA kit and a CMV IgG avidity assay, respectively. The rate of concordance between the IgM kits was 89% (42/47), indicating the absence of any significant difference. Most of the CMV IgM-positive plasma samples showed high CMV IgG AI; however, 18 commercially available plasma samples with low CMV IgG AI were all CMV IgM-positive. One plausible explanation for this discrepancy is that the duration of low IgG AI is shorter than that of IgM positivity. Alternatively, CMV IgM tests may generate pseudo-positive readouts in cases of congenital infection. Nevertheless, our study confirms that CMV IgG AI can be a reliable indicator of CMV primary infection.

EBV VCA IgM and cytomegalovirus IgM dual positivity is a false positive finding related to age and hepatic involvement of primary Epstein-Barr virus infection in children

Primary Epstein-Barr virus (EBV) infection is common in childhood, and dual positivity of serum EBV IgM and cytomegalovirus (CMV) IgM antibodies occur in some cases. This study aimed to evaluate the cause of EBV and CMV IgM dual positivity to determine whether it represents a false-positive finding or a true coinfection.A total of 494 children diagnosed with primary EBV infection, manifesting as infectious mononucleosis, were recruited. The diagnosis was based on positive EBV viral capsid antigen (VCA) IgM antibodies, and serum CMV IgM antibodies and liver enzymes were also evaluated in 149 subjects.Of 149 children with primary EBV infection, 40 (26.8%) had serum EBV VCA IgM and CMV IgM dual positivity. However, true CMV infection was confirmed only in 1 child of 40 (2.5%) who was positive for both serum CMV Ag and urine CMV polymerase chain reaction (PCR) and negative for serum CMV IgG antibody. Among the children with primary EBV infection, the rate of dual positivity was higher in infants and lower in adolescents (P = .013). Liver enzymes were more significantly elevated in children with dual positivity than in those with negative results for CMV IgM antibodies (P = .026), which correlated with the serum EBV and CMV IgM titers.Serum EBV and CMV IgM dual positivity are more prevalent in children with primary EBV infection than what was previously reported. Our results indicate that serum EBV and CMV IgM dual positivity represents a false-positive finding, as opposed to an actual CMV coinfection, possibly due to antigenic cross-reactivity.

Epstein-Barr virus and cytomegalovirus mononucleosis: Important causes of febrile illness in returned travellers

BACKGROUND

Diagnosing the cause of fever in the returned traveller is challenging. Efforts often focus on identifying 'exotic' pathogens. Primary Epstein-Barr virus (EBV) and cytomegalovirus (CMV) infections cause clinical features that overlap with many exotic pathogens. The age-matched seroprevalence of both EBV and CMV is greater in tropical than temperate areas. We describe the clinical and laboratory features of returned travellers diagnosed with primary CMV and EBV syndromes.

METHODS

Patients with laboratory-confirmed primary EBV and CMV infections who had attended the Hospital for Tropical Diseases (HTD), London between 1st October 2011 and 1st October 2016 were identified. Clinical and laboratory data were obtained and analysed.

RESULTS

Twenty-two patients with primary EBV infection and 31 with primary CMV infection were identified. The commonest presenting features of both infections were fever (81.1%), headache (50.9%) and arthralgia/myalgia (49.1%). Cervical lymphadenopathy was seen more frequently with EBV than with CMV (59.1% vs. 25.8%, P = 0.02). Transaminitis (79.2%) and lymphocytosis (52.8%) were the commonest laboratory abnormalities in both groups.

CONCLUSIONS

Primary EBV and CMV infections are important causes of febrile illness in returning travellers. Identification of these pathogens prevents unnecessary, expensive investigations for more 'exotic' pathogens and impacts clinical management for example facilitating prognostication and antimicrobial stewardship.

Clinical evaluation of new automated cytomegalovirus IgM and IgG assays for the Elecsys(®) analyser platform

Cytomegalovirus (CMV) is a leading cause of physical and neurological abnormalities in newborns. Hence, the diagnosis of CMV infection in pregnant women is necessary in order to allow appropriate management of their pregnancy. New assays have been developed for the Roche Elecsys® immunoassay platform that detect CMV-specific immunoglobulin (Ig)M and IgG, with the IgM assay designed to target IgM produced at the start of infection rather than IgM persisting later in infection. This study aimed to evaluate the performance of the new assays compared with other commercial kits widely distributed in laboratories. The performance of the Elecsys and comparator CMV IgM and IgG assays was assessed using 967 preselected patient samples characterised by CMV infection status, as well as being compared using 1,668 unselected clinical samples. The Elecsys CMV IgM and IgG assays performed consistently with comparator assays using the preselected samples. The Elecsys CMV IgM assay showed improved sensitivity compared with the Enzygnost® assay in primary infection (91.2 % vs. 79.4 %) and improved specificity over the Architect® assay in potentially cross-reacting samples (94.1 % vs. 82.4 %). The Elecsys IgM assay reported fewer positive results in the later stages of CMV infection compared with ETI-CYTOK-M ELISA, while the Elecsys IgG assay reported slightly fewer negative results in the early stages of infection compared with ETI-CYTOK-G ELISA. There was good agreement between Elecsys and comparator assays using unselected clinical samples (range 90.4-99.4 %). The Elecsys CMV IgM and IgG assays compare well with routinely used assays and are suitable for clinical use.

Primary human immunodeficiency virus infection presenting as elevated aminotransferases

BACKGROUND/PURPOSE

Primary human immunodeficiency virus type 1 (HIV-1) infection is often under-diagnosed because of its nonspecific presentations. Elevated aminotransferase levels is one of its clinical manifestations, but is infrequently reported in the literature. The objective of this study was to investigate cases of elevated aminotransferases as a manifestation of primary HIV-1 infection.

METHODS

A retrospective chart review from October 1990 to May 2009 of HIV-1 infected patients in a registered database at a tertiary hospital was conducted to identify patients diagnosed with primary HIV-1 infection. An elevated aminotransferase level was broadly defined as above-normal values of alanine or aspartate aminotransferases. Acute hepatitis markers were determined using stored serum samples.

RESULTS

Twenty-three of the 827 (2.8%) patients were identified as having a primary HIV-1 infection. All were male, with a median age of 26 years (range, 19-77 years), and the majority were men who had sex with men (19/23, 82.6%). The most common clinical manifestations were fever (95.7%), elevated aminotransferases (65.2%), fatigue (47.8%), and pharyngitis (47.8%). The median CD4 lymphocyte count was 374/μL (range, 109-674/μL) and the median log HIV viral load was 5.0 (range, 4.3-5.9). For the 15 patients with abnormal liver function tests, the median aspartate aminotransferase level was 112 U/L (range, 62-969 U/L) and the median alanine aminotransferase level was 146 U/L (range, 42-1,110 U/L).

CONCLUSION

Elevated aminotransferases may be an initial manifestation of primary HIV infection and is more common than expected. Primary HIV-1 infection should be one of the differential diagnoses considered in young men presenting with unexplained, new-onset liver function impairment.

Periconceptional cytomegalovirus infection: pregnancy outcome and rate of vertical transmission

OBJECTIVE

To evaluate pregnancy outcome and rate of vertical transmission in primary maternal periconceptional cytomegalovirus (CMV) infection.

METHODS

All women serologically diagnosed with primary periconceptional CMV infection between 1999 and 2008 were included. Periconceptional infection was defined as primary maternal CMV infection occurring within 4 weeks prior to the last reported menstrual period and up to 3 weeks following the expected date of the missed menstrual period. Intrauterine infection was verified by PCR and shell vial culture of amniotic fluid at 22-24 weeks or neonatal urine culture within 48 h of birth.

RESULTS

Of the 59 patients studied, 43 (73%) underwent diagnostic amniocentesis. Eleven of the 43 patients (25.5%) were positive for CMV contamination. Ten of the 11 patients (90%) elected to terminate pregnancy. Twelve women (20.3%) declined amniocentesis: of these 2 elected to undergo a first-trimester termination of pregnancy and 10 gave birth to a live-born infant. Six of the ten neonates were negative for CMV and two tested positive for urinary CMV; all eight were healthy on long-term follow-up, and two were lost to follow-up. The remaining four women had a spontaneous first-trimester abortion.

CONCLUSION

The risk of transmission of periconceptional CMV infection is lower than previously reported. These data should be borne in mind when counseling affected couples.

Cytomegalovirus (CMV) shedding is highly correlated with markers of immunosuppression in CMV-seropositive women

Cytomegalovirus (CMV) enters latency following primary infection and can subsequently reactivate. Reinfection with a different viral strain can also occur. During these events, CMV is shed in bodily fluids. This study examined correlates of CMV shedding in specimens obtained from the HIV Epidemiology Research Study, a multicenter cohort study of US women with or at high risk for human immunodeficiency virus (HIV) infection. Among the women studied, 91.4 % (911/997) were CMV IgG seropositive. Of these women, 2.7 % (25/911) were CMV IgM seropositive. CMV DNA was detected via real-time PCR more frequently in cervicovaginal lavage (CVL) specimens (55/764, 7.2 %) than in peripheral blood mononuclear cells (PBMCs) (26/897, 2.9 %). CMV viral loads in 1 ml CVL (median 534; mean 2598; range = 40-74, 844) were higher than in 10⁶ PBMCs (median 264; mean 1287; range = 35-13 ,250). CMV DNA in PBMCs was associated with HIV seropositivity [odds ratio (OR) 13.5; 95 % confidence interval (CI) 1.8-100], increasing HIV viral load (P<0.001 for trend), decreasing CD4 cell counts (P<0.001 for trend) and CMV DNA in CVL (OR 26; 95 % CI 10.7-64). CMV DNA in CVL specimens was associated with CMV IgM seropositivity (OR 4.3; 95 % CI 1.5-12.3), HIV seropositivity (OR 7.3; 95 % CI 2.6-20), increasing HIV viral load (P<0.001 for trend) and decreasing CD4 cell counts (P<0.001 for trend). The positive predictive value of CMV IgM seropositivity for CMV DNA shedding in either PBMCs or CVL was 20 %. In summary, CMV shedding in CVL and PBMCs was highly correlated with each other and with markers of immune suppression.

PCR detection of viral DNA in serum as an ancillary analysis for the diagnosis of acute mononucleosis-like syndrome due to human cytomegalovirus (HCMV) in immunocompetent patients

BACKGROUND

Serologic tests are occasionally inconclusive for the diagnosis of mononucleosis-like syndrome due to human cytomegalovirus (HCMV).

OBJECTIVES

To determine the value of viral DNA detection in serum by PCR as an ancillary test for the diagnosis of HCMV mononucleosis.

STUDY DESIGN

Sera from 34 previously healthy individuals with HCMV mononucleosis, obtained within 1 month after the onset of symptoms, were assayed for viral DNA by three commercial PCRs (QCA gB, QCA MIE and Amplicor CMV Monitor). Sera from 30 patients with evidence of past HCMV infection served as controls.

RESULTS

Viral DNA was detected in 20% of the samples from patients with HCMV mononucleosis by both QCA procedures, but in none of the controls. All samples tested negative by the Amplicor CMV Monitor.

CONCLUSION

Analysis of sera for the presence of HCMV DNA is of limited value for the diagnosis of HCMV mononucleosis.

Evaluation of an in-house specific immunoglobulin G (IgG) avidity ELISA for distinguishing recent primary from long-term human cytomegalovirus (HCMV) infection

This article describes the standardization and evaluation of an in-house specific IgG avidity ELISA for distinguishing recent primary from long-term human cytomegalovirus (HCMV) infection. The test was standardized with the commercial kit ETI-CYTOK G Plus (Sorin Biomedica, Italy) using 8 M urea in phosphate-buffered saline to dissociate low-avidity antibodies after the antigen-antibody interaction. The performance of the in-house assay was compared to that of the commercial automated VIDAS CMV IgG avidity test (bioM rieux, France). Forty-nine sera, 24 from patients with a recent primary HCMV infection and 25 from patients with a long-term HCMV infection and a sustained persistence of specific IgM antibodies, were tested. Similar results were obtained with the two avidity methods. All 24 sera from patients with recently acquired infection had avidity indices compatible with acute HCMV infection by the VIDAS method, whereas with the in-house method, one serum sample had an equivocal result. In the 25 sera from patients with long-term infection, identical results were obtained with the two methods, with only one serum sample having an incompatible value. These findings suggest that our in-house avidity test could be a potentially useful tool for the immunodiagnosis of HCMV infection.

Evaluation of a cytomegalovirus glycoprotein B recombinant enzyme immunoassay to discriminate between a recent and a past infection

Fetal damage following cytomegalovirus (CMV) intrauterine infection is mostly linked to primary infection. To differentiate primary infection from nonprimary infection, immunoglobulin M (IgM) tests are not reliable enough, and measurement of the IgG avidity appears to be the method that is the most widely used at present. In the present study the performance of the Vidas (bioMérieux) avidity assay was compared with that of a new enzyme immunoassay based on the use of a recombinant CMV glycoprotein B protein (Biotest).

Comparison between antigenemia and a quantitative-competitive polymerase chain reaction for the diagnosis of cytomegalovirus infection after heart transplantation

BACKGROUND

Antigenemia and quantitative polymerase chain reaction (PCR) are widely used for cytomegalovirus (CMV) diagnosis after heart transplantation due to their enhanced predictive values for disease detection when specific cut-off values are used. The purpose of this study was to compare, in the same patient setting, the predictive values of quantitative PCR and antigenemia for CMV disease detection, using specific cut-off values.

METHODS

Thirty heart transplant receptors were ch prospectively monitored for active CMV infection and disease detection, using quantitative PCR and anti- po genemia. Positive and negative predictive values for pr CMV disease detection were calculated using cut-off pr values for both antigenemia (5 and 10 positive cells/300,000 neutrophils) and quantitative-PCR (50,000 and 100,000 copies/10(6) leukocytes).

RESULTS

Active CMV infection was diagnosed in 93.3% of patients and CMV disease in 23.3%. The positive and negative predictive (%) values for CMV disease detection were 35/100 and 46.7/100, respectively, for quantitative PCR and antigenemia. Using 5 and 10 positive cells/300,000 neutrophils as cut-off values for antigenemia, the positive and negative predictive values (%) for disease detection were respectively 63.6/100 and 70/100. For quantitative PCR, the positive and th negative predictive values (%) for cut-off values of to 50,000 and 100,000 copies/10(6) leukocytes were 53.8/100 and 60/94.1, respectively.

CONCLUSION

In our series, antigenemia and quantitative-PCR had enhanced and similar predictive values for CMV disease detection when specific cut-off values were used. The choice between these two methods for disease detection may rely less on their efficiency and more on the experience and familiarity with them.

Predictive value of maternal-IgG avidity for congenital human cytomegalovirus infection

BACKGROUND

Human cytomegalovirus (HCMV) is now the most common cause of viral intrauterine infection. Fetal damage is mostly linked to maternal primary infection. It is therefore important to differentiate primary from recurrent or persistent HCMV infection in pregnant females. For this purpose, IgM tests are not reliable enough and the measurement of the IgG avidity appears to be presently the best method.

OBJECTIVE

To evaluate the performance of the measurement of HCMV-IgG avidity by a 8 M urea denaturation assay in predicting congenital infection in the offspring.

STUDY DESIGN

Seventy-eight women were included in this study on the basis of a HCMV IgM positive or equivocal result on a first serum during pregnancy, but without a documented seroconversion history. The IgG avidity was measured and correlated with the outcome of the pregnancy.

RESULTS

In eight cases of HCMV in utero infection the maternal HCMV-IgG avidity index was below 50%. One case of HCMV in utero infection was observed despite a high avidity index during the second trimester of the pregnancy. High or intermediate HCMV-IgG avidity indexes during the first trimester of pregnancy were not associated with a congenital infection.

CONCLUSIONS

Even in the presence of an IgM positive result, an HCMV IgG avidity index above 65% on a serum obtained during the first trimester of pregnancy could reasonably be considered as a good indicator of past HCMV infection. In these conditions invasive prenatal diagnosis is not necessary.

Avidity of IgG antibodies distinguishes primary from non-primary cytomegalovirus infection in pregnant women

BACKGROUND

Human cytomegalovirus (HCMV) is the most common cause of viral intrauterine infection. Fetal damage is mostly linked to maternal primary infection. It is therefore important to differentiate primary from non-primary infection in pregnant females. IgM tests often used for this purpose are not reliable enough.

OBJECTIVE

To evaluate an HCMV-IgG urea-elution assay for its ability to distinguish primary from non-primary infection. In this assay, soaking the antigen-antibody complex with an urea containing solution frees antibodies with low avidity but has no influence on those with high avidity. An avidity index (AI) was calculated: AI = (OD with urea/OD without urea) x 100.

STUDY DESIGN

HCMV-IgG avidity was measured on a single serum of 79 patients with past infection (pregnant women, graft recipients and blood donors) and of 63 patients (78 sera) with documented seroconversion (pregnant women and graft recipients). Sixty-one pregnant women positive or equivocal for HCMV-IgM but without a documented seroconversion were included in this study.

RESULTS

Most (72/79) of the patients with past infection had an AI > 65% and all but one had an AI > 50%. In pregnant women, in the case of a primary infection within the past 3 months, AI are usually (51/53) < 50% and never > 65%. Among the IgM positive pregnant women who lack a seroconversion history, 38 had AI > 65% suggestive of an infection that had occurred at least 3 months earlier, 11 had an AI in a grey area between 50 and 65% and 12 had an AI < 50%, suggestive of a recent primary infection.

CONCLUSIONS

In pregnant women, measurement of the IgG avidity may help to date a HCMV infection, an AI > 65% highly suggests a past infection while an AI < 50% corresponds to a recent primary infection.

Temporal patterns of immunoblot-reactive antibodies to cytomegalovirus in transplant recipients

A total of 234 sera from 44 allograft recipients were compared with 12 sera from 9 immunocompetent patients with symptomatic cytomegalovirus (CMV) infection and with 20 sera of 20 healthy individuals with latent CMV infection. The presence of immunoreactive proteins was not associated with a specific transplant group or with different immunosuppressive regimens but rather with the kinetics of the immune response. Acute phase sera demonstrated early antibodies to proteins p38 and p48, followed by high or still rising antibodies to high molecular weight proteins, particularly p150, and their later decline to persistent lower levels. Convalescent phase sera were identified serologically by the transient appearance of IgG antibodies directed to 22-26 kDa polypeptides. Immunoreactive p44 was present in 85% of all patients with mild disease and in 40% of all patients with severe CMV disease. When tested in parallel, the immunoblot analysis was shown to be a more sensitive indicator of early CMV antibodies in allograft recipients than the ELISA technique.

Symptomatic cytomegalovirus (CMV) infections identified by image cytometry and other parameters for CMV infection

Thirty-eight renal transplant recipients were followed during the first 3 months after transplantation. Once weekly, cultures of urine and buffy coat for cytomegalovirus (CMV) were taken and an immunocytochemical assay for immediate early antigens of CMV (IEA assay) was performed. Thirty patients had evidence of a CMV infection and 11 had a symptomatic CMV infection. All symptomatic patients had one or more positive urine cultures or a positive IEA assay. However, 15 patients with positive urine cultures and 12 patients with a positive IEA assay lacked any signs of symptomatic CMV disease. Moreover, 6 out of 15 patients with positive buffy coat cultures for CMV did not have symptomatic CMV disease. Using a computerized system to quantify IEA-positive granulocytes, we show that the absolute number of positive cells per million correlates very well with the occurrence of symptomatic CMV disease.

Immunoglobulin and hepatitis B surface antigen-specific circulating immune complexes in chronic hepatitis with hepatitis delta virus infection

IgM, IgG, and HBsAg containing circulating immune complexes (CIC) were determined, by conglutinin (K) and C1q assays, for assessing the role of CIC in hepatitis delta virus (HDV) infection in 54 HBsAg-negative controls and 85 HBsAg-positive patients with chronic hepatitis. The prevalence of HDV markers (HDV antigen and anti-HD) was 24.70% (21/85). CIC were a common feature of HDV infection with 95.24% of patients having at least one abnormal test result. The prevalence of elevated IgM-K, IgG-K, IgM-C1q, and IgG-C1q CIC were 85.71, 85.71, 57.14, and 85.71%, respectively. The prevalence of IgM class CIC were statistically higher in patients with HDV infection than in those without (P = .001 for the K assay and P = .023 for the C1q assay). There was no difference in the prevalence of IgG class CIC. Patients with HDV infection also have significantly higher median levels of IgM K-CIC (P = .002), IgG K-CIC (P = .049), and IgG C1q-CIC (P = .008). In patients with HDV infection, there was positive correlation between IgM C1q-CIC and transaminase levels (r = .519, P = .016 for AST; r = .500, P = .021 for ALT). There was no difference in the prevalence of HBsAg containing CIC between patients with HDV infection (76.19%) and those without (74.60%). In conclusion, IgM class CIC are the major CIC and correlate with disease activity in HDV infection. CIC may play a role in the pathogenesis of HDV infection.

Antibodies to cytomegalovirus in renal allograft recipients: correlation with isolation of virus

A cohort of 47 renal transplant recipients was studied prospectively for up to one year after transplantation. Cytomegalovirus (CMV) was isolated from 21 of the patients. The first time the virus was isolated seven patients were IgM positive, nine showed a significant rise in IgG titres, and 12 had a four-fold or greater rise in complement fixation titre. There was no significant difference in the time at which virus was first detected following transplantation between patients with primary CMV infection and those with reinfection or recurrent infection. In general, patients with primary infection shed virus consistently over long periods. Those with reinfection or recurrent infection shed virus intermittently or not at all. There were considerable differences between individual patients in the timing and pattern of the immune response. Taken overall, a four-fold rise detected by the complement fixation test correlated best with the onset of CMV shedding in primary infection. There was more variation in the pattern of antibody response in cases of reinfection or recurrent infection, with no single serological test correlating better than the others. It is concluded that serology is of limited value in the detection of active CMV infection after renal transplantation.

Low and high molecular weight cytomegalovirus-specific immunoglobulin M antibody in renal transplant patients with cytomegalovirus infections

Sera from 27 renal transplant patients with primary and recurrent CMV infections and which were known to contain CMV-specific IgM antibodies were investigated by indirect immunofluorescence for the presence of virus-specific high molecular weight IgM (19S IgM) and low molecular weight IgM (7S IgM). After sucrose gradient fractionation of the sera, 19S IgM was found in all 27 patients, whereas 7S IgM was present in 11 out of 19 (56%) patients with primary CMV infection and in 1 out of 8 (12%) patients with recurrent CMV infection. The presence of 7S IgM was unrelated to the titre of the virus-specific IgM in whole serum. The presence of IgM rheumatoid factor was monitored by a sensitive fluorescence assay using measles virus antigen/antibody complexes. The absorption of the serum fractions with heat-aggregated gamma globulin failed to remove the specific IgM staining indicating that it was not due to IgM rheumatoid factor. On the other hand adsorption with protein A/sepharose removed the specific IgM staining from the 7S IgM fractions but not from the 19S IgM fractions. This suggests that specific 19S and 7S IgM antibodies may belong to different subclasses of IgM.

Cytomegalovirus-specific antibody responses in renal transplant patients with primary and recurrent CMV infections

Cytomegalovirus (CMV) specific immunoglobulin G (IgG) and immunoglobulin M (IgM) antibody responses were measured before and after renal transplantation in 20 patients with primary CMV infection and in 16 patients with recurrent CMV infection. In primary CMV infection IgG antibody titres to late antigen (IgG-LA) measured by indirect fluorescence (IFA) were approximately seven times higher than those obtained by the complement fixation test (CFT). In contrast, in recurrent CMV infection this difference was found to be about twofold. Virus-specific IgM antibody to late antigen (IgM-LA) was detected in 100 percent of patients with primary CMV infection and in only 50 percent of patients with recurrent CMV infection. The IgM-LA titres were highest in primary CMV infection and reached peak levels at approximately 10 weeks post transplantation, whereas in recurrent CMV infection the IgM-LA titres were lower and reached peak levels at three months post transplantation. Moreover, IgM-LA was found to persist in patients from both groups at nine months post transplantation. IgM antibody to early antigen (IgM-EA) was not detected in any patient in this study. However, significant fourfold titre rises in IgG antibody to EA (IgG-EA) were detected in 100 percent of patients with recurrent CMV infection and in 50 percent of patients with primary CMV infection. These results clearly show the difference in antibody responses to the various antigens of CMV in patients with primary and recurrent CMV infection.

Cytomegalovirus infections in adult T-cell leukemia patients

Cytomegalovirus (CMV) infection frequently occurred in patients with malignant lymphoma of T-cell origin, especially with adult T-cell leukemia (ATL). This was evidenced by histopathological examination at autopsy, isolation of CMV, and detection of CMV antibodies that indicate recent or active infection. Cellular immune response was suppressed in most ATL patients when examined by skin hypersensitivity reaction to purified protein derivatives (PPD), streptococcal antigens (SuPs), and phytohaemoagglutinin (PHA). None of the CMV-positive patients reacted to them. Thus, the presence of tumor cells of T-cell origin and the absence of skin hypersensitivity reaction seem to be risk factors for CMV infection. Each CMV isolate exhibited unique DNA fingerprints, suggesting that cross-infection of CMV did not occur among the ATL patients on the same ward.

An enzyme labelled nuclear antigen immunoassay for detection of cytomegalovirus IgM antibodies in human serum: specific and non-specific reactions

A mu-capture enzyme linked immunosorbent assay was developed for detection of IgM antibody to cytomegalovirus (CMV). Virus-specific IgM was detected using horseradish peroxidase labelled nuclear CMV antigen (CMV-ELA). False-positive reactions caused by Paul-Bunnell-Davidsohn (PBD) positive sera and antinuclear antibody (ANA) positive sera were identified in a combination assay employing enzyme labelled nuclear control antigen (CO-ELA) in parallel to the CMV-ELA. Four of five PBD positive and 30 of 31 ANA positive sera reactive with the CMV-ELA were identified as false positive reactions in the combined ELA-assay. The reactivity in PBD-positive sera could not be explained by antigenic cross reactivity between CMV and Epstein-Barr virus, and the results further suggested that different cell specified components of the CMV-ELA were responsible for the reactivity of PBD-positive as compared to ANA-positive sera. One of 314 healthy blood donors, 12 of 12 patients with primary CMV infection, and 11 of 15 patients with secondary CMV infection had detectable CMV IgM antibodies. Comparison of different CMV-ELAs revealed that pronounced differences in specificity as well as sensitivity may exist.

Antibody isotype response after human cytomegalovirus infection

The antibody isotype response to human cytomegalovirus (CMV) was studied in paired sera from patients with primary and recurrent CMV infection. The majority of sera was obtained from immunocompromised patients. In the 48 patients with primary CMV infection, CMV-specific IgM (CMV-IgM) and IgG (CMV-IgG) antibodies were found in all patients, and CMV-specific IgA (CMV-IgA) and IgE (CMV-IgE) antibodies in 46 patients. CMV-IgM, -IgA, and -IgE antibodies were found in, respectively, 21, 31 and 4 of the 53 patients with recurrent CMV infection, and in, respectively, 3, 3 and 1 of the healthy controls. The results indicate that CMV-IgE is a better marker of primary CMV infection than CMV-IgM, and confirm that detection of CMV-IgM and -IgA may also be useful for diagnosis of recurrent CMV infection.

Molecular biology and immunology of cytomegalovirus

The application of modern biochemical techniques has led to a rapid improvement in our knowledge of the molecular biology of CMV. Several coding regions of the DNA genome have been identified with certainty and major virus-coded proteins have been given provisional names. The cascade expression of the CMV genome has been shown to be controlled by mechanisms similar to those found in other herpes viruses, together with novel post-transcriptional controls which remain to be defined. The control of CMV replication by the host involves both non-specific and specific defence mechanisms. The induction of natural killer cells and interferon early after CMV infection appears to be the most important aspects of the non-specific host defence against the virus. The cell-mediated immune response, in particular the generation of Tc cells against CMV early antigens, is probably the most important facet of the specific immune defence against CMV. When intact these defence mechanisms appear to be efficient in restricting viral replication; however, when such immunity is compromised, the balance rapidly swings in favour of the virus. As our understanding of the interaction between the host and the virus increases, it may be possible to redress the balance in such cases in favour of the host.

Immunoglobulin M to cytomegalovirus in primary and reactivation infections in renal transplant recipients

Two commercially available enzyme immunoassays and one assembled in house were used to measure immunoglobulin M (IgM) antibody to cytomegalovirus (CMV) in a total of 220 serum specimens from 104 renal transplant recipients. All assays included a step in which interfering IgG antibody was removed or complexed. Concordance of results between pairs of assays ranged from 84 to 96%. All sera from patients with recent seroconversion (primary CMV infection) had measurable anti-CMV IgM. Among those already seropositive to CMV when transplanted, 26 to 55% had IgM antibody posttransplant, depending on the assay. This was observed regardless of the CMV serologic status of the kidney donor, indicating that reactivation of endogenous CMV, as well as reinfection, can induce this antibody in transplant recipients. Four cadaver donors known to transmit CMV to eight recipients did not have measurable IgM antibody to CMV.

Serum antibodies to individual cytomegalovirus structural polypeptides in renal transplant recipients during viral infection

In a longitudinal study we examined by immunoblotting (IB) the development and the evolution of the humoral immune response against individual cytomegalovirus (CMV) structural polypeptides in a total of 80 serum samples from 13 renal transplant recipients showing serological evidence of CMV infection and five renal transplant recipients with an anti-CMV antibody level unchanged over the observation period. The results showed that the IB reactivity at the time of transplantation may be a good index of the host's humoral immune status against CMV; by using this procedure it is possible to identify a seroconversion by the detection of antibodies reacting with some intermediate molecular weight proteins in sera examined at high dilution. Furthermore, IB is a very sensitive procedure also for IgM detection as it anticipates the positivity of the enzyme immune assay for IgM.

Rapid diagnosis of cytomegalovirus infection

Several assays are in preparation for the diagnosis of cytomegalovirus infection in acquired immune deficiency syndrome and other immunocompromised patients. In particular, ELISA and DNA probes look to be particularly promising for testing body fluids and tissue sections respectively but these assays are not currently available. The technique of detection of early fluorescent antigen foci (DEAFF) has for some time been available as a diagnostic service to immunocompromised patients served by the author's laboratory. Although it requires cell culture and immunofluorescent techniques it is capable of detecting most patients with productive infection. In particular, the rapid availability of results has allowed patients to be entered into trials of new antiviral agents.

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.

Determination of specific cytomegalovirus IgM antibodies using infected air dried cells and isolated nuclei by immunoperoxidase assay

A simple immunoperoxidase assay (IPA), adapted for detection of serum IgM antibodies to cytomegalovirus (CMV) is described. The antigen consisted of CMV infected human embryonic fibroblasts or isolated nuclei. The sera were absorbed with aggregated gamma-globulins prior to testing. Rabbit anti-human IgM peroxidase conjugate was used to detect IgM bound to viral antigen. In parallel the enzyme linked immunosorbent assay (ELISA) technique was used to determine IgG and IgM antibodies to CMV, respectively. All patients with acute CMV infections who were tested had CMV-specific IgM antibodies by IPA, both whole cell and nuclei antigen. The maximal IgM titers were higher by ELISA than by IPA but in 3 of the CMV patients IgM was detected earlier by IPA (with both types of antigens) than by ELISA. In 3 of 5 transplant patients with recurrent CMV infection IgM was demonstrated by immunoperoxidase techniques, while by ELISA IgM was demonstrated in only 2 of them. No cross reactivity with other herpes viruses was observed. The described IPA is simple, rapid and has the potential for widespread use in routine laboratories.

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.

Measurement of BK papovavirus IgG and IgM by radioimmunoassay (RIA)

Current techniques for the measurement of BK papovavirus (BKV) specific IgM include sucrose density gradient centrifugation followed by hemagglutination inhibition (HAI) or indirect immunofluorescent (IF) staining of BKV infected cells using a fluorescein conjugated anti-human IgM antibody. These techniques are cumbersome and labor intensive and do not lend themselves to testing large numbers of sera. A solid phase radioimmunoassay (RIA) was developed to facilitate the measurement of BKV IgG and IgM in large numbers of sera. Solid phase antigen was prepared by adsorbing CsCl purified BKV antigen to polyvinyl chloride microtiter plates. Following reaction with serum, bound immunoglobulin was detected with iodinated goat anti-human IgG or IgM. RIA for the measurement of BKV IgG was sensitive with titers approaching 10(-6). Determination of IgG titers by RIA and HAI showed good agreement (P less than 0.01, correlation coefficient = 0.74). Measurement of BKV IgM was not affected by the presence of BKV IgG as evidenced by sucrose density gradient fractionation of IgM positive sera, removal of IgG by treatment with S. aureus protein A, and addition of BKV IgG to BKV IgM. Rheumatoid factor (RF) gave false positive IgM titers in the presence of BKV IgG when RF titers were greater than or equal to 1:640 by latex agglutination testing and BKV IgG levels exceed 1:256 by HAI. False positives due to RF could be eliminated by treatment of sera with sheep anti-human IgG antisera. RIA for BKV IgM was specific as sera containing JCV-, cytomegalovirus (CMV)-, rubella-, or hepatitis B core antibody (anti HBc)-IgM were negative by RIA. RIA detected BKV IgM in several sera from renal dialysis or allograft patients with titers ranging from 1:400 to 1:128,000 and demonstrated that BKV IgM persisted in sera of renal allograft patients for as long as 343 days post transplantation.

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.

The consequences of primary cytomegalovirus infection in pregnancy

Altogether 54 children exposed prenatally to maternal cytomegalovirus (CMV) infection were followed up in a prospective study. Nine had congenital infection with CMV and 37 escaped congenital infection; in 8 congenital CMV could not be confirmed. The birthweight of children with congenital CMV was significantly lower than that of both controls and those who escaped congenital infection. Intrauterine infection was not clinically suspected in any of the children with congenital CMV, although two had head circumferences less than the third centile. Subsequently one child with congenital CMV developed marked psychomotor retardation, and one, in whom congenital CMV was not confirmed, showed mild developmental delay. Speech and language ability was significantly impaired in children with congenital CMV compared with controls and those who escaped congenital infection, suggesting that subtle damage may have occurred. The incidence of intrauterine transmission of CMV after exposure to infection in the first trimester was 20% and in the third trimester 40%, but no congenital infections resulted from exposure in the second trimester. The severity of congenital infection was not related to the time of exposure in utero. Our findings suggest that the risk to an individual fetus from maternal infection in early gestation is so low that termination of pregnancy cannot be recommended; screening of women for primary CMV infection in pregnancy seems therefore to have limited value.