Blood as a potential vehicle for the cytomegaloviruses

Direct assessment of cytomegalovirus transfusion-transmitted risks after universal leukoreduction

BACKGROUND

Cytomegalovirus (CMV) transfusion-transmitted disease (TTD) remains a clinical concern. Universal leukoreduction has become one of the main strategies for the prevention of CMV-TTD. Through prospective clinical follow-up and testing of transfusion recipients (TRs), the risk for CMV-TTD was studied.

STUDY DESIGN AND METHODS

Transfused units were all leukoreduced and not prospectively screened for CMV. For TRs with negative baseline CMV testing results (CMV total antibody and DNA), all follow-up TR samples were tested for CMV total antibody and DNA, and retained linked donor serum samples were tested for CMV total antibody. In cases when CMV-TTD was suspected, donor sera were also tested for CMV DNA and selected TR samples were tested for CMV immunoglobulin M antibody. Evaluable transfusion was defined as a transfusion with TR sample(s) collected 14 to 180 days posttransfusion.

RESULTS

Forty-six TRs were negative for CMV at baseline. There were 1316 evaluable cellular blood transfusions to these TRs. Of 1316 evaluable cellular products, 460 (35%) were positive for CMV total antibody tested using linked donor samples. Three cases of probable CMV-TTD were found; however, there was no definitive proof from donor follow-up that they were transfusion associated.

CONCLUSION

Among all 46 baseline seronegative recipients and 1316 evaluable transfusions, the calculated overall CMV-TTD risk was up to 6.5% (95% confidence interval [CI], 1.0%-18.0%) in terms of TRs and up to 0.23% (95% CI, 0.06%-0.62%) in terms of non-CMV-screened leukoreduced cellular products. In summary, after universal leukoreduction, CMV-TTD, while uncommon, may still occur.

Primary cytomegalovirus infection following open heart surgery

Among 674 patients undergoing open heart surgery in 1981-82, 86 (13%) were cytomegalovirus (CMV) antibody-negative when tested by an enzyme-linked immunosorbent assay prior to operation. At follow-up, 54 (67%) of 80 patients restudied had seroconverted after the operation, and 35 of the 54 seroconvertants had been ill with fever and elevated liver enzymes. Among the latter 35 patients, 26 demonstrated a significant rise in CMV antibody titre, most often detected in the third week following the onset of illness. The older patients were more susceptible to illness and seroconversion, and there was a positive correlation between age and the number of blood units given. Thus, at least one third of the seronegative patients developed symptomatic CMV illness after open heart surgery. This is a much higher incidence than earlier reported.

New developments in cytomegalovirus prevention and management

The use of CMVIG, approved in 1990 for prophylactic administration in seronegative recipients of kidneys from seropositive donors, has been shown to be extremely effective in preventing the considerable morbidity and mortality associated with CMV disease. While the complex interactions between CMV and the immune system, including the effects of immunosuppressive therapy, are still under investigation, passive immunization with CMVIG offers a practical, safe, and cost-effective means of clinical intervention in renal transplant patients known to be at risk for CMV disease. Further clinical studies will need to explore the mechanisms of interaction of CMVIG with reactivation of latent infection and superinfection and with allograft dysfunction and antirejection therapy. Studies that evaluate the use of CMVIG in combination with other pharmacologic and immunologic interventions, both for prevention and treatment of CMV disease, will guide the use of the drug. CMVIG promises to be most helpful in reducing morbidity and mortality in transplant recipients and other particularly at-risk populations such as those who are immunosuppressed iatrogenically.

Transfusion-acquired cytomegalovirus infection in children in a hyperendemic area

Thirty-nine children without previous cytomegalovirus (CMV) infection received blood transfusion in the National Taiwan University Hospital. The overall transfusion-acquired CMV infection rate was 36% (14/39). Donor CMV seropositive rate was 70%. None of the nine children who had received seronegative blood became infected, in contrast to 14 of the 21 children (67%) who had received seropositive blood (P = 0.002). Another significant risk factor associated with CMV infection was the use of fresh blood: 13 of 15 (87%) with fresh seropositive blood were infected, in contrast to one of six (17%) with "old" seropositive blood (P = 0.01). Most of the fresh blood was used within 24 hours. This blood processing method was shown to account for the extremely high rate of CMV infection in those who had received fresh seropositive blood. The results indicated that the incidence of CMV infection can be reduced by avoiding the use of fresh blood, especially blood less than 24 hours old. For such a population in Taiwan with high prevalence of positive CMV antibody, this approach was more applicable than screening donor blood for CMV antibody.

Serological markers of hepatitis B virus and cytomegalovirus infections in Norwegians with coagulation factor defects

The prevalence of serological markers for present and past hepatitis B virus (HBV) infection and antibodies against cytomegalovirus (CMV) among Norwegians with coagulation factor defects was examined in serum samples collected before virus-inactivated coagulation concentrates came into use. Sera collected in 1985/86 from 324 of 377 (86%) registered persons with such defects were available. Three persons were chronic carriers of HBsAg. The prevalence of HBV antibodies was 28% compared with about 5% in the general population. The highest prevalence rate was found among patients with severe haemophilia A (44%) and in patients with haemophilia B (39%). The prevalence of anti-CMV antibodies was 75% which is similar to that found in the general Norwegian population.

Transfusion-transmitted cytomegalovirus infections: significance and control

Cytomegalovirus (CMV) is a herpes virus which can give rise to primary infections, reactivated infections, or reinfections in humans. Seroepidemiologic studies have shown CMV infection to be worldwide with the highest antibody prevalences detected in Third World countries; however, significant regional variations can be seen within a given country. Antibody prevalence varies directly with age and inversely according to socioeconomic status. Numerous prospective studies of blood transfusion recipients carried out since 1966 have shown marked differences in infection rates but relatively little associated disease. Infection rates were highest in seronegative recipients given large amounts of fresh blood. Recently published reports have shown substantially lower infection rates than earlier studies, a change likely to be due to the current practice of transfusing fewer units of older blood. CMV has not been found to play a significant role in the etiology of posttransfusion hepatitis. CMV infections have been found to be an important source of morbidity and mortality in immunocompromised patients. Several studies of transfused, premature infants have shown significant differences in infection rates and disease expression. Seronegative low-birth-weight infants receiving blood from seropositive donors are at greatest risk. Blood from CMV-seronegative donors substantially lowers the risk of infection. Receiving a kidney or heart from a CMV-seropositive donor appears to be a more salient risk factor than blood transfusion in renal and cardiac transplant patients who are also more likely to have symptomatic CMV infections. Leukocyte transfusions have been found to be a significant source of CMV infection and disease in bone marrow transplant patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of six methods for the detection of antibody to cytomegalovirus

Five commercial assays were compared to a standardized complement fixation (CF) test for the detection of antibody to cytomegalovirus. Two hundred and thirty serum specimens were analyzed. In addition, nine pairs of acute- and convalescent-phase sera were tested by two of the commercial assays. The assays were compared as to sensitivity, specificity, and positive and negative predictive value, as well as incidence of false-positive and -negative results. Samples which did not agree in all the assays were retested and tested with an indirect fluorescent-antibody assay. Of 228 specimens, 103 (45.2%) were positive by CF. Of the 230 samples, 2 (0.9%) were inconclusive by CF and readable in the other assays. Of the 230 specimens, 97 (42.2%) were positive by an enzyme immunoassay (EIA; Litton Bionetics), 100 (43.5%) were positive by a second EIA (Abbott Laboratories), 104 (45.2%) were positive by a third EIA (M. A. Bioproducts). One hundred and eight (47.0%) were positive by indirect hemagglutination (IHA; Cetus Corporation), and 110 (47.8%) were positive by latex agglutination (LA; Hynson, Westcott and Dunning). Sensitivity and specificity were similar with all the assays (93 to 100%). The greater numbers of positive results by IHA and LA were confirmed by repeat CF testing at less than 1:8 dilution, and by indirect fluorescent-antibody assay. Acute- and convalescent-phase serum pairs showed a significant rise in antibody titer when tested by anticomplement immunofluorescence, IHA, and LA. There was good agreement among the assays, with LA having the highest sensitivity.

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.

Transfusion-acquired cytomegalovirus infection in cardiac surgery patients

The incidence of transfusion-acquired primary cytomegalovirus (CMV) infection was studied in 483 cardiac surgery patients. Ninety-six patients (20%) were found to lack antibody to CMV [CMV Ab(-)] as measured by radioimmunoassay. Sixty-eight CMV Ab(-) were followed by viral culture and/or serology from eight weeks to one year after transfusion. Transfusion requirements in CMV Ab(-) patients were as follows: whole blood/packed red blood cells, mean 4.7 +/- 2.6 units; platelets (20 patients), 6.9 +/- 3.8 units; fresh frozen plasma (25 patients), mean 3.3 +/- 1.6 units. Forty-nine percent of 235 donor units tested had antibody to CMV. One donor unit (0.4%) had CMV-specific IgM. This was not associated with CMV infection in the recipient. One patient (1.5%) demonstrated evidence of seroconversion to CMV during the follow-up period. This is significantly less than reported in previously published studies (P less than .01). Serological methods used, the age of the transfused blood, the immune status of the transfusion recipient, and the administration of passive antibody in fresh frozen plasma are factors that may be responsible for the low incidence observed.

Immunity to human cytomegalovirus measured and compared by complement fixation, indirect fluorescent-antibody, indirect hemagglutination, and enzyme-linked immunosorbent assays

The complement fixation test is currently the test employed most frequently to determine the presence of antibody to human cytomegalovirus. Several other techniques have been adapted for this purpose. A comparison of cytomegalovirus antibody titers was made between the complement fixation test, a commercially available enzyme-linked immunosorbent assay, an indirect immunofluorescent technique, and a modified indirect hemagglutination test. Forty-three serum samples were tested for antibodies by each of the above procedures. The enzyme-linked immunosorbent, immunofluorescent, and indirect hemagglutination assays were in close agreement on all samples tested; the titers obtained with these methods were all equal to or greater than the complement fixation titer for 38 of the 41 samples (92.6%). Two samples were anticomplementary in the complement fixation test but gave readable results in the other tests. The complement fixation test was the least sensitive of the procedures examined. The commercial enzyme-linked immunosorbent assay system was the most practical method and offered the highest degree of sensitivity in detecting antibodies to cytomegalovirus.