Prevention of transfusion-transmitted cytomegalovirus: reactivation of the debate?

Human cytomegalovirus (HCMV) trends in Sri Lanka: insights from a hospital-based seroprevalence analysis

BACKGROUND

Human Cytomegalovirus (HCMV) spreads through direct contact with blood, and other body fluids such as urine, saliva and breast milk. It is transmitted sexually and can also be passed from a pregnant mother to fetus via the placenta. While often asymptomatic in healthy individuals, HCMV causes symptomatic infections in immunocompromised people and congenital infections in fetuses. It is a common global congenital infection and can lead to morbidity and occasional mortality in newborns. Latent HCMV may reactivate in immunosuppressed individuals. This study aimed to determine the age and gender specific seroprevalence of HCMV in selected populations in Sri Lanka.

METHODS

A total of 820 blood samples obtained from 820 participants of selected low and high-risk populations in Sri Lanka, namely; hospital inpatients (n = 200), antenatal women (n = 80), blood donors (n = 80), cancer patients (n = 200), Sexually Transmitted Disease (STD) clinic attendees (n = 160) and Chronic Kidney Disease (CKD) patients on haemodialysis (n = 100) were tested for IgG antibodies against HCMV by Enzyme Linked Immunosorbent Assay (ELISA). Statistical analysis was performed using IBM SPSS Statistics version 30 (IBM® Corporation, New York, USA).

RESULTS

Overall HCMV seroprevalence was found to be 94.9% (778/820), whereas in males it was 95.2% (395/415) and in females it was 94.6% (383/405) (p = 0.691). Seroprevalence of HCMV in hospital inpatients, antenatal women, blood donors, cancer patients, STD clinic attendees and CKD patients on haemodialysis were found to be 92.5% (185/200), 100% (80/80), 90% (72/80), 96% (192/200), 93.1% (149/160) and 100% (100/100) respectively. Overall seroprevalence of HCMV increases with age ranging from 94.3% (33/35) in 15-19 years age group to 98.8% (84/85) in ≥ 60 years age group.

CONCLUSIONS

Seroprevalence of HCMV in diverse low and high-risk populations of Sri Lanka was studied for the first time. HCMV seroprevalence is similar between genders (p > 0.05) and increases with age. Over 90% of individuals are infected with HCMV by age 15, indicating a high prevalence of primary infections from early childhood to adolescence. This study provides essential background information on HCMV infection and its impacts in diverse populations of Sri Lanka and aids in executing preventive and therapeutic measures in high-risk populations.

Transfusion-transmitted CMV infection - current knowledge and future perspectives

Transmission of human cytomegalovirus (CMV) via transfusion (TT-CMV) may still occur and remains a challenge in the treatment of immunocompromised CMV-seronegative patients, e.g. after stem cell transplantation, and for low birthweight infants. Measures to reduce the risk of TT-CMV have been evaluated in clinical studies, including leucocyte depletion of cellular blood products and/or the selection of CMV-IgG-negative donations. Studies in large blood donor cohorts indicate that donations from newly CMV-IgG-positive donors should bear the highest risk for transmitting CMV infections because they contain the highest levels of CMV-DNA, and early CMV antibodies cannot neutralise CMV. Based on this knowledge, rational strategies to reduce the residual risk of TT-CMV using leucoreduced blood products could be designed. However, there is a lack of evidence that CMV is still transmitted by transfusion of leucoreduced units. In low birthweight infants, most (if not all) CMV infections are caused by breast milk feeding or congenital transmission rather than by transfusion of leucoreduced blood products. For other patients at risk, no definitive data exist about the relative importance of alternative transmission routes of CMV compared to blood transfusion. As a result, only the conduction of well-designed studies addressing strategies to prevent TT-CMV and the thorough examination of presumed cases of TT-CMV will achieve guidance for the best transfusion regimen in patients at risk.

Determination of the Biological Form of Human Cytomegalovirus DNA in the Plasma of Solid-Organ Transplant Recipients

Background

Whether cytomegalovirus (CMV) DNA exists in plasma as virion-associated or free DNA is uncertain.

Methods

An assay combining DNase I digestion and CMV quantitative polymerase chain reaction (DNase-CMV-qPCR) was developed to differentiate free naked DNA from virion DNA. One hundred three frozen and 10 fresh CMV DNA-positive plasma samples from solid-organ transplant recipients (SOTRs) were tested. Three sets of paired qPCR (P-qPCR) assays with amplicons of variable length were used to study CMV DNA fragmentation in 20 SOTR plasma samples, viral stocks (Towne, Merlin, AD169) and the first World Health Organization (WHO) international standard (IS) for CMV DNA.

Results

In all plasma samples, 98.8%-100% of CMV DNA was free DNA; this was the only form in 93 of 103 (90.3%) frozen and all 10 fresh samples tested using DNase-CMV-qPCR. Low levels of virion CMV DNA were found in 10 of 103 (9.7%) samples with higher total DNA load. Cytomegalovirus DNA results were highly reproducible for 3 CMV virus stocks and WHO IS (P > .80), tested by three sets of paired q-PCR. However, for the 20 SOTR plasma samples, the smaller amplicon assay result was 2.6-fold, 3.4-fold, and 6.5-fold higher than the longer amplicion result (P < .001).

Conclusions

Cytomegalovirus DNA in SOTR plasma is almost exclusively free DNA, highly fragmented, and not virion associated.

Survey of Institutional Policies for Provision of "CMV-Safe" Blood in Ontario

OBJECTIVES

Debate continues on whether leukoreduction alone (LR) is sufficiently similar to leukoreduced cellular products drawn from cytomegalovirus (CMV)-seronegative (SN) donors to minimize the risk of transfusion-transmitted CMV (TT-CMV). We sought to determine the policy, inventory, and practice landscape of the province for TT-CMV mitigation.

METHODS

A web-based survey was distributed to hospitals in Ontario by Canadian Blood Services to collect data on their policies with respect to TT-CMV prevention.

RESULTS

TT-CMV mitigation practices varied by patient population, hospital size, and region. Smaller institutions remain committed to dual prevention, whereas academic hospitals favor a single-measure approach. Although smaller institutions attempt to align their policies with leadership sites, emulation is often inaccurate. The demands for SN products also appear to be significantly lower than the current screening practices of Canadian Blood Services.

CONCLUSIONS

Standardization is lacking on practices to prevent TT-CMV. Although there are barriers to harmonizing practices, the apparent shift to policies acknowledging LR as a sufficient protection is likely to continue.

Systematic Evaluation of Different Nucleic Acid Amplification Assays for Cytomegalovirus Detection: Feasibility of Blood Donor Screening

Acute primary cytomegalovirus (CMV) infections, which commonly occur asymptomatically among blood donors, represent a significant risk for serious morbidity in immunocompromised patients (a major group of transfusion recipients). We implemented a routine CMV pool screening procedure for plasma for the identification of CMV DNA-positive donors, and we evaluated the sensitivities and performance of different CMV DNA amplification systems. Minipools (MPs) of samples from 18,405 individual donors (54,451 donations) were screened for CMV DNA using the RealStar CMV PCR assay (Altona Diagnostic Technologies), with a minimum detection limit of 11.14 IU/ml. DNA was extracted with a high-volume protocol (4.8 ml, Chemagic Viral 5K kit; PerkinElmer) for blood donor pool screening (MP-nucleic acid testing [NAT]) and with the Nuclisens easyMAG system (0.5 ml; bioMérieux) for individual donation (ID)-NAT. In total, six CMV DNA-positive donors (0.03%) were identified by routine CMV screening, with DNA concentrations ranging from 4.35 × 10(2) to 4.30 × 10(3) IU/ml. Five donors already showed seroconversion and detectable IgA, IgM, and/or IgG antibody titers (IgA(+)/IgM(+)/IgG(-) or IgA(+)/IgM(+)/IgG(+)), and one donor showed no CMV-specific antibodies. Comparison of three commercial assays, i.e., the RealStar CMV PCR kit, the Sentosa SA CMV quantitative PCR kit (Vela Diagnostics), and the CMV R-gene PCR kit (bioMérieux), for MP-NAT and ID-NAT showed comparably good analytical sensitivities, ranging from 10.23 to 11.14 IU/ml (MP-NAT) or from 37.66 to 57.94 IU/ml (ID-NAT). The clinical relevance of transfusion-associated CMV infections requires further investigation, and the evaluated methods present powerful basic tools providing sensitive possibilities for viral testing. The application of CMV MP-NAT facilitated the identification of one donor with a window-phase donation during acute primary CMV infection.

Prevention of Transfusion-Transmitted Cytomegalovirus Infections: Which is the Optimal Strategy?

Traditionally, leukoreduction and selection of blood products from seronegative donors have been used as alternative strategies to reduce the risk of transfusion-transmitted cytomegalovirus infections (TT-CMV) in atrisk patients. After the introduction of universal leukoreduction for red blood cell and platelet concentrates in Germany, a controversy evolved as to whether the additional selection of blood products from seronegative donors would reduce or even increase the risk of TT-CMV. This review summarizes the current knowledge about CMV infections in blood donors and the implications of this information on the effect of potential transfusion strategies. Even though there are conflicting data about the incidence of TT-CMV remaining after the introduction of leukodepletion, it has been clearly shown that both prevalence and concentration of CMV DNA in peripheral blood are highest in newly seropositive donors. Therefore, avoidance of blood products from these donors is the most important goal of any transfusion strategy. This goal can be reached by: i) selection of blood products from seronegative donors, ii) provision of CMV DNA-negative blood products, or iii) provision of blood from long-term seropositive donors. In cases of suspected TT-CMV, all implicated donors should be investigated carefully to gather further knowledge on which donors confer the lowest risk for TT-CMV.

Cytomegalovirus (CMV) seroprevalence in Japanese blood donors and high detection frequency of CMV DNA in elderly donors

BACKGROUND

The current prevalence of cytomegalovirus (CMV) in Japan and the risk of CMV transfusion transmission are unknown in the era of seronegative leukoreduced blood components.

STUDY DESIGN AND METHODS

We measured CMV-specific immunoglobulin (Ig)M and IgG in 2400 samples of whole blood collected from 12 groups of blood donors categorized by sex and age at 10-year intervals from their teens to their 60s. We also tested for CMV DNA using polymerase chain reaction in the cellular fractions of all samples.

RESULTS

We found that 76.6% of blood donors were CMV seropositive. The seroprevalences among donors in their 20s and 30s were 58.3 and 73.3%, respectively. We detected CMV DNA in the cellular fraction of 4.3% of samples from donors in their 60s and in 1.0% of samples from donors younger than 60 years. None of the 562 seronegative samples was DNA positive. Furthermore, 14% of DNA-positive samples also contained DNA in the plasma fraction, and two of five such samples were derived from donors in their 60s. Leukoreduced plasma components derived from donations with CMV DNA in plasma samples also contained a relevant amount of CMV DNA.

CONCLUSION

The seroprevalence of CMV among Japanese blood donors of child-bearing age has not changed over the past 15 years. Latent CMV becomes reactivated more frequently among elderly donors than among younger donors. A proportion of them have free CMV DNA in their plasma fraction, which could not be diminished by leukoreduction. The risk of transfusion-transmitted CMV infection in blood with plasma CMV DNA should be determined.

The impact of donor cytomegalovirus DNA on transfusion strategies for at-risk patients

BACKGROUND

Cytomegalovirus (CMV) DNA is frequently detected in plasma of newly seropositive donors. Selection of leukoreduced blood products from donors with remote CMV infection could avoid transfusion-transmitted CMV infections (TT-CMV) due to primarily infected donors. However, there are no data about the prevalence of reactivations in long-term seropositive donors compared to the incidence of window period donations in seronegative donors. Therefore, the optimal transfusion strategy for at-risk patients is unclear.

STUDY DESIGN AND METHODS

Whole blood samples from 22,904 donations were tested for CMV DNA, and CMV DNA-positive donations were categorized as donations from 1) seronegative donors, 2) newly seropositive donors, and 3) long-term seropositive donors.

RESULTS

Twenty-one donors were reproducibly CMV DNA-positive (0.09%). Frequency of detection and concentration of CMV DNA in whole blood were comparable for seronegative and long-term seropositive donors. Nonreproducibly positive results for CMV DNA in whole blood were more frequent in long-term seropositive donors (0.16% vs. 0.01%, p<0.01). Only low concentrations of CMV DNA in plasma were detectable in two seronegative donors and one long-term seropositive donor. Highest concentrations of CMV DNA in both whole blood and plasma, however, were found in newly seropositive donors.

CONCLUSION

Prevalences of window period donations among seronegative donors and reactivations among long-term seropositive donors, as well as the CMV DNA concentration in whole blood and plasma samples from these donors, are comparable. Therefore, blood products from both groups could be used for patients at risk for TT-CMV, while those of newly seropositive donors seem to bear an increased risk.

Blood transfusion safety in Africa: a literature review of infectious disease and organizational challenges

Blood safety remains an important public health concern in Africa where lack of availability or provision of unsafe blood adversely impacts morbidity and mortality in the region. In recognition of this shortfall, the World Health Organization (WHO) established a goal of regional blood safety by 2012 through improved "organization and management, blood donor recruitment and collection, testing of donor blood as well as appropriate clinical use of blood" (Tagny et al: Transfusion. 2008;48:1256-1261; Tapko et al: Status of Blood Safety in the WHO African Region: Report of the 2006 Survey http://www.afro.who.int/en/divisions-a-programmes/dsd/health-technologies-a-laboratories.html. Brazzaville, Republic of Congo: WHO Regional Office for Africa; 2006). Although there has been substantial progress toward meeting these objectives, there are continued obstacles to both development and sustainability. In a setting where transfusion oversight is still being improved, transfusion-transmitted infections are of real concern. The high prevalence of some transfusion-transmissible agents such as hepatitis B virus and HIV in the general population means that some infected blood units escape detection by even well-performed laboratory testing, resulting in potential downstream transmission to patients. The spectrum of transfusion-transmitted infection include conventional as well as exotic pathogens, many of which are endemic to the region, thereby imparting ongoing challenges to recruitment and testing strategies.

Defining the risks for cytomegalovirus infection and disease after solid organ transplantation

Cytomegalovirus continues to be one of the most clinically significant infections after solid organ transplantation. Classic definitions of patients at high risk for infection and tissue-invasive disease are focused on recipient-donor serostatus, type of organ transplanted, and overall level of immunosuppression. However, recent trends in clinical practice call for a reevaluation of cytomegalovirus infection risks after solid organ transplantation. Indeed, whereas early-onset cytomegalovirus infection is usually controlled by antiviral prophylaxis with ganciclovir and derivatives, delayed- and late-onset cytomegalovirus infection can develop after the completion of a course of preventive therapy. In addition, indirect effects of cytomegalovirus infection may occur as a result of persistent low-level viremia. Suboptimal dosing of antiviral drugs due to specific drug toxicities may result in the development of ganciclovir-resistant cytomegalovirus disease. The relationship between organ allograft rejection and cytomegalovirus infection and disease has been recognized for some time. Transplantation of increasing numbers of extended-criteria donor organs increases the risk of delayed graft function and acute rejection, prompting the use of more intensive immunosuppression. In addition, the trend to spare long-term exposure to calcineurin inhibitors has contributed to a resurgence in the use of polyclonal T-cell induction immunosuppressive agents, which may reduce host anticytomegalovirus immunity. We discuss the current trends in solid organ transplantation that provide a foundation for defining risks for cytomegalovirus infection and disease, including identification of patients who would benefit from more aggressive cytomegalovirus monitoring and prevention strategies.

The natural course of primary cytomegalovirus infection in blood donors

BACKGROUND AND OBJECTIVES

As cytomegalovirus (CMV) DNA is frequently detectable in the plasma of recently infected sero-positive blood donors, information concerning primary CMV infection is important for the identification of possibly infectious donors.

MATERIALS AND METHODS

Monitoring of 17 982 donors for CMV antibodies and DNA in plasma identified 14 subjects with ongoing primary CMV infection. Thirteen donors were interrogated for possible sources of infection and CMV-related symptoms, and monitored for CMV antigens, CMV DNA in plasma, leucocytes and urine, course of IgG and IgM antibodies as well as markers of systemic infection and parameters of organ function.

RESULTS

CMV antigens and DNA were detectable in peripheral blood for up to 54 and 269 days respectively. Clearance of CMV DNA from blood correlated with clearance of IgM antibodies, development of IgG antibodies against the membrane glycoprotein gB and development of high avidity IgG antibodies. Eighty-five percent of subjects with primary CMV infection, but even 69% of matched controls reported possibly CMV-related symptoms. Sixty-two and 23%, respectively, had contact with possible sources of infection. One donor developed a febrile illness accompanied by increased levels of CMV DNA in peripheral blood 2 to 3 weeks after seroconversion. In other donors, neither markers of systemic infection nor parameters of organ function correlated with the course of CMV DNA and antigens.

CONCLUSION

Potentially infectious donors can be identified by measuring CMV DNA, IgM antibodies or avidity of IgG antibodies. Alternatively, blood products donated during the first year after seroconversion should not be used for immunocompromised patients.

Seroprevalence of HHV-8, CMV, and EBV among the general population in Ghana, West Africa

Background

Human herpesvirus 8 (HHV-8), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) are prevalent in Africa, but less common elsewhere and the modes of transmission are still subject to debate. Generally, they rarely cause disease in the immunocompetent host but are highly oncogenic when associated with immunosuppression. Although the high prevalence of HHV-8, CMV and EBV has been well documented in Africa, such data are sparse from Ghana.

Methods

Serum samples from 3275 HIV-seronegative healthy blood donors and 250 HIV-AIDS patients were tested for antibodies specific for HHV-8, CMV and EBV by IgG ELISA assays. Differences in seropositivity rates by gender and age were evaluated using the Chi-square test with Yates correction.

Results

Of the 3275 HIV-seronegative healthy blood donors tested, 2573 (78.6%) were males and 702 (21.4%) were females, with ages ranging from 18 to 65 years (median 32.6; mean 31.2; mode 30). Of the 250 HIV-AIDS patients tested, 140 (56%) were males and 110 (44%) were females, with ages ranging from 17 to 64 years (median 30.8; mean 30.3; mode 28). Among the HIV-seronegative healthy blood donors, overall seroprevalence of HHV-8, CMV and EBV was 23.7%, 77.6% and 20.0%, respectively. Among the HIV-AIDS patients, overall seroprevalence of HHV-8, CMV and EBV was 65.6%, 59.2% and 87.2%, respectively. The seroprevalence of HHV-8 (p < 0.005) and EBV (p < 0.001) was statistically significantly higher in HIV-AIDS patients compared to HIV-seronegative healthy blood donors. There was no statistically significant difference (p = 0.24) between CMV seroprevalence in HIV-AIDS patients and HIV-seronegative healthy blood donors. Age and gender were not independent determinants (p > 0.05) for all three infections among HIV-seronegative healthy blood donors and HIV-AIDS patients in Ghana.

Conclusion

The results presented herein indicate that HHV-8, CMV and EBV infections are hyperendemic in both HIV-seronegative and HIV-seropositive Ghanaians, and suggest primarily a horizontal route of transmission of these three viral infections in Ghana.