Cytomegalovirus Infection in Ireland: Seroprevalence, HLA Class I Alleles, and Implications

A Rare Case of Elevated Transaminases With Incomplete Abortion Due to Cytomegalovirus Infection: An Experience From a Resource-Limited Setting

Cytomegalovirus (CMV) infection during pregnancy may cause spontaneous abortion, stillbirth, and death of newborns. CMV is the most common congenital infection in newborns. It generally has a benign course in immunocompetent individuals, while the severe disease is usually seen in immunocompromised patients. Most of the published studies about CMV infection describe congenital abnormalities in newborns. Only a handful of case reports mention CMV infection associated with elevated transaminases during pregnancy. Here, we present a case of incomplete abortion with elevated liver enzymes in a 26-year-old female caused by CMV infection. Our case report illustrates the importance of considering CMV infection as a differential in an incomplete abortion associated with elevated liver enzymes.

The impact of HLA polymorphism on herpesvirus infection and disease

Human Leukocyte Antigens (HLA) are cell surface molecules, central in coordinating innate and adaptive immune responses, that are targets of strong diversifying natural selection by pathogens. Of these pathogens, human herpesviruses have a uniquely ancient relationship with our species, where coevolution likely has reciprocating impact on HLA and viral genomic diversity. Consistent with this notion, genetic variation at multiple HLA loci is strongly associated with modulating immunity to herpesvirus infection. Here, we synthesize published genetic associations of HLA with herpesvirus infection and disease, both from case/control and genome-wide association studies. We analyze genetic associations across the eight human herpesviruses and identify HLA alleles that are associated with diverse herpesvirus-related phenotypes. We find that whereas most HLA genetic associations are virus- or disease-specific, HLA-A*01 and HLA-A*02 allotypes may be more generally associated with immune susceptibility and control, respectively, across multiple herpesviruses. Connecting genetic association data with functional corroboration, we discuss mechanisms by which diverse HLA and cognate receptor allotypes direct variable immune responses during herpesvirus infection and pathogenesis. Together, this review examines the complexity of HLA-herpesvirus interactions driven by differential T cell and Natural Killer cell immune responses.

Human herpesvirus diversity is altered in HLA class I binding peptides

Herpesviruses are ubiquitous, genetically diverse DNA viruses, with long-term presence in humans associated with infrequent but significant pathology. Human leukocyte antigen (HLA) class I presents intracellularly derived peptide fragments from infected tissue cells to CD8+ T and natural killer cells, thereby directing antiviral immunity. Allotypes of highly polymorphic HLA class I are distinguished by their peptide binding repertoires. Because this HLA class I variation is a major determinant of herpesvirus disease, we examined if sequence diversity of virus proteins reflects evasion of HLA presentation. Using population genomic data from Epstein–Barr virus (EBV), human cytomegalovirus (HCMV), and Varicella–Zoster virus, we tested whether diversity differed between the regions of herpesvirus proteins that can be recognized, or not, by HLA class I. Herpesviruses exhibit lytic and latent infection stages, with the latter better enabling immune evasion. Whereas HLA binding peptides of lytic proteins are conserved, we found that EBV and HCMV proteins expressed during latency have increased peptide sequence diversity. Similarly, latent, but not lytic, herpesvirus proteins have greater population structure in HLA binding than nonbinding peptides. Finally, we found patterns consistent with EBV adaption to the local HLA environment, with less efficient recognition of EBV isolates by high-frequency HLA class I allotypes. Here, the frequency of CD8+ T cell epitopes inversely correlated with the frequency of HLA class I recognition. Previous analyses have shown that pathogen-mediated natural selection maintains exceptional polymorphism in HLA residues that determine peptide recognition. Here, we show that HLA class I peptide recognition impacts diversity of globally widespread pathogens.

HLA-C*04:01 Affects HLA Class I Heterozygosity and Predicted Affinity to SARS-CoV-2 Peptides, and in Combination With Age and Sex of Armenian Patients Contributes to COVID-19 Severity

The novel SARS-CoV-2 coronavirus infection has become a global health concern, causing the COVID-19 pandemic. The disease symptoms and outcomes depend on the host immunity, in which the human leukocyte antigen (HLA) molecules play a distinct role. The HLA alleles have an inter-population variability, and understanding their link to the COVID-19 in an ethnically distinct population may contribute to personalized medicine. The present study aimed at detecting associations between common HLA alleles and COVID-19 susceptibility and severity in Armenians. In 299 COVID-19 patients (75 asymptomatic, 102 mild/moderate, 122 severe), the association between disease severity and classic HLA-I and II loci was examined. We found that the advanced age, male sex of patients, and sex and age interaction significantly contributed to the severity of the disease. We observed that an age-dependent effect of HLA-B*51:01 carriage [odds ratio (OR)=0.48 (0.28-0.80), Pbonf <0.036] is protective against severe COVID-19. Contrary, the HLA-C*04:01 allele, in a dose-dependent manner, was associated with a significant increase in the disease severity [OR (95% CI) =1.73 (1.20-2.49), Pbonf <0.021] and an advancing age (P<0.013). The link between HLA-C*04:01 and age was secondary to a stronger association between HLA-C*04:01 and disease severity. However, HLA-C*04:01 exerted a sex-dependent differential distribution between clinical subgroups [females: P<0.0012; males: P=0.48]. The comparison of HLA-C*04:01 frequency between subgroups and 2,781 Armenian controls revealed a significant incidence of HLA-C*04:01 deficiency in asymptomatic COVID-19. HLA-C*04:01 homozygous genotype in patients blueprinted a decrease in heterozygosity of HLA-B and HLA class-I loci. In HLA-C*04:01 carriers, these changes translated to the SARS-CoV-2 peptide presentation predicted inefficacy by HLA-C and HLA class-I molecules, simultaneously enhancing the appropriate HLA-B potency. In patients with clinical manifestation, due to the high prevalence of HLA-C*04:01, these effects provided a decrease of the HLA class-I heterozygosity and an ability to recognize SARS-CoV-2 peptides. Based on our observations, we developed a prediction model involving demographic variables and HLA-C*04:01 allele for the identification of potential cases with the risk of hospitalization (the area under the curve (AUC) = 86.2%) or severe COVID-19 (AUC =71%).

Sex-Associated Differences in Cytomegalovirus Prevention: Prophylactic Strategy is Potentially Associated With a Strong Kidney Function Impairment in Female Renal Transplant Patients

Post-transplantation cytomegalovirus (CMV) syndrome can be prevented using the antiviral drug (val)ganciclovir. (Val)ganciclovir is typically administered following a prophylactic or a pre-emptive strategy. The prophylactic strategy entails early universal administration, the pre-emptive strategy, early treatment in case of infection. However, it is not clear which strategy is superior with respect to transplantation outcome; sex-specific effects of these prevention strategies are not known. We have retrospectively analyzed 540 patients from the multi-centre Harmony study along eight pre-defined visits: 308 were treated according to a prophylactic, 232 according to a pre-emptive strategy. As expected, we observed an association of prophylactic strategy with lower incidence of CMV syndrome, delayed onset and lower viral loads compared to the pre-emptive strategy. However, in female patients, the prophylactic strategy was associated with a strong impairment of glomerular filtration rate one year post-transplant (difference: -11.8 ± 4.3 ml min-1·1.73 m-2, p = 0.006). Additionally, we observed a tendency of higher incidence of acute rejection and severe BK virus reactivation in the prophylactic strategy group. While the prophylactic strategy was more effective for preventing CMV syndrome, our results suggest for the first time that the prophylactic strategy might lead to inferior transplantation outcomes in female patients, providing evidence for a strong association with sex. Further randomized controlled studies are necessary to confirm this potential negative effect.

The effect of human leukocyte antigen A1 and B35-Cw4 on sustained BK polyomavirus DNAemia after renal transplantation

Human leukocyte antigen (HLA) class I presentation pathway plays a central role in natural killer (NK) cell and cytotoxic T-cell activities against BK polyomavirus (BKPyV) DNAemia. We determined the risk of sustained BKPyV DNAemia in 175 consecutive renal transplant recipients considering the simultaneous effect of donor/recipient HLA class I antigens and pre- or post-transplant variables. Median (IQR) age was 53 (44-64) years, and 37% of patients were female. 40 patients (22.9%) developed sustained BKPyV DNAemia [median (IQR) viral load: 9740 (4350-17 125) copies/ml]. In the Cox proportional hazard analysis, HLA-A1 (HR: 3.06, 95% CI: 1.51-6.17) and HLA-B35-Cw4 (HR: 4.63, 95% CI: 2.12-10.14) significantly increased the risk of sustained BKPyV DNAemia, while 2 HLA-C mismatches provided a marginally protective effect (HR: 0.32, 95% CI: 0.10-0.98). HLA-Cw4 is a ligand for NK cell inhibitory receptor, and HLA-B35 is in strong linkage disequilibrium with the HLA-Cw4 allele. The association between HLA-B35-Cw4 expression and sustained BKPyV DNAemia supports the important role of cytotoxic T cells and NK cells that would normally control BKPyV activation through engagement with immunoglobulin-like killer receptors (KIRs). Further studies are required to investigate the effect of HLA-C alleles along with NK cell activity against BKPyV DNAemia.

Using blood donors and solid organ transplant donors and recipients to estimate the seroprevalence of cytomegalovirus and Epstein-Barr virus in Canada: A cross-sectional study

BACKGROUND

Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections are common, causing significant morbidity in pregnancy (congenital CMV) and transplant recipients (CMV, EBV). Canadian prevalence data are needed to model disease burden and develop strategies for future vaccines. We estimated prevalence using screening data from blood donors and solid organ transplant (SOT) donors and recipients.

METHODS

We retrospectively analyzed CMV and EBV serology from Alberta SOT donors (n = 3,016) and recipients (n = 4,614) (1984-2013) and Canadian Blood Services blood donors (n = 1,253,350) (2005-2014), studying associations with age, sex, organ, year, and geographic region.

RESULTS

CMV seroprevalence rises gradually with age. By age 70, CMV seropositivity ranged from 67% (blood donors) to 73% (SOT recipients). Significant proportions of women of child-bearing age were CMV-seronegative (organ donors, 44%; SOT recipients, 43%; blood donors, 61%). Blood donor CMV seroprevalence decreased from 48% in Western Canada to 30% in Eastern Canada. Women were more likely to be CMV-seropositive (ORs = 1.58, 1.45, and 1.11 for organ donors, SOT recipients, and blood donors, respectively) and EBV-seropositive (ORs = 1.87 and 1.46 for organ donors and SOT recipients, respectively). EBV prevalence rises rapidly, and by age 17-29 years, 81% of SOT recipients and 90% of organ donors were seropositive.

CONCLUSIONS

Canada has relatively low and perhaps decreasing age-specific EBV and CMV prevalence, making Canadians vulnerable to primary infection-associated morbidity and suggesting benefit from future vaccines. Collection and analysis of routine serology screening data are useful for observing trends.

Role of Immunogenetics in the Outcome of HCMV Infection: Implications for Ageing

The outcome of host-virus interactions is determined by a number of factors, some related to the virus, others to the host, such as environmental factors and genetic factors. Therefore, different individuals vary in their relative susceptibility to infections. Human cytomegalovirus (HCMV) is an important pathogen from a clinical point of view, as it causes significant morbidity and mortality in immunosuppressed or immunosenescent individuals, such as the transplanted patients and the elderly, respectively. It is, therefore, important to understand the mechanisms of virus infection control. In this review, we discuss recent advances in the immunobiology of HCMV-host interactions, with particular emphasis on the immunogenetic aspects (human leukocyte antigens, HLA; killer cell immunoglobulin-like receptors, KIRs; immunoglobulin genetic markers, GM allotypes) to elucidate the mechanisms underlying the complex host-virus interaction that determine various outcomes of HCMV infection. The results, which show the role of humoral and cellular immunity in the control of infection by HCMV, would be valuable in directing efforts to reduce HCMV spurred health complications in the transplanted patients and in the elderly, including immunosenescence. In addition, concerning GM allotypes, it is intriguing that, in a Southern Italian population, alleles associated with the risk of developing HCMV symptomatic infection are negatively associated with longevity.

Seroprevalence of Cytomegalovirus among Women of Reproductive Age in Iran: A Systematic Review and Meta-Analysis

BACKGROUND

Human cytomegalovirus (CMV) able to cause infection for an entire lifetime. This systematic review and meta-analysis was conducted to determine seroprevalence of CMV among women of reproductive age in Iran.

METHODS

English and Persian databases such as Web of Science (WOS), PubMed, Scopus, Cochrane Library, SID, Iran doc, Iran Medex, Magiran, and Medlib were searched (from 2008 to 2017) accurately using the keywords: Cytomegalovirus, Pregnant women or Pregnancy, Epidemiology, Prevalence and Iran.

RESULTS

Results of 15 studies with total samples of 5253 persons from 2008 to 2017 were combined and meta-analyzed. The pooled prevalence rate of IgG among women was estimated 90% (95% CI: 87-93%). The highest prevalence rate of IgG was in Tehran, Rasht, Mashhad and Yasoj, all 100% (95% CI: 100-100%), and the lowest prevalence was in Jahrom 0.62% (95% CI: 53-71%). The overall prevalence rate of IgM among women was estimated at 0.06% (95% CI: 0.03-0.13%). The highest prevalence rate of IgM was in Kerman 0.34% (95% CI: 0.29-0.39%) and Mashhad 0.25% (95% CI: 0.2-0.31%), and the lowest prevalence was in Yasoj 0% (95% CI: 0.00%-0.00%).

CONCLUSION

The prevalence of immunity in Iran, is satisfactory. Nevertheless, to maintain and increase the level of immunity across the country, it is necessary to routinely screen the women of reproductive ages across the country.

Severe Symptomatic Primary CMV Infection in Inflammatory Bowel Disease Patients with Low Population Seroprevalence

Background

Cytomegalovirus disease in patients with inflammatory bowel disease is frequently the result of viral reactivation. Conversely, primary CMV infection is believed to be uncommon in immunocompetent adults due to high population seroprevalence.

Objectives

The aim of this study was to examine the frequency and severity of primary cytomegalovirus infection in an adult cohort of IBD patients.

Study Design

A retrospective review of a prospectively maintained database of 3200 IBD patients attending a single academic centre was performed. Patients with primary CMV infection 2010–13 were identified; clinical, serologic, and virologic parameters were studied in detail. The seroprevalence of CMV in the patient population was also evaluated.

Results

Eight patients with IBD (UC = 3, IBD-U = 1, CD = 4) presented with primary CMV infection. Patients presented with both gastrointestinal and extraintestinal symptoms. Mean age was 33 years, and median duration of disease was 72 months. All eight patients were receiving a thiopurine immunomodulator. Median duration of IM use was 144 weeks (range 7–720 weeks). All 8 patients required hospitalisation, with 1 ICU admission; the median length of hospital stay was 11 days (range 6–27). Infection resolved in all cases with withdrawal of immunomodulator and/or antiviral therapy. Seroprevalence of IgG to CMV, indicating prior exposure, in a subgroup of IBD patients (n = 80) was 30.5% and increased with age.

Conclusion

Primary cytomegalovirus infection can cause a severe illness in IBD patients, particularly those receiving immunosuppression. In areas where adult CMV seroprevalence is low, evidence of CMV should be sought in IBD patients presenting with any febrile systemic illness.

Seroprevalence of Cytomegalovirus Infection Among a Rural Population of Côte d'Ivoire

Human cytomegalovirus (HCMV) is a betaherpesvirus that can be pathogenic to humans. In particular, immunocompromised patients can develop life-threatening symptoms. In the present study, HCMV seroprevalence was investigated in a rural population of Western Côte d'Ivoire. Plasma samples collected from 166 apparently healthy subjects living in 8 villages surrounding the Taï Forest National Park were tested for anti-HCMV immunoglobulin G and M antibody with two commercial enzyme-linked immunosorbent assays. Prevalence of anti-HCMV IgG and IgM antibody was 100% and 5.4%, respectively. Anti-HCMV IgM positive was 10.2% (5/49) of the children and adolescents and 3.4% (4/117) of the adults. This observed decrease of IgM seropositivity and the seroprevalence difference between males and females (3.8% vs. 6.1%) was not statistically significant. In plasma of one IgM-positive participant, a low CMV load was detected indicating low-level replication. A second IgM-positive participant showed signs of local CMV replication. The other seven IgM-positive plasma samples likely reacted nonspecifically or due to polyclonal stimulation. Taken together, the results indicate that HCMV infection is hyperendemic in Côte d'Ivoire.

Erratum: Cytomegalovirus Infection in Ireland: Seroprevalence, HLA Class I Alleles, and Implications: Erratum

[This corrects the article DOI: 10.1097/MD.0000000000002735.].