Congenital Cytomegalovirus: a "Now" Problem-No Really, Now

Rationally designed Human Cytomegalovirus gB nanoparticle vaccine with improved immunogenicity

Human cytomegalovirus (HCMV) is the primary viral cause of congenital birth defects and causes significant morbidity and mortality in immune-suppressed transplant recipients. Despite considerable efforts in vaccine development, HCMV infection still represents an unmet clinical need. In recent phase II trials, a MF59-adjuvanted gB vaccine showed only modest efficacy in preventing infection. These findings might be attributed to low level of antibodies (Abs) with a neutralizing activity induced by this vaccine. Here, we analyzed the immunogenicity of each gB antigenic domain (AD) and demonstrated that domain I of gB (AD5) is the main target of HCMV neutralizing antibodies. Furthermore, we designed, characterized and evaluated immunogenic responses to two different nanoparticles displaying a trimeric AD5 antigen. We showed that mice immunization with nanoparticles induces sera neutralization titers up to 100-fold higher compared to those obtained with the gB extracellular domain (gBECD). Collectively, these results illustrate with a medically relevant example the advantages of using a general approach combining antigen discovery, protein engineering and scaffold presentation for modern development of subunit vaccines against complex pathogens.

Short- and long-term impact of vaccination against cytomegalovirus: a modeling study

BACKGROUND

Infection with cytomegalovirus (CMV) is highly prevalent worldwide and can cause severe disease in immunocompromised persons and congenitally infected infants. The disease burden caused by congenital CMV infection is high, especially in resource-limited countries. Vaccines are currently under development for various target groups.

METHODS

We evaluated the impact of vaccination strategies and hygiene intervention using transmission models. Model parameters were estimated from a cross-sectional serological population study (n=5179) and a retrospective birth cohort (n=31,484), providing information on the age- and sex-specific CMV prevalence and on the birth prevalence of congenital CMV (cCMV).

RESULTS

The analyses show that vertical transmission and infectious reactivation are the main drivers of transmission. Vaccination strategies aimed at reducing transmission from mother to child (vaccinating pregnant women or women of reproductive age) can yield substantial reductions of cCMV in 20 years (31.7-71.4% if 70% of women are effectively vaccinated). Alternatively, hygiene intervention aimed at preventing CMV infection and re-infection of women of reproductive age from young children is expected to reduce cCMV by less than 2%. The effects of large-scale vaccination on CMV prevalence can be substantial, owing to the moderate transmissibility of CMV at the population level. However, as CMV causes lifelong infection, the timescale on which reductions in CMV prevalence are expected is in the order of several decades. Elimination of CMV infection in the long run is only feasible for a vaccine with a long duration of protection and high vaccination coverage.

CONCLUSIONS

Vaccination is an effective intervention to reduce the birth prevalence of cCMV. Population-level reductions in CMV prevalence can only be achieved on a long timescale. Our results stress the value of vaccinating pregnant women and women of childbearing age and provide support for the development of CMV vaccines and early planning of vaccination scenarios and rollouts.

Cytomegalovirus (CMV) seroprevalence in the adult population of Germany

BACKGROUND

Infection with cytomegalovirus (CMV) remains asymptomatic in most immunocompetent hosts, but is the leading cause of congenital viral infection worldwide and can be life-threatening in immunocompromised individuals. We aimed to assess CMV seroprevalence in a nationally representative sample of adults in Germany and to identify sociodemographic factors associated with CMV seropositivity.

METHODS

Blood samples from 6552 participants (18-79 years) of the "German National Health Interview and Examination Survey 1998", a population-based sample of the adult population in Germany, were tested for the presence of CMV antibodies using an Ig-multiplex assay. Weighted seroprevalence was calculated and weighted binomial regression was used to identify factors associated with CMV seropositivity.

RESULTS

Overall CMV seroprevalence was 56.7% (95%CI: 54.8-58.7%), with a higher seroprevalence in women (62.3%) than in men (51.0%). Seroprevalence increased with age: from 31.8% to 63.7% in men and from 44.1% to 77.6% in women when comparing the 18-29 with the 70-79 year age-group, respectively. CMV seroprevalence in women of childbearing age (18-45 years) was 51.7%. Factors significantly associated with CMV seropositivity were age, country of birth, smoking status, education, living in northern Germany and number of household members. In addition, having attended child care was associated with seropositivity in men, and number of siblings and living in East Germany in women.

CONCLUSION

Our results indicate that half the women of childbearing age were susceptible for primary CMV infection during pregnancy. CMV screening during pregnancy and informing seronegative women about CMV risk reduction measures could prevent congenital CMV infections with its serious consequences.

Periconceptional CMV infection prevention in Portugal: population subgroup study in a tertiary perinatal care center

Currently in Portugal, universal screening of pregnant women for Cytomegalovirus (CMV) infection is not performed. However, it is recommended to screen all women attending preconception care. We aimed to assess women's attendance to preconception care and if their serologic status regarding CMV was known and/or investigated in that consultation. In this cross-sectional study, we interviewed 240 women admitted to the obstetrical ward of a hospital in the Metropolitan Area of Porto (Portugal) about their adherence to preconception care and collected data regarding their CMV serologic status and its investigation. We found that 71.3% of the women who attended preconception care were not screened for CMV infection. Among primigravida, the screening rate was only of 30.4% (upper limit of CI 95%: 44.8%). There were no statistically significant differences between the private and public sectors of healthcare. We observed attendance to preconception care is high (73.1%). For the population subgroup of the metropolitan area of Porto, attendance to preconception care is at least 66%, with a 95% confidence level. Portuguese guidelines stating a woman's serologic status regarding CMV should be investigated in preconception care are not properly implemented. This suggests guidelines should assure the screening of previously non-screened women during pregnancy.