No abstract

The T cell repertoire required to control acute and latent CMV infection in otherwise healthy individuals was examined using both functional analysis and a wide range of MHC I tetramers. Both frequency and function of CMV specific T cells varied considerably between subjects, however, within subjects values remained stable over time. In total 16 +/- 3.5 CMV specific T cells/mul blood was detected, with obvious immunodominance between different CMV epitopes. Most subjects with latent infection showed low CMV specific T cell activity, whereas a subgroup (1/3) of individuals was high in either frequency or function of their CMV specific T cells. Patients with acute infection displayed high initial, but rapidly decreasing, numbers of CMV specific cells. In conclusion, a majority of healthy individuals readily seem to control latent CMV infection, whereas a subpopulation (1/3) of individuals uses a large proportion of their CD8+ T cell repertoire to control the infection.

Congenital cytomegalovirus (CMV) infection is the most common congenital infection causing childhood morbidity. The pathogenetic mechanisms behind long-term sequelae are unclear, but long-standing viremia as a consequence of the inability to convert the virus to a latent state has been suggested to be involved. Whereas primary CMV infection in adults is typically rapidly controlled by the immune system, children have been shown to excrete virus for years. Here, we compare T cell responses in children with congenital CMV infection, children with postnatal CMV infection and adults with symptomatic primary CMV infection. The study groups included 24 children with congenital CMV infection, 19 children with postnatal CMV infection and eight adults with primary CMV infection. Among the infants with congenital CMV infection, 13 were symptomatic. T cell responses were determined by analysis of interferon gamma production after stimulation with CMV antigen. Our results show that whereas adults display high CMV-specific CD4 T cell responses in the initial phase of the infection, children younger than 2 years have low or undetectable responses that appear to increase with time. There were no differences between groups with regard to CD8 T cell function. In conclusion, inadequate CD 4 T cell function seems to be involved in the failure to get immune control of the CMV infection in children younger than 2 years of age with congenital as well as postnatal CMV infection.

Background During the Covid-19 pandemic, the protection of healthcare workers has been in focus throughout the world, but the availability and quality of personal protective equipment has at times and in some settings been suboptimal. Materials and methods A total of 8679 healthcare workers and healthcare support staff in the county of Uppsala, north of Stockholm, were included in this cross-sectional study. All subjects were analysed for IgG anti-SARS-CoV-2, and predictors for positive serostatus were analysed in a logistic regression model including demographic parameters and self-reported employment characteristics. Results Overall, 577 (6.6%) were classified as seropositive, with no statistically significant differences between healthcare workers and support staff. Among healthcare workers, age (OR 0.987 per year, 95% CI 0.980–0.995), time to sampling (OR 1.019 per day, 95% CI 1.004–1.035), and employment at an outpatient care unit (OR 0.620, 95% CI 0.487–0.788) were statistically significantly associated with risk of infection. Covid-19 specific units were not at particular risk, compared to other units with comparable characteristics and staff demography. Conclusion Our findings indicate that SARS-CoV-2 transmission is related to inpatient healthcare work, and illustrate the need for a high standard of basic hygiene routines in all inpatient care settings.

Monitoring the reduction of IFNgammaCD4 compared with baseline during the first months after transplantation could be considered in predicting risk for high-grade CMV DNAemia and in deciding strategic approaches for pre-emptive and prophylactic therapy.