Rotavirus Vaccine Impact Within an Integrated Healthcare Delivery System in the United States

We assessed rotavirus vaccine impact using data on acute gastroenteritis (AGE) encounters within an integrated healthcare delivery system during 2000-2018. Following rotavirus vaccine introduction, all-cause AGE rates among children <5 years declined by 36% (95% confidence interval [CI]: 32%-40%) for outpatient and 54% (95% CI: 46%-60%) for inpatient encounters.

Rotavirus Vaccine Is Effective Against Rotavirus Gastroenteritis Resulting in Outpatient Care: Results From the Medically Attended Acute Gastroenteritis (MAAGE) Study

BACKGROUND

Rotavirus is a common cause of severe pediatric acute gastroenteritis. Two vaccines are licensed in the United States and have demonstrated high effectiveness against moderate to severe disease. However, fewer data are available on rotavirus vaccine effectiveness (VE) against milder disease.

METHODS

We leveraged active surveillance data from Kaiser Permanente Northwest to calculate rotavirus VE against medically attended rotavirus illness among age-eligible children. We utilized a test-negative case-control design and applied 4 distinct case definitions based on reverse transcription-quantitative real-time PCR (qRT-PCR) assay and enzyme immunoassay (EIA) test results. VE was calculated as 100 × (1 - odds ratio), and models were adjusted for age group.

RESULTS

The VE analysis population comprised 842 children, 799 (95%) of whom had mild disease requiring at most a clinic visit and 698 (83%) of whom were fully vaccinated against rotavirus. Age-adjusted VE was 70% (95% confidence interval [CI], 37-86%) against disease defined solely by qRT-PCR results, 72% (95% CI, 31-89%) against disease as defined by qRT-PCR with a quantification cycle (C q ) value <27, 73% (95% CI, 32-90%) against disease that was qRT-PCR positive but EIA negative, and 62% (95% CI, -20-88%) against disease defined solely by EIA. Results were similar when restricting to disease resulting in at most an ambulatory clinic or emergency department visit.

CONCLUSIONS

These results support the effectiveness of rotavirus vaccination in protecting US children from mild to moderate and severe disease. Our findings are also useful to show the effectiveness of rotavirus vaccination against qRT-PCR-defined illness.

Genetic diversity of human sapovirus across the Americas

BACKGROUND

Sapoviruses are responsible for sporadic and epidemic acute gastroenteritis worldwide. Sapovirus typing protocols have a success rate as low as 43% and relatively few complete sapovirus genome sequences are available to improve current typing protocols.

OBJECTIVE/STUDY DESIGN

To increase the number of complete sapovirus genomes to better understand the molecular epidemiology of human sapovirus and to improve the success rate of current sapovirus typing methods, we used deep metagenomics shotgun sequencing to obtain the complete genomes of 68 sapovirus samples from four different countries across the Americas (Guatemala, Nicaragua, Peru and the US).

RESULTS

VP1 genotyping showed that all sapovirus sequences could be grouped in the four established genogroups (GI (n = 13), GII (n = 30), GIV (n = 23), GV (n = 2)) that infect humans. They include the near-complete genome of a GI.6 virus and a recently reported novel GII.8 virus. Sequences of the complete RNA-dependent RNA polymerase gene could be grouped into three major genetic clusters or polymerase (P) types (GI.P, GII.P and GV.P) with all GIV viruses harboring a GII polymerase. One (GII.P-GII.4) of the new 68 sequences was a recombinant virus with the hotspot between the NS7 and VP1 regions.

CONCLUSIONS

Analyses of this expanded database of near-complete sapovirus sequences showed several mismatches in the genotyping primers, suggesting opportunities to revisit and update current sapovirus typing methods.

Specificity of regulatory CD4+CD25+ T cells for self-T cell receptor determinants

Although the phenotypic and regulatory properties of the CD4(+)CD25(+) T cell lineage (Treg cells) have been well described, the specificities remain largely unknown. We demonstrate here that the CD4(+)CD25(+) Treg population includes the recognition of a broad spectrum of human TCR CDR2 determinants found in the germline V gene repertoire as well as that of a clonotypic nongermline-encoded CDR3beta sequence present in a recombinant soluble T cell receptor (TCR) protein. Regulatory activity was demonstrated in T cell lines responsive to TCR but not in T cell lines responsive to control antigens. Inhibitory activity of TCR-reactive T cells required cell-cell contact and involved CTLA-4, GITR, IL-10, and IL-17. Thus, the T-T regulatory network includes Treg cells with specificity directed toward self-TCR determinants.

Functional assay for human CD4+CD25+ Treg cells reveals an age-dependent loss of suppressive activity

CD4+CD25+ regulatory T cells (Treg cells) prevent T cell-mediated autoimmune diseases in rodents. To develop a functional Treg assay for human blood cells, we used FACS- or bead-sorted CD4+CD25+ T cells from healthy donors to inhibit anti-CD3/CD28 activation of CD4+CD25- indicator T cells. The data clearly demonstrated classical Treg suppression of CD4+CD25- indicator cells by both CD4+CD25(+high) and CD4+CD25(+low) T cells obtained by FACS or magnetic bead sorting. Suppressive activity was found in either CD45RO- (naive) or CD45RO+ (memory) subpopulations, was independent of the TCR signal strength, required cell-cell contact, and was reversible by interleukin-2 (IL-2). Of general interest is that a wider sampling of 27 healthy donors revealed an age- but not gender-dependent loss of suppressive activity in the CD4+CD25+ population. The presence or absence of suppressive activity in CD4+CD25+ T cells from a given donor could be demonstrated consistently over time, and lack of suppression was not due to method of sorting, strength of signal, or sensitivity of indicator cells. Phenotypic markers did not differ on CD4+CD25+ T cells tested ex vivo from suppressive vs. nonsuppressive donors, although, upon activation in vitro, suppressive CD4+CD25+ T cells had significantly higher expression of both CTLA-4 and GITR than CD4+CD25- T cells from the same donors. Moreover, antibody neutralization of CTLA-4, GITR, IL-10, or IL-17 completely reversed Treg-induced suppression. Our results are highly consistent with those reported for murine Treg cells and are the first to demonstrate that suppressive activity of human CD4+CD25+ T cells declines with age.