Dengue and Zika virus infections in children elicit cross-reactive protective and enhancing antibodies that persist long term.

Dengue virus serotypes 1 to 4 (DENV1­4) and Zika virus (ZIKV) are mosquito-borne flaviviruses that induce both virus-specific and broadly reactive antibodies. A first DENV infection is thought to induce antibodies that wane over 2 years to titers that can subsequently enhance severe dengue disease. Secondary DENV infection with a different serotype is thought to induce stable, cross-serotype protective antibodies. Low dengue disease incidence after the recent Zika pandemic led to the hypothesis that ZIKV infection is also transiently cross protective. We investigated antibody kinetics in 4189 children up to 11 years after one and multiple DENV and ZIKV infections in longitudinal cohorts in Nicaragua. We used a DENV inhibition enzyme-linked immunosorbent assay (iELISA), which measures antibodies associated with protection against dengue and Zika disease and with enhancement of dengue disease severity. Unexpectedly, we found that overall DENV iELISA titers stabilized by 8 months after primary DENV infection to a half-life longer than a human life and waned, although gradually, after secondary DENV infection. Similarly, DENV iELISA titers were stable or rose after primary ZIKV infection but declined in individuals with histories of DENV and ZIKV infection. In contrast, kinetics of anti-ZIKV antibodies after ZIKV infection were similar regardless of prior DENV immunity. We observed heterogeneity in DENV iELISA titer, suggesting that individual antibody titer set point, rather than waning, is important for future dengue disease risk. Together, these findings change our understanding of anti-flavivirus antibody kinetics and have implications for measuring vaccine efficacy and for predicting future dengue and Zika outbreaks.

Zika virus infection enhances future risk of severe dengue disease.

The Zika pandemic sparked intense interest in whether immune interactions among dengue virus serotypes 1 to 4 (DENV1 to -4) extend to the closely related Zika virus (ZIKV). We investigated prospective pediatric cohorts in Nicaragua that experienced sequential DENV1 to -3 (2004 to 2015), Zika (2016 to 2017), and DENV2 (2018 to 2020) epidemics. Risk of symptomatic DENV2 infection and severe disease was elevated by one prior ZIKV infection, one prior DENV infection, or one prior DENV infection followed by one ZIKV infection, compared with being flavivirus-naïve. By contrast, multiple prior DENV infections reduced dengue risk. Further, although high preexisting anti-DENV antibody titers protected against DENV1, DENV3, and ZIKV disease, intermediate titers induced by previous ZIKV or DENV infection enhanced future risk of DENV2 disease and severity, as well as DENV3 severity. The observation that prior ZIKV infection can modulate dengue disease severity like a DENV serotype poses challenges to development of dengue and Zika vaccines.

Separation efficiency of a vacuum gas lift for microalgae harvesting.

Low-energy and low-cost separation of microalgae from water is important to the economics of microalgae harvesting and processing. Flotation under vacuum using a vacuum gas lift for microalgae harvesting was investigated for different airflow rates, bubble sizes, salinities and harvest volumes. Harvesting efficiency (HE) and concentration factor (CF) of the vacuum gas lift increased by around 50% when the airflow rate was reduced from 20 to 10 L min(-1). Reduced bubble size multiplied HE and CF 10 times when specific microbubble diffusers were used or when the salinity of the water was increased from 0‰ to 40‰. The reduction in harvest volume from 100 to 1L increased the CF from 10 to 130. An optimized vacuum gas lift could allow partial microalgae harvesting using less than 0.2 kWh kg(-1) DW, thus reducing energy costs 10-100 times compared to complete harvesting processes, albeit at the expense of a less concentrated biomass harvest.

Utilidad de la radiación beta para prevenir recidivas en el postoperatorio del pterigión / Beta therapy utility for prevention of pterygium recurrence

Para el presente estudio se captaron 93 casos de pterigión en 44 pacientes que presentaban pterigión en ambos ojos, incluyendo a tres pacientes con pterigión doble (nasal y temporal en el mismo ojo). A todos se les realizó extirpación quirúrgica del pterigión con la técnica de esclera descuierta y enforma simultánea en ambos ojos. En uso solo de los ojos (seleccionado aleatoriamente), se aplicó radiación beta (2,700 rads). Se efectuó seguimiento mínimo de seis meses y máximo de ocho meses. Se eliminaron del estudio a 19 casos, quedando al final 74 ojos divididos en dos grupos: un grupo de 37 ojos que sí recibieron radiación, en el cual recidivaron el 18.92% (7 ojos); y no recidivaron el 81.08% (30 ojos). Y el otro grupo, también de 37 ojos que no se radiaron, observándose racidiva en el 29.73% (11 ojos), y el 70.27% (26 ojos) restantes no recidivaron. Estadísticamente no existe diferencia significativa (p>0.05).

Modificaciones de la curvatura corneal en el postoperatorio de pterigion / Modifications of the curvature corneal on pterygia postoperatory

Este estudio se realizó en 88 ojos que presentaban pterigión no recidivante y con invasión corneal de más de 1 mm. Preoperatoriamente se realizó queratometría y medición de la invasión corneal, se efectuó extirpación del pterigión con la técnica de esclera descubierta, y seis meses después se realizó nuevamente queratometría. Se eliminaron 32 ojos, quedando al final del estudio un grupo de 56 ojos en los que se encontraron los siguientes hallazgos: las córneas preoperatoriamente esféricas, en su mayoría (60%) presentaron postoperatoriamente astigmatismo contra la regla (P<0.05), y el astigmatismo preoperatorio con la regla disminuyó en 0.5 D (P<0.05); en ambos casos por aumento de la curvatura corneal en el meridiano horizontal. Los cambios del astigmatismo preoperatorio contra la regla no tuvieron significación estadística (P>0.05)