Complement-dependent virion lysis mediated by dengue-Zika virus cross-reactive antibodies correlates with protection from severe dengue disease.

Primary infection with one of four dengue virus serotypes (DENV1-4) may generate antibodies that protect or enhance subsequent secondary heterotypic infections. However, the characteristics of heterotypic cross-reactive antibodies associated with protection from symptomatic infection and severe disease are not well-defined. We selected plasma samples collected before a secondary DENV heterotypic infection that was classified either as dengue fever (DF, n = 31) or dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS, n = 33) from our longstanding pediatric cohort in Nicaragua. We screened various antibody properties to determine the features correlated with protection from DHF/DSS. Protection was associated with high levels of binding of various antibody isotypes, IgG subclasses and effector functions, including antibody-dependent complement deposition, ADCD. Although the samples were derived from DENV-exposed, Zika virus (ZIKV)-naïve individuals, the protective ADCD association was stronger when assays were conducted with recombinant ZIKV antigens. Further, we showed that a complement-mediated virion lysis (virolysis) assay conducted with ZIKV virions was strongly associated with protection, a finding reproduced in an independent sample set collected prior to secondary heterotypic inapparent versus symptomatic DENV infection. Virolysis was the main antibody feature correlated with protection from DHF/DSS and severe symptoms, such as thrombocytopenia, hemorrhagic manifestations, and plasma leakage. Hence, anti-DENV antibodies that cross-react with ZIKV, target virion-associated epitopes, and mediate complement-dependent virolysis are correlated with protection from secondary symptomatic DENV infection and DHF/DSS. These findings may support the rational design and evaluation of dengue vaccines and development of therapeutics. One Sentence Summary: Complement-dependent virolysis mediated by a subset of ZIKV-cross-reactive antibodies protects from symptomatic DENV infection and severe disease.

Protection against symptomatic dengue infection by neutralizing antibodies varies by infection history and infecting serotype.

Dengue viruses (DENV1-4) are the most prevalent arboviruses in humans and a major public health concern. Understanding immune mechanisms that modulate DENV infection outcome is critical for vaccine development. Neutralizing antibodies (nAbs) are an essential component of the protective immune response, yet their measurement often relies on a single cellular substrate and partially mature virions, which does not capture the full breadth of neutralizing activity and may lead to biased estimations of nAb potency. Here, we analyze 125 samples collected after one or more DENV infections but prior to subsequent symptomatic or inapparent DENV1, DENV2, or DENV3 infections from a long-standing pediatric cohort study in Nicaragua. By assessing nAb responses using Vero cells with or without DC-SIGN and with mature or partially mature virions, we find that nAb potency and the protective NT50 cutoff are greatly influenced by cell substrate and virion maturation state. Additionally, the correlation between nAb titer and protection from disease depends on prior infection history and infecting serotype. Finally, we uncover variations in nAb composition that contribute to protection from symptomatic infection differently after primary and secondary prior infection. These findings have important implications for identifying antibody correlates of protection for vaccines and natural infections.

Natural infection by Zika virus but not DNA vaccination consistently elicits antibodies that compete with two potently neutralising monoclonal antibodies targeting distinct epitopes.

BACKGROUND: Autochthonous transmission of Zika virus (ZIKV) has been reported in 87 countries since 2015. Although most infections are mild, there is risk of Guillain-Barré syndrome and adverse pregnancy outcomes. Vaccines are urgently needed to prevent Zika, but sufficient understanding of humoral responses and tools to assess ZIKV-specific immunity are lacking. METHODS: We developed a blockade-of-binding (BOB) ELISA using A9E and G9E, two strongly neutralising ZIKV-specific monoclonal antibodies, which do not react with dengue virus. Receiver operating characteristic curve analysis assessed A9E and G9E BOB serodiagnostic performance. BOB was then applied to samples from a surveillance cohort in Risaralda, Colombia, and phase 1 ZIKV vaccine trial samples, comparing results against traditional serologic tests. FINDINGS: In the validation sample set (n = 120), A9E BOB has a sensitivity of 93.5% (95% CI: 79.3, 98.9) and specificity 97.8 (95% CI: 92.2, 99.6). G9E BOB had a sensitivity of 100% (95% CI: 89.0, 100.0) and specificity 100% (95% CI: 95.9, 100). Serum from natural infections consistently tested positive in these assays for up to one year, and reactivity tracks well with ZIKV infection status among sera from endemic areas with complicated flavivirus exposures. Interestingly, a leading ZIKV vaccine candidate elicited minimal BOB reactivity despite generating neutralising antibody responses. INTERPRETATION: In conclusion, A9E and G9E BOB assays are sensitive and specific assays for detecting antibodies elicited by recent or remote ZIKV infections. Given the additional ability of these BOB assays to detect immune responses that target different epitopes, further development of these assays is well justified for applications including flavivirus surveillance, translational vaccinology research and as potential serologic correlates of protective immunity against Zika. FUNDING: R21 AI129532 (PI: S. Becker-Dreps), CDCBAA 2017-N-18041 (PI: A. M. de Silva), Thrasher Fund (PI: M. H. Collins), K22 AI137306 (PI: M. H. Collins).

The association of neutralizing antibodies with protection against symptomatic dengue virus infection varies by serotype, prior infection history, and assay condition.

The four dengue virus serotypes (DENV1-4) are the most prevalent arboviruses in humans and a major public health concern worldwide. Understanding immune mechanisms that modulate DENV infection outcome is critical for epidemic preparedness and development of a safe and effective vaccine. Neutralizing antibodies (nAbs) are an essential component of the protective response, yet their measurement often relies on a single cellular substrate and partially mature virions, which do not capture the full breadth of neutralizing activity and may lead to biased estimations of nAb potency. Here, we investigated the characteristics of nAbs associated with protection against dengue cases using samples collected after one or more DENV infections but prior to subsequent symptomatic or inapparent DENV1, DENV2, or DENV3 infections from a long- standing pediatric cohort study in Nicaragua. By assessing nAb responses using Vero cells with or without the attachment factor DC-SIGN and with mature or partially mature virions, we found that nAb potency and the protective NT 50 cutoff were greatly influenced by cell substrate and virion maturation state. Additionally, the correlation between nAb titer and protection from disease depended on an individual's prior infection history and the subsequent infecting DENV serotype. Finally, we uncovered variations in nAbs composition that contributed to protection from symptomatic DENV infection differently after primary and secondary prior infection. These findings have important implications for identifying antibody correlates of protection in the context of vaccines and natural infections.

Haematological Alterations Associated with Selected Vector-Borne Infections and Exposure in Dogs from Pereira, Risaralda, Colombia.

Infections due to Ehrlichia, Anaplasma, Dirofilaria, Mycoplasma, Babesia and Hepatozoon continue to be highly prevalent in dogs, especially in tropical and subtropical areas, where vectors of many of them are present. However, many clinical aspects of dogs have not been characterized in detail, including assessing the haematological alterations associated with them, particularly in Colombia and Latin America. A group of 100 dogs with Ehrlichia, Anaplasma, Dirofilaria, Mycoplasma, Babesia and Hepatozoon infections/exposure were assessed by blood smear serology (SNAP4DX) and PCR in Pereira, Colombia. We performed blood counts to evaluate anaemia, leukopenia/leukocytosis, neutropenia, neutrophilia, lymphopenia/lymphocytosis, monocytosis, eosinophilia, and thrombocytopenia, among other alterations. Bivariate analyses were performed on Stata®14, with significant p < 0.05. From the total, 85% presented ≥1 infection (past or present), 66% with coinfections (≥2 pathogens) (Ehrlichia 75%), and 89% presented clinical alterations. A total of 100% showed anaemia, 70% thrombocytopenia, 61% monocytosis, and 47% neutropenia, among other alterations. Additionally, 11% presented pancytopenia and 59% bicytopenia. The median platelet count was lower in infected dogs (126,000 cells/µL) versus non-infected (221,000 cells/µL) (p = 0.003). Thrombocytopenia was higher among infected dogs (75%) versus non-infected (40%) (p = 0.006), with a 91% positive predictive value for infection. Median neutrophil count was lower in infected dogs (6591 cells/µL) versus non-infected (8804 cells/µL) (p = 0.013). Lymphocytosis occurred only among those infected (27%) (p = 0.022). Leukopenia was only observed among infected dogs (13%). Pancytopenia was only observed among infected dogs. Ehrlichiosis and other hematic infections have led to a significant burden of haematological alterations on infected dogs, including pancytopenia in a tenth of them, most with thrombocytopenia and all anemic.

Human monkeypox disease (MPX).

Monkeypox is a rare viral infection, endemic in many central and western African countries. The last international outbreak of monkeypox reported outside Africa occurred back in 2003. However, monkeypox has reemerged at a global scale with numerous confirmed cases across the globe in 2022. The rapid spread of cases through different countries has raised serious concerns among public health officials worldwide prompting accelerated investigations aimed to identify the origins and cause of the rapid expansion of cases. The current situation is reminiscent of the very early stages of the still ongoing COVID-19 pandemic. Overlapping features between these, two seemingly alike viral entities include the possibility for airborne transmission and the currently unexplained and rapid spread across borders. Early recognition of cases and timely intervention of potential transmission chains are necessary to contain further outbreaks. Measures should include rapid and accurate diagnosis of cases meeting case definitions, active surveillance efforts, and appropriate containment of confirmed cases. Governments and health policymakers must apply lessons learned from previous outbreaks and start taking active steps toward limiting the recent global spread of monkeypox. Herein, we discuss the status of the current monkeypox outbreaks worldwide, the epidemiological and public health situation at a global scale and what can be done to keep at bay its further expansion and future global implications.

Sensitive and Stable Molecular Detection of Dengue, Chikungunya, and Zika Viruses from Dried Blood Spots.

Standard molecular detection of many pathogens, in particular RNA viruses, requires appropriate handling in the field for preserving the quality of the sample until processing. This could be challenging in remote tropical areas. Dengue virus (DENV), chikungunya virus (CHIKV), and Zika virus (ZIKV) are RNA viruses, prominent among the causes of fever in the tropics. We aimed to test the stability of arboviral RNA in contrived dried blood spots prepared on Whatman 903 Protein saver cards as a means of sample collection and storage. We were able to detect DENV, CHIKV, and ZIKV by real-time RT-PCR up to 180 days after card inoculation with stable Ct values across the study period. Our study supports dried blood spots (DBS) on protein saver cards as a platform for stable detection of arboviral RNA of sufficient quality to be used in diagnostic RT-PCR assays and next generation sequencing.

Susceptibility to endemic Aedes-borne viruses among pregnant women in Risaralda, Colombia.

OBJECTIVES: Aedes-borne viruses (ABV) affect humans on every inhabited continent and frequently cause epidemics. Recent epidemics of chikungunya and Zika viruses (ZIKV) highlight that preparedness for future epidemics requires assessment of susceptibility, particularly among high-risk groups. We sought to determine immunity against the three major circulating ABV among pregnant women in an ABV-endemic area of Colombia. METHODS: A cross-sectional seroprevalence study was performed, enrolling women presenting to Labor and Delivery. Cord blood and maternal peripheral blood samples were obtained. IgG seroprevalence to flaviviruses and chikungunya was determined by ELISA. An abbreviated neutralization test was used to estimate the frequency and magnitude of immunity to Zika and four dengue serotypes. Cluster analyses explored epidemiologic factors associated with seroprevalence. RESULTS: Most women exhibited high levels of neutralizing antibodies to one or more ABV; however, nearly 20% were seronegative for flaviviruses. Our research took place after the epidemic peak of the ZIKV outbreak in Colombia in 2016. However, only 20% of pregnant women had high levels of Zika-neutralizing antibodies consistent with likely protective immunity to ZIKV. CONCLUSION: Hence, a high proportion of pregnant women in Risaralda remain susceptible to one or more ABV including the teratogenic ZIKV, indicating a risk for future epidemics in this region.

Seroprevalence canine survey for selected vector-borne pathogens and its relationship with poverty in metropolitan Pereira, Colombia, 2020.

Background: Tick-borne diseases (TBD) and dirofilariosis are currently not under surveillance in most Latin American countries. In addition, there is a significant lack of studies describing the current situation in most endemic areas, including Colombia. Therefore, seroprevalence studies are crucial for understanding the epidemiology of these vector-borne diseases. Methods: A serosurvey for TBD and dirofilariosis among 100 dogs was carried out in the municipality of Pereira, located in the Coffee-Triangle region, Colombia. Samples were tested using a rapid assay test system (SNAP® 4Dx®); based on an enzyme immunoassay technique' screening for antibodies to Anaplasma phagocytophilum/platys (sensitivity 99.1%)' Borrelia burgdorferi s.l. (98.8%), and Ehrlichia canis/ewingii (96.2%) by using specific antigens and checking for Dirofilaria immitis antigen based on specific antibodies (99.2%). Bivariate analyses were performed on Stata®14, significant p < 0.05. Findings: Global seroprevalence to the selected vector-borne pathogens was 74% (95%CI 65-83%). The highest seroprevalence was found for E. canis/ewingii (74%), followed by A. phagocytophilum/platys (16%). Seropositivity for Borrelia spp. and Dirofilaria spp. was 0%. All Anaplasma spp. seropositive dogs showed co-detection of Ehrlichia spp. (16%). Seroprevalence was significantly higher among dogs from families of lower socioeconomic status/level (I, 86%), followed by level II (74%), and III (36%) (p = 0.001). All dogs exhibiting anorexia (12%) were invariably seropositive (100%) (p = 0.029). Seroprevalence was higher among those showing mucocutaneous paleness (95%) compared to those without paleness (68%) (p = 0.013) (OR = 9.3; 95%CI 1.18-72.9). There was high variability in seroprevalence through the studied areas, ranging from 0% (La Libertad Park) up to Combia, Cesar Nader, Las Brisas and Saturno localities (100%) (p = 0.033). Interpretation: Given the high seroprevalence obtained in an area with documented ticks, there is a potential risk of zoonotic transmission to humans. Further seroprevalence studies in humans are needed to assess the prevalence of infections. Poverty is highly associated with these tick-borne pathogens in Pereira, as shown in the present study.

Application of SARS-CoV-2 Serology to Address Public Health Priorities.

Background: Antibodies against SARS-CoV-2 can be detected by various testing platforms, but a detailed understanding of assay performance is critical. Methods: We developed and validated a simple enzyme-linked immunosorbent assay (ELISA) to detect IgG binding to the receptor-binding domain (RBD) of SARS-CoV-2, which was then applied for surveillance. ELISA results were compared to a set of complimentary serologic assays using a large panel of clinical research samples. Results: The RBD ELISA exhibited robust performance in ROC curve analysis (AUC> 0.99; Se = 89%, Sp = 99.3%). Antibodies were detected in 23/353 (6.5%) healthcare workers, 6/9 RT-PCR-confirmed mild COVID-19 cases, and 0/30 non-COVID-19 cases from an ambulatory site. RBD ELISA showed a positive correlation with neutralizing activity (p = <0.0001, R2 = 0.26). Conclusions: We applied a validated SARS-CoV-2-specific IgG ELISA in multiple contexts and performed orthogonal testing on samples. This study demonstrates the utility of a simple serologic assay for detecting prior SARS-CoV-2 infection, particularly as a tool for efficiently testing large numbers of samples as in population surveillance. Our work also highlights that precise understanding of SARS-CoV-2 infection and immunity at the individual level, particularly with wide availability of vaccination, may be improved by orthogonal testing and/or more complex assays such as multiplex bead assays.

Should we concern about reinfection in COVID-19?: [Editorial] / ¿Deberíamos preocuparnos por la reinfección en COVID-19?: [Editorial]

After more than half year with the ongoing pandemic of the Coronavirus Disease 2019 (COVID-19) in all the continents, there are still many concerns regarding this emerging disease. The World Health Organization (WHO) declared COVID-19 as a pandemic in March 11, 2020, but it was on December 31, 2019, when a pneumonia of unknown cause was reported to WHO China Office. One of the most recent concerns about COVID-19 is the possibility of reinfection. Although experimental studies with animals suggested early in August 2020, that primary SARSCoV-2 exposure protects against subsequent reinfection in rhesus macaques, recent clinical case reports are showing that reinfection is possible.

Después de más de medio año con la pandemia en curso de la Enfermedad por Coronavirus 2019 (COVID-19) en todos los continentes, todavía hay muchas preocupaciones con respecto a esta enfermedad emergente. La Organización Mundial de la Salud (OMS) declaró la COVID-19 como pandemia el 11 de marzo de 2020, pero fue el 31 de diciembre de 2019, cuando una neumonía de causa desconocida fue notificada a la Oficina de la OMS en China. Una de las preocupaciones más recientes sobre COVID-19 es la posibilidad de reinfección. Aunque los estudios experimentales con animales sugirieron a principios de agosto de 2020, que la exposición primaria al SARSCoV-2 protege contra la reinfección posterior en macacos rhesus, los informes de casos clínicos recientes están mostrando que la reinfección es posible.

Physical Growth and Neurodevelopment of a Cohort of Children after 3.5 Years of Follow-up from Mothers with Zika Infection during Pregnancy-Third Report of the ZIKERNCOL Study.

INTRODUCTION: In utero Zika virus (ZIKV) exposure has been related to a group of congenital structural abnormalities called the congenital Zika syndrome, which also has been related to neurodevelopment alterations even in normocephalic children. Physical growth has been less explored, and delayed growth and malnutrition have been reported. OBJECTIVE: The objective of this study is to describe the growth and neurodevelopment features of normocephalic infants born from a cohort of mothers with RT-PCR confirmed ZIKV during pregnancy in Risaralda, Colombia. METHODS: We conducted a retrospective cohort, including normocephalic children born from mothers with RT-PCR confirmed ZIKV infection during pregnancy in Risaralda, Colombia. Physical growth was measured using WHO standards, and neurodevelopment was measured with the abbreviated neurodevelopment scale 2 validated for Colombia. RESULTS: After verifying inclusion and exclusion criteria, 16 children were followed during a median time of 28 months (IQR 23-31 months); for a total of 116 visits, 87.5% (n = 14) of the patients developed a growth alteration. Five presented post-natal microcephaly, and among them, four presented malnutrition or low height. Six patients developed macrocephaly. Patients with a normal head circumference had normal neurodevelopment. Only one patient with microcephaly persisted with impairment of the neurodevelopment at the end of follow-up. All the patients with macrocephaly had normal neurodevelopment. DISCUSSION: Our study suggests that growth could be altered in infants with in utero Zika exposure. We found a high proportion of patients with overgrowth and macrocephaly. Future studies should consider endocrine follow-up of children born with in utero Zika exposure to explore these findings' possible aetiologies. CONCLUSION: We found a high proportion of growth alterations, particularly with overgrowth features and macrocephaly. Our study suggests that in addition to neurodevelopment impairment, growth could be altered in infants and children with in utero Zika exposure, even in those patients born without CZS.

Phylodynamic analysis in the understanding of the current COVID-19 pandemic and its utility in vaccine and antiviral design and assessment.

Over the last decades, the use of phylogenetic methods in the study of emerging infectious diseases has gained considerable traction in public health. Particularly, the integration of phylogenetic analyses with the understanding of the pathogen dynamics at the population level has provided powerful tools for epidemiological surveillance systems. In the same way, the development of statistical methods and theory, as well as improvement of computational efficiency for evolutionary analysis, has expanded the use of these tools for vaccine and antiviral development. Today with the Coronavirus Disease 2019 (COVID-19), this seems to be critical. In this article, we discuss how the application of phylodynamic analysis can improve the understanding of current pandemic dynamics as well as the design, selection, and evaluation of vaccine candidates and antivirals.

Dengue and COVID-19, overlapping epidemics? An analysis from Colombia.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread throughout Latin America, a region swept by multiple previous and ongoing epidemics. There are significant concerns that the arrival of COVID-19 is currently overlapping with other viruses, particularly dengue, in various endo-epidemic regions across South America. In this report, we analyzed trends for both viral infections in Colombia during the first 20 epidemiological weeks (EWs) of 2020. From 1st January to 16th May 2020 (EWs, 1-20), a total of 52 679 cases of dengue and 14 943 cases of COVID-19 have been confirmed in Colombia. As both conditions may potentially lead to fatal outcomes, especially in patients with chronic co-morbidities, overlapping infections, and co-occurrence may increase the number of patients requiring intensive care and mechanical ventilation. In regions, such as Valle del Cauca, intensified preparation for such scenarios should be pondered, and further studies should be performed to address this critical issue in a timely matter.