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Since its emergence in 2019, coronavirus disease (COVID-19) has spread worldwide and consumed public health resources. However, the world still has to address the burdens of other infectious diseases that continue to thrive. Countries in the tropics and neotropics, including Brazil, are affected by annual, cyclic dengue epidemics. Little is known about the impact of subsequent infections between DENV and SARS-CoV-2. Our study was performed on 400 serum samples collected from laboratory-confirmed COVID-19 patients between January and June 2021, months historically known for DENV outbreaks in Brazil. The samples were tested by serology and molecular assays for the presence of DENV and other arboviruses. While no DENV PCR results were detected, 6% were DENV IgM-positive, and 0.25% were DENV NS1-positive according to ELISA. IgM antibodies were isolated by chromatography, and 62.5% of the samples were positive for neutralizing antibodies (FRNT 80 ) against DENV IgM, suggesting a recent infection. We also observed increased IL-10, TNF-α, and IL-1β levels in patients with overlapping SARS-CoV-2/DENV infections. Intriguingly, diabetes was the only relevant comorbidity (p=0.046). High rates of hospitalization (94.9%) and mortality (50%) were found, with a significant increase in invasive mechanical ventilatory support (86.96%) in SARS-CoV-2/DENV- infected patients, suggesting an impact on patient clinical outcomes. When analyzing previous exposure to DENV, secondary dengue patients infected with SARS-CoV-2 more frequently presented with dyspnea and respiratory distress, longer hospital and intensive care unit (ICU) stays (4 and 20.29 days, respectively) and a higher mortality rate (60%). However, a greater proportion of patients with primary DENV infection had fever and cough than patients with secondary dengue (87.50% vs. 33.33%, p=0.027 for fever). Our data demonstrate that differentiating between the two diseases is a great concern for tropical countries and should be explored to improve patient management.

Accurate testing to detect SARS-CoV-2 RNA is key to counteract the virus spread. Nonetheless, the number of diagnostic laboratories able to perform qPCR tests is limited, particularly in developing countries. We describe the use of a virus-inactivating, denaturing solution (DS) to decrease virus infectivity in clinical specimens without affecting RNA integrity. Swab samples were collected from infected patients and from laboratory personnel using a commercially available viral transport solution and the in-house DS. Samples were tested by RT-qPCR, and exposure to infective viruses was also accessed by ELISA. The DS used did not interfere with viral genome detection and was able to maintain RNA integrity for up to 16 days at room temperature. Furthermore, virus loaded onto DS were inactivated, as attested by attempts to grow SARS-CoV-2 in cell monolayers after DS desalt filtration to remove toxic residues. The DS described here provides a strategy to maintain diagnostic accuracy and protects diagnostic laboratory personnel from accidental infection, as it has helped to protect our lab crew.

Monkeypox virus (MPXV), a genetically distinct member of the Orthopoxvirus genus, causes a febrile vesicular illness in humans and animals, recently renamed Mpox. In 2022, Mpox cases were reported in 115 non-endemic countries, prompting the World Health Organization (WHO) to declare a Public Health Emergency of International Concern. A resurgence of cases in August 2024, centered in the Democratic Republic of Congo and neighboring regions, led to renewed international concern. The Modified Vaccinia Ankara (MVA) virus, originally developed as a safer smallpox vaccine, has demonstrated protective efficacy against MPXV. However, only a limited number of MVA clones have been evaluated or produced specifically for Mpox prevention. In this study, we assessed the immunogenicity and protective efficacy of the LVD/NIAID/NIH MVA1974 clone—previously untested for Mpox—in a mouse model. Mice were immunized intramuscularly with 1 × 108 FFU of the MVA1974 virus using a prime-boost regimen. Immunization induced robust immune responses and provided complete (100 %) protection against a lethal MPXV challenge. Given the current shortage of approved MVA-based vaccines amid growing global demand, alternative MVA clones such as MVA1974 represent promising candidates for further development as Mpox vaccines. •Despite the increasing threat of Mpox global spreading, vaccines are in short supply•MVA1974 is a low passage MVA clone produced in GMP conditions at the NIH/USA•Mice inoculated with MVA1974 produce robust immune responses•MVA1974 immunized mice are completely protected against lethal monkeypox challenge

Serological assays have been widely used to detect anti-SARS-CoV-2 antibodies, which are generated from previous exposure to the virus or after vaccination. The presence of anti-SARS-CoV-2 Nucleocapsid antibodies was recently reported in patients´ urine using an  in-house urine-based ELISA-platform, allowing a non-invasive way to collect clinical samples and assess immune conversion. In the current study, we evaluated and validated another in-house urine-based ELISA for the detection of anti-SARS-CoV-2 Spike antibodies. Three partial recombinant SARS-CoV-2 Spike proteins comprising the Receptor Binding Domain, expressed in eukaryotic or prokaryotic systems, were tested in an ELISA platform against a panel of over 140 urine and paired serum samples collected from 106 patients confirmed positive for SARS-CoV-2 by qRT-PCR. The key findings from our study were that anti-SARS-CoV-2 Spike antibodies could be detected in urine samples and that the prokaryotic expression of the rSARS-CoV-2 Spike protein was not a barrier to obtain relatively high serology efficiency for the urine-based assay. Thus, use of a urine-based ELISA assay with partial rSARS-CoV-2 Spike proteins, expressed in a prokaryotic system, could be considered as a convenient tool for screening for the presence of anti-SARS-CoV-2 Spike antibodies, and overcome the difficulties arising from sample collection and the need for recombinant proteins produced with eukaryotic expression systems.

The emergence of new SARS-CoV-2 variants of concern associated with waning immunity induced by natural infection or vaccines currently in use suggests that the COVID-19 pandemic will become endemic. Investing in new booster vaccines using different platforms is a promising way to enhance protection and keep the disease under control. Here, we evaluated the immunogenicity, efficacy, and safety of the SpiN-Tec vaccine, based on a chimeric recombinant protein (SpiN) adjuvanted with CTVad1 (MF59-based adjuvant), aiming at boosting immunity against variants of concern of SARS-CoV-2. Immunization of K18-hACE-2 transgenic mice and hamsters induced high antibody titers and cellular immune response to the SpiN protein as well as to its components, RBD and N proteins. Importantly in a heterologous prime/boost protocol with a COVID-19 vaccine approved for emergency use (ChAdOx1), SpiN-Tec enhanced the level of circulation neutralizing antibodies (nAb). In addition to protection against the Wuhan isolate, protection against the Delta and Omicron variants was also observed as shown by reduced viral load and lung pathology. Toxicity and safety tests performed in rats demonstrated that the SpiN-Tec vaccine was safe and, based on these results, the SpiN-Tec phase I/II clinical trial was approved.

Fast, precise, and low-cost diagnostic testing to identify persons infected with SARS–CoV-2 virus is pivotal to control the global pandemic of COVID-19 that began in late 2019. The gold standard method of diagnostic recommended is the RT-qPCR test. However, this method is not universally available, and is time-consuming and requires specialized personnel, as well as sophisticated laboratories. Currently, machine learning is a useful predictive tool for biomedical applications, being able to classify data from diverse nature. Relying on the artificial intelligence learning process, spectroscopic data from nasopharyngeal swab and tracheal aspirate samples can be used to leverage characteristic patterns and nuances in healthy and infected body fluids, which allows to identify infection regardless of symptoms or any other clinical or laboratorial tests. Hence, when new measurements are performed on samples of unknown status and the corresponding data is submitted to such an algorithm, it will be possible to predict whether the source individual is infected or not. This work presents a new methodology for rapid and precise label-free diagnosing of SARS-CoV-2 infection in clinical samples, which combines spectroscopic data acquisition and analysis via artificial intelligence algorithms. Our results show an accuracy of 85% for detection of SARS-CoV-2 in nasopharyngeal swab samples collected from asymptomatic patients or with mild symptoms, as well as an accuracy of 97% in tracheal aspirate samples collected from critically ill COVID-19 patients under mechanical ventilation. Moreover, the acquisition and processing of the information is fast, simple, and cheaper than traditional approaches, suggesting this methodology as a promising tool for biomedical diagnosis vis-à-vis the emerging and re-emerging viral SARS-CoV-2 variant threats in the future.

Previous studies have indicated that antibody responses can be robustly induced after the vaccination in individuals previously infected by SARS-CoV-2. To evaluate anti-SARS-CoV-2 humoral responses in vaccinated individuals with or without a previous history of COVID-19, we compared levels of anti-SARS-CoV-2 antibodies in the sera from 21 vaccinees, including COVID-19-recovered or -naïve individuals in different times, before and after immunization with an inactivated COVID-19 vaccine. Anti-SARS-CoV-2-specific antibodies elicited after COVID-19 and/or immunization with an inactivated vaccine were measured by ELISA and Plaque Reduction Neutralizing assays. Antibody kinetics were consistently different between the two vaccine doses for naïve individuals, contrasting with the SARS-CoV-2-recovered subjects in which we observed no additional increase in antibody levels following the second dose. Sera from SARS-CoV2-naïve individuals had no detectable neutralizing activity against lineage B.1 SARS-CoV-2 or Gamma variant five months after the second vaccine dose. Contrarily, SARS-CoV-2-recovered subjects retained considerable neutralizing activity against both viruses. We conclude that a single inactivated SARS-CoV-2 vaccine dose may be sufficient to induce protective antibody responses in individuals with previous history of SARS-CoV-2 infection.

Background : Foot and mouth disease virus (FMDV), a member of the picornaviridae that causes vesicular disease in ungulates, has seven serotypes and a large number of strains, making universal detection challenging. The mature virion is made up of 4 structural proteins, virus protein (VP) 1 – VP4, VP1-VP3 of which form the outer surface of the particle and VP4 largely contained within. Prior to mature virion formation VP2 and VP4 occur together as VP0, a structural component of the pre-capsid which, as a result of containing the internal VP4 sequence, is relatively conserved among all strains and serotypes. Detection of VP0 might therefore represent a universal virus marker. Methods : FMDV virus protein 0 (VP0) was expressed in bacteria as a SUMO fusion protein and the SUMO carrier removed by site specific proteolysis. Rabbit polyvalent sera were generated to the isolated VP0 protein and their reactivity characterised by a number of immunoassays and by epitope mapping on peptide arrays. Results : The specific VP0 serum recognised a variety of FMDV serotypes, as virus and as virus-like-particles, by a variety of assay formats. Epitope mapping showed the predominant epitopes to occur within the unstructured but highly conserved region of the sequence shared among many serotypes. When immunogold stained VLPs were assessed by TEM analysis they revealed exposure of epitopes on the surface of some particles, consistent with particle breathing hitherto reported for some other picornaviruses but not for FMDV. Conclusion : A polyvalent serum based on the VP0 protein of FMDV represents a broadly reactive reagent capable of detection of many if not all FMDV isolates. The suggestion of particle breathing obtained with this serum suggests a reconsideration of the FMDV entry mechanism.

Localized surface plasmon resonance (LSPR) is an optical phenomenon derived from the dielectric properties of noble metals, resulting in a highly change-sensitive spectrum that can be used on a sensor platform. We have used gold nanorods to develop a diagnostic assay to detect antibodies against the nucleocapsid (N) protein of SARS-CoV-2. This approach is particularly valuable, considering the limited role of serology in recognizing acute infections. Gold nanoparticles were coated with the recombinant N protein and characterized by spectroscopy, fluorometry, and electron microscopy. Positive and negative COVID-19 sera samples were initially categorized through qRT-PCR and further validated using an anti-IgG ELISA. The nanosensor was accurate and able to detect very low levels of anti-SARS-CoV-2 antibodies derived from different virus variants early in infection (before 10 days post-infection). The nanoplatform exhibited high sensitivity and specificity, is suitable for mass production, and has easy implementation and automatic read-out.

The SpiN-Tec MCTI UFMG is a chimeric recombinant protein (SpiN) containing the RBD region from the Spike protein (S) fused with the Nucleocapsid protein (N), adjuvanted with a squalene-based emulsion (CTVad1), which was developed as booster COVID-19 vaccine. This is a phase I clinical trial to evaluate safety and reactogenicity. Thirty-six healthy adults aged 18–54, previously vaccinated with two doses of CoronaVac™ (Sinovac) and a booster with the Comirnaty™ Bivalent BA.4/BA.5 (Pfizer-BioNTech), were randomized to receive either SpiN-Tec (20 μg, 60 μg, or 100 μg) or CoviShield™(AstraZeneca). SpiN-Tec was safe and showed a reactogenic profile comparable to CoviShield. Immunogenicity results showed a dose-dependent increase in IgG levels against N and SpiN, peaking at day 28 post-vaccination and declining by day 180. Neutralizing antibody levels against both the Wuhan ancestral and BA1.88 strains showed similar curves presenting no differences between SpiN-Tec and CoviShield. Importantly, SpiN-Tec induced robust IFN-γ production up to 270 days, particularly by CD4+ effector memory T cells, indicating a durable immune response memory. These results indicate the potential of SpiN-Tec as a viable COVID-19 booster vaccine.