Analysis of cutoff point estimation for determining seropositivity in the context of SARS-CoV-2 infections

In this work will apply mixture models based on distributions from the SMSN family to antibody data against four SARS-CoV-2 virus antigens. Furthermore, since the true infection status of individuals is known a priori, performance measures will be calculated for the methods proposed for cutoff point estimation such as sensitivity, specificity and accuracy. The results of a simulation study will also be presented.

Current state of chikungunya fever laboratory diagnosis (review of literature)

The article is about methods of chikungunya fever laboratory diagnosis. An algorithm for the study of biological material for the presence of antibodies against chikungunya virus and virus antigens is presented. The overview describes the information about commercial immunodiagnostic and genodiagnostic kits and their detailed specifications. The information presented in the review will be useful for doctors of clinical laboratory diagnostics to choose a method and an acceptable test system for laboratory confirmation of Chikungunya fever diagnosis, as well as differential diagnosis with other fevers, which have similar symptoms, common geographical distribution and carriers of infection.

Pathology and Pathogenesis of Lassa Fever: Novel Immunohistochemical Findings in Fatal Cases and Clinico-pathologic Correlation

Background Lassa fever is a zoonotic, acute viral illness first identified in Nigeria in 1969. An estimate shows that the “at risk” seronegative population (in Sierra Leone, Guinea, and Nigeria) may be as high as 59 million, with an annual incidence of all illnesses of three million, and fatalities up to 67,000, demonstrating the serious impact of the disease on the region and global health. Methods Histopathologic evaluation, immunohistochemical assay, and electron microscopic examination were performed on postmortem tissue samples from 12 confirmed Lassa fever cases. Results Lassa fever virus antigens and viral particles were observed in multiple organ systems and cells, including cells in the mononuclear phagocytic system and other specialized cells where it had not been described previously. Conclusions The immunolocalization of Lassa fever virus antigens in fatal cases provides novel insightful information with clinical and pathogenetic implications. The extensive involvement of the mononuclear phagocytic system, including tissue macrophages and endothelial cells suggests participation of inflammatory mediators from this lineage with the resulting vascular dilatation and increasing permeability. Other findings indicate the pathogenesis of LF is multifactorial and additional studies are needed.

Acute Appendicitis Associated with Hantaan Virus Infection

Hantaviruses are Bunyaviridae viruses that cause hemorrhagic fever with renal syndrome (HFRS). Appendicitis caused by Hantaan virus has not been reported previously. An 81-year-old man who underwent laparoscopic appendectomy for suspected appendicitis based on abdominal pain, fever, hypotension, and computed tomography findings. Based on a suspicion of hemorrhagic fever with renal syndrome, the patient’s plasma was simultaneously analyzed using an indirect immunofluorescent antibody assay and nested reverse transcription–polymerase chain reaction (RT-PCR). The appendix tissue was also analyzed using nested RT-PCR and immunohistochemical (IHC) staining to identify the presence of Hantaan virus. Nested RT-PCR detected the presence of Hantaan virus, and indirect immunofluorescent antibody assay results revealed the presence of elevated antibody levels. Furthermore, IHC staining of the appendix tissue confirmed Hantaan virus antigens in the peripheral nerve bundle. Based on these findings, we confirmed the nerve tropism of the Hantaan virus. Hantaan virus in plasma and appendix tissue samples was confirmed using PCR and phylogenetic tree analysis. Moreover, we detected hypertrophy of the submucosa and periappendiceal adipose tissue nerve bundle along with Hantaan virus antigens in peripheral nerve bundles using IHC staining. Hence, we report that Hantaan virus infection may be accompanied by appendicitis.

Self-Amplifying Pestivirus Replicon RNA Encoding Influenza Virus Nucleoprotein and Hemagglutinin Promote Humoral and Cellular Immune Responses in Pigs

Self-amplifying replicon RNA (RepRNA) promotes expansion of mRNA templates encoding genes of interest through their replicative nature, thus providing increased antigen payloads. RepRNA derived from the non-cytopathogenic classical swine fever virus (CSFV) targets monocytes and dendritic cells (DCs), potentially promoting prolonged antigen expression in the DCs, contrasting with cytopathogenic RepRNA. We engineered pestivirus RepRNA constructs encoding influenza virus H5N1 (A/chicken/Yamaguchi/7/2004) nucleoprotein (Rep-NP) or hemagglutinin (Rep-HA). The inherent RNase-sensitivity of RepRNA had to be circumvented to ensure efficient delivery to DCs for intracellular release and RepRNA translation; we have reported how only particular synthetic delivery vehicle formulations are appropriate. The question remained concerning RepRNA packaged in virus replicon particles (VRPs); we have now compared an efficient polyethylenimine (PEI)-based formulation (polyplex) with VRP-delivery as well as naked RepRNA co-administered with the potent bis-(3’,5’)-cyclic dimeric adenosine monophosphate (c-di-AMP) adjuvant. All formulations contained a Rep-HA/Rep-NP mix, to assess the breadth of both humoral and cell-mediated defences against the influenza virus antigens. Assessment employed pigs for their close immunological relationship to humans, and as natural hosts for influenza virus. Animals receiving the VRPs, as well as PEI-delivered RepRNA, displayed strong humoral and cellular responses against both HA and NP, but with VRPs proving to be more efficacious. In contrast, naked RepRNA plus c-di-AMP could induce only low-level immune responses, in one out of five pigs. In conclusion, RepRNA encoding different influenza virus antigens are efficacious for inducing both humoral and cellular immune defences in pigs. Comparisons showed that packaging within VRP remains the most efficacious for delivery leading to induction of immune defences; however, this technology necessitates employment of expensive complementing cell cultures, and VRPs do not target human cells. Therefore, choosing the appropriate synthetic delivery vehicle still offers potential for rapid vaccine design, particularly in the context of the current coronavirus pandemic.

The practice of using a domestic antiviral drug in the etiotropic therapy of acute respiratory viral infection

Aim.Evaluation of efficacy, safety, tolerability, and determination of the optimal dose of riamilovir in patients diagnosed with acute respiratory viral infection (ARVI). Materials and methods.The study included 270 patients with uncomplicated ARVI of mild and moderate severity (with a laboratory-confirmed PCR method for the presence of ARVI antigens, absence of influenza virus antigens). Patients were included in the study after signing an informed consent. Patients were randomized into 3 groups in a 1:1:1 ratio of 90 patients in each group. Completed the study in accordance with the Protocol: 267 patients. The study involved patients diagnosed with ARVI. Results.Confirmed the efficacy, safety and tolerability of the drug riamilovir. Adverse drug reactions associated, in the opinion of the doctor, with taking the drug and resulting in discontinuation of the drug, were not noted in this study. Conclusion.As a result of clinical study, the effectiveness of both ARVI treatment regimens with drug riamilovir has been shown. There were no differences in the effectiveness and safety of the proposed treatment regimens. Practical use of both treatment regimens is recommended. However, according to the authors, taking the drug 3 times a day is much more convenient for patients, improves the quality of life and adherence to therapy.