Detection of Toxoplasma gondii Infections using Virus-Like Particles Displaying T. gondii ROP4 Antigen

Toxoplasma gondii ME49 infections are typically diagnosed by serological tests. However, serological diagnosis of RH strain-induced toxoplasmosis remains unknown. In order to develop seradiagnosis of above 2 kinds of infections, we generated recombinant virus-like particles (VLPs) displaying the T. gondii rhoptry protein 4 (ROP4) and evaluated their potential in T. gondii ME49 or RH strain infection diagnostics. Mice were orally infected with either the tachyzoites of T. gondii (RH) or cysts of T. gondii (ME49) at various dosages, and sera were collected at regular intervals. ELISA-based serological tests were performed to assess IgG, IgM, and IgA antibody responses against ROP4 VLP antigen and tissue lysate antigen (TLA). Compared to TLA, IgG, IgM, and IgA levels to ROP4 VLP antigen were significantly higher in the sera of T. gondii RH-infected mice 1 and 2 week post-infection (PI). T. gondii-specific IgG antibody was detected at 1, 2, 4, and 8 week PI in the T. gondii ME49-infected mice with infection dose-dependent manner. These results indicated that the ROP4 VLP antigen was highly sensitive antigens detecting T. gondii RH and ME49 antibodies at an early stage.

Production of novel Spike truncations in Chinese hamster ovary cells

SARS-CoV-2 Spike is a key protein that mediates viral entry into cells and elicits antibody responses. Its importance in infection, diagnostics, and vaccinations has created a large demand for purified Spike for clinical and research applications. Spike is difficult to express, prompting modifications to the protein and expression platforms to improve yields. Alternatively, Spike receptor binding domain (RBD) is commonly expressed with higher titers, though it has lower sensitivity in serological assays. Here, we improve transient Spike expression in Chinese hamster ovary (CHO) cells. We demonstrate that Spike titers increase significantly over the expression period, maximizing at 14 mg/L at day 7. In comparison, RBD titers peak at 54 mg/L at day 3. Next, we develop 8 Spike truncations (T1-T8) in pursuit of a truncation with high expression and antibody binding. The truncations T1 and T4 express at 130 mg/L and 73 mg/L, respectively, which are higher than our RBD titers. Purified proteins were evaluated for binding to antibodies raised against full-length Spike. T1 has similar sensitivity as Spike against a monoclonal antibody and even outperforms Spike for a polyclonal antibody. These results suggest T1 is a promising Spike alternative for use in various applications.

Complex Spectroscopic Study for Fusarium Genus Fungi Infection Diagnostics of “Zalp” Cultivar Oat

At present, one of the critical problems in agriculture is the identification of cereals, including oats, infected by Fusarium spp. genus fungi. Timely diagnostics can prevent the further disease spread and help to identify the already stored infected grains. In this regard, the aim of this work is to develop the spectroscopic approaches that determine the infected grains. As an object of the investigation the “Zalp” cultivar oat, both healthy and infected grains of the 2020 harvest were chosen. The spectroscopic diagnostics included FTIR in the mid-IR region, Raman, and luminescence methods. Combination of chemometric tools with FTIR and Raman spectroscopy allowed obtaining approaches based on identified characteristic spectral features which may be used as infection markers. These approaches make it possible to detect the infection on the grain husk. The carotenoid type fungi pigment was identified within the resonance conditions of Raman scattering excitation. The luminescence study of infected oat husk revealed the presence of characteristic chlorophyll α peak which is absent in healthy grain husk.

Value of positive blood culture for Staphylococcus pettenkoferi - how not to make a mistake while interpreting the microbiological test results

Staphylococcus pettenkoferi is a coagulase negative staphylococcus (CoNS) whose clinical relevance is not fully understood. Hitherto, there are several reports describing the participation of this species in human infections; in most cases S. pettenkoferi was isolated from blood cultures. The purpose of this work is to summarize knowledge about S. pettenkoferi especially in terms of biochemical properties, types of infections caused, factors predisposing to bacteremia and susceptibility to antibiotics. Particular attention was paid to the difficulties in identifying this CoNS bacterium and limitations of microbiological tests. The principles of microbiological bloodstream infection diagnostics and criteria for interpreting test results are summarized, as well. The analysis of published reports and opinions resulted in better characterization of infections in which S. pettenkoferi is the etiological agent. From a clinical point of view, presented knowledge allows to assess the risk of bloodstream infection or sample contamination, help physician to implement the appropriate procedures and making decisions concerning inter alia empirical treatment.