Browsing by Author "Dovbenko, Anastasija"

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    Comparative Immunogenicity in Rabbits of the Polypeptides Encoded by the 5′ Terminus of Hepatitis C Virus RNA
    (2015) Sominskaya, Irina; Jansons, Juris; Dovbenko, Anastasija; Petrakova, Natalia; Lieknina, Ilva; Mihailova, Marija; Latyshev, Oleg; Eliseeva, Olesja; Stahovska, Irina; Akopjana, Inara; Petrovskis, Ivars; Isaguliants, Maria; Rīga Stradiņš University
    Recent studies on the primate protection from HCV infection stressed the importance of immune response against structural viral proteins. Strong immune response against nucleocapsid (core) protein was difficult to achieve, requesting further experimentation in large animals. Here, we analyzed the immunogenicity of core aa 1-173, 1-152, and 147-191 and of its main alternative reading frame product F-protein in rabbits. Core aa 147-191 was synthesized; other polypeptides were obtained by expression in E. coli. Rabbits were immunized by polypeptide primes followed by multiple boosts and screened for specific anti-protein and anti-peptide antibodies. Antibody titers to core aa 147-191 reached 105; core aa 1-152, 5 × 105; core aa 1-173 and F-protein, 106. Strong immunogenicity of the last two proteins indicated that they may compete for the induction of immune response. The C-terminally truncated core was also weakly immunogenic on the T-cell level. To enhance core-specific cellular response, we immunized rabbits with the core aa 1-152 gene forbidding F-protein formation. Repeated DNA immunization induced a weak antibody and sustained proliferative response of broad specificity confirming a gain of cellular immunogenicity. Epitopes recognized in rabbits overlapped those in HCV infection. Our data promotes the use of rabbits for the immunogenicity tests of prototype HCV vaccines.
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    EFFICACY OF FACIAL MASK USE IN COVID-19 TRANSMISSION USING A BACTERIAL MODEL
    (2024-03-04) Tomiņa, Katrǐna; Kroiča, Juta; Dovbenko, Anastasija; Skadiņš, Ingus; Department of Biology and Microbiology
    The prevention of COVID-19, caused by SARS-CoV-2, involves reducing transmission of infectious respiratory droplets and aerosols with different methods, including the use of face masks. There have been a variety of studies published about the effectiveness of face masks - they have been recognised as an inexpensive yet expedient prevention method. In this research we aimed to investigate the microbial contamination of used face masks and to compare the results based on mask usage time to determine the efficiency of facial mask use against COVID-19. Microbiological contamination of 51 used face masks was analysed by the imprinting method on suitable cultivation agars and colony forming units were determined. The majority of microorganisms found in our study were those of normal human skin and respiratory tract microbiota. A greater number of bacterial species was found on the outsides of the facial masks, which furthermore increased with prolonged usage time. We conclude that face mask use is effective in both detaining excreted microorganisms as well as protecting the wearer from microbes in the air, and therefore, should be implemented in the prevention strategies of respiratory diseases. Furthermore, our results show the importance of correct facial mask usage by their contamination with a spectrum of microorganisms.
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    Toys in the playrooms of children’s hospitals : A potential source of nosocomial bacterial infections?
    (2021-10-14) Aleksejeva, Viktorija; Dovbenko, Anastasija; Kroiča, Juta; Skadiņš, Ingus; Department of Biology and Microbiology
    Pediatric patients are more susceptible and vulnerable to nosocomial infections, in part because of their nascent and developing immune system and in part due to certain congenital conditions. Consequently, we found limited literature that investigated and reported children’s toys in hospital playrooms as potential reservoirs of pathogenic microbes. Hence, in the present study, we aimed to investigate toys as potential vectors for nosocomial infections in children’s hospitals. Microbiological samples from 120 toys were collected between April 2018 and November 2018. The specimens were cultivated on suitable cultivation agars for 24–72 h at 37◦ C and CFU/cm2 (colony forming units) was determined. Antibiotic susceptibility testing was performed using disc diffusion and E-tests. Our results indicate that 84% of samples were contaminated with different microbes. Four distinct genera and thirty-seven species of bacteria were identified. The most frequently isolated pathogen was Sphingomonas paucimobilis (>603 CFU/cm2 ). Most of the identified microorganisms were members of normal human microbiota. Although Staphylococcus aureus and Acinetobacter baumannii were identified, CFU/cm2 was relatively low and they were found to be sensitive to antibiotics. Additionally, plastic toys showed the highest average CFU/cm2 of 91.9. Our results bolster the need for adoption and strict enforcement of proper disinfection techniques for toys in the hospital playrooms.