Browsing by Author "Petrakova, Natalia"

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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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    The Immunogenicity in Mice of HCV Core Delivered as DNA Is Modulated by Its Capacity to Induce Oxidative Stress and Oxidative Stress Response
    (2019-02-28) Jansons, Juris; Sominskaya, Irina; Petrakova, Natalia; Starodubova, Elizaveta S.; Smirnova, Olga A.; Alekseeva, Ekaterina; Bruvere, Ruta; Eliseeva, Olesja; Skrastina, Dace; Kashuba, Elena; Mihailova, Marija; Kochetkov, Sergey N.; Ivanov, Alexander V.; Isaguliants, Maria G.; Department of Pathology
    HCV core is an attractive HCV vaccine target, however, clinical or preclinical trials of core-based vaccines showed little success. We aimed to delineate what restricts its immunogenicity and improve immunogenic performance in mice. We designed plasmids encoding full-length HCV 1b core and its variants truncated after amino acids (aa) 60, 98, 152, 173, or up to aa 36 using virus-derived or synthetic polynucleotides (core191/60/98/152/173/36_191v or core152s DNA, respectively). We assessed their level of expression, route of degradation, ability to trigger the production of reactive oxygen species/ROS, and to activate the components of the Nrf2/ARE antioxidant defense pathway heme oxygenase 1/HO-1 and NAD(P)H: quinone oxidoreductase/Nqo-1. All core variants with the intact N-terminus induced production of ROS, and up-regulated expression of HO-1 and Nqo-1. The capacity of core variants to induce ROS and up-regulate HO-1 and Nqo-1 expression predetermined their immunogenicity in DNA-immunized BALB/c and C57BL/6 mice. The most immunogenic was core 152s, expressed at a modest level and inducing moderate oxidative stress and oxidative stress response. Thus, immunogenicity of HCV core is shaped by its ability to induce ROS and oxidative stress response. These considerations are important in understanding the mechanisms of viral suppression of cellular immune response and in HCV vaccine design.
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    Prevalence and risk factors of infection with high risk human papilloma viruses among hiv-positive women with clinical manifestations of tuberculosis in a middle-income country
    (2021-06) Isaguliants, Maria; Nosik, Marina; Karlsen, Anastasia; Petrakova, Natalia; Enaeva, Marina; Lebedeva, Natalia; Podchufarova, Daria; Laga, Vita; Gromov, Konstantin; Nazarov, Anatoly; Chowdhury, Sona; Sinitsyn, Mikhail; Sobkin, Alexander; Chistyakova, Natalya; Aleshina, Svetlana; Grabarnik, Alexei; Palefsky, Joel M.; Institute of Microbiology and Virology
    Women living with HIV-1 are at high risk of infection with human papillomavirus of high carcinogenic risk (HR HPVs). M. tuberculosis (TB) promotes HPV infection and increases the risk to develop HPV-associated cancer. Our knowledge of persisting HR HPVs genotypes, and of the factors promoting HR HPV infection in people living with HIV-1 with clinical TB manifestations is sparse. Here, we analyzed 58 women living with HIV-1 with clinical TB manifestations (WLWH with TB) followed up in specialized centers in Russia, a middle income country endemic for HIV-1 and TB, for the presence in cervical smears of DNA of twelve HR HPV genotypes. DNA encoding HPV16 E5, E6/E7 was sequenced. Sociodemographic data of patients was collected by questionnaire. All women were at C2-C3 stages of HIV-infection (by CDC). The majority were over 30 years old, had secondary education, were unemployed, had sexual partners, experienced 2–3 pregnancies and at least one abortion, and were smokers. The most prevalent was HPV16 detected in the cervical smears of 38% of study participants. Altogether 34.5% of study participants were positive for HR HPV types other than HPV16; however, but none of these types was seen in more than 7% of tested samples. Altogether, 20.7% of study participants were positive for several HR HPV types. Infections with HPVs other than HPV16 were common among WLWH with generalized TB receiving combined ART/TB-therapy, and associated with their ability to work, indirectly reflecting both their health and lifestyle. The overall prevalence of HR HPVs was associated with sexual activity of women reflected by the number of pregnancies, and of HPV 16, with young age; none was associated to CD4+-counts, route of HIV-infection, duration of life with HIV, forms of TB-infection, or duration of ART, characterizing the immune status. Thus, WLWH with TB—especially young—were predisposed to infection with HPV16, advancing it as a basis for a therapeutic HPV vaccine. Phylogenetic analysis of HPV16 E5, E6/E7 DNA revealed no common ancestry; sequences were similar to those of the European and American HPV16 strains, indicating that HPV vaccine for WLWH could be the same as HPV16 vaccines developed for the general population. Sociodemographic and health correlates of HR HPV prevalence in WLWH deserve further analysis to develop criteria/recommendations for prophylactic catch-up and therapeutic HPV vaccination of this highly susceptible and vulnerable population group.