Development and laboratory production of virus-like immune-stimulating complexes based on saponins and evaluation of their adjuvant potential using mice immunisation with influenza antigens

The COVID-19 pandemic has exacerbated the public’s need for effective vaccines. Consequently, significant financial support has been provided to developers of a number of innovative vaccines, including the vaccines with saponin-based adjuvants. In 2021, the World Health Organisation recommended Mosquirix, the first malaria vaccine, which contains a saponin adjuvant. An anti-covid vaccine by Novavax is in the approval phase. A promising approach to vaccine development is presented by the use of virus-like immune-stimulating complexes (ISCOMs) containing saponins and by the creation of combinations of ISCOMs with antigens. The aim of the study was to develop, produce and characterise virus-like immune-stimulating complexes based on saponins of Quillaja saponaria, as well as similar saponins of Russian-sourced Polemonium caeruleum. Materials and methods: The ISCOM adjuvants, Matrix-BQ and Matrix-BP, were produced using liquid chromatography and examined using electron microscopy. Balb/c mice were immunised intraperitoneally and intramuscularly with ISCOM-antigen preparations. Afterwards, the immunised animals were challenged with the influenza virus strain, A/California/4/2009(H1N1)pdm09, adapted and lethal to mice. The serum samples were examined using haemagglutination inhibition (HI) tests. Results: The authors produced the ISCOMs containing saponins of Quillaja saponaria and Polemonium caeruleum. After one intramuscular injection of either of the ISCOM-antigen preparations with 1 µg of each of A/Brisbane/02/2018 (H1N1) pdm09, A/Kansas/14/2017 (H3N2), and B/Phuket/3073/2013 haemagglutinin antigens (HAs), HI tests detected serum antibody titres to the corresponding antigens of ≥1:40. Two intramuscular injections of the ISCOM-antigen preparation containing 50 ng of each of the HAs and Matrix-BQ resulted in a protective response. In some animals, two intraperitoneal injections of ISCOM-antigen preparations resulted in the maximum antibody titre to the A/Kansas/14/2017 (H3N2) vaccine strain of 1:20,480. Two intramuscular injections of a test preparation containing 5 µg, 1 µg, 200 ng, or 50 ng of each of the HAs and Matrix-BQ or a control preparation containing 5 µg, 1 µg, or 200 ng of each of the HAs (commercially available vaccines) to the mice that were afterwards infected with the lethal influenza strain protected the experimental animals from death. Conclusions: The ISCOM-based preparations had high immunostimulatory activity in the mouse-model study. The presented results indicate the potential of further studies of ISCOM-based preparations in terms of both vaccine and immunotherapeutic development

Review on the Epizootiological Situation on Highly Pathogenic Avian Influenza around the World and in Russia in 2022

This paper describes the current situation on highly pathogenic avian influenza virus in 2022 and provides forecast of the possible further spread of avian influenza in Russia. In 2022, the circulation of a wide variety of highly pathogenic avian influenza virus subtypes, which have epizootiological and epidemiological significance, was recorded in the world. Outbreaks caused by highly pathogenic avian influenza virus were reported in over 60 countries. In addition, human infections with influenza viruses of the A(H5Nx) and A(H9N2) subtypes were registered. There was a large-scale epizootic which affected more than 10 regions of the European part of Russia and the Russian Far East in 2022. Outbreaks among wild birds and poultry were caused by the highly pathogenic influenza virus A(H5N1) of the clade 2.3.4.4b, at the same time genetic and antigenic diversity was observed among viruses circulating in Russia. Thus, an essential geographical role of the territory of Russia in the global spread of avian influenza virus has been shown once again, which highlights the importance of continuous avian influenza virus surveillance in the country

Humoral immunity to influenza and severe influenza cases in Russia in 2018-2019

The aim of our work was to investigate the herd immunity to influenza viruses among population of Russia during autumn 2918; evaluation of severe cases of the infection over the season of2018-2019 epidemics, and confirmed cases of influenza in vaccinated persons. A total of 1835 samples of blood serum were studied. Neither sample did react in hemagglutination inhibition test with highly pathogenic A(H5N8) and A(H7N9) viral strains. 41 to 58% of samples, dependent on sampling region, showed significant antibody titers (> 40) against против вакцинного штамма the vaccinal A/Michigan/45/2015 strain (H1N1pdm09). 40 to 63% of the same sera were positive for epidemic A/Lipetsk/1V/2018 strain (H1N1pdm09), isolated at the start of epidemic season (26.11.2018). From 26 to 46% of the samples were seropositive towards vaccinal strain A/Singapore/ INFIMH-16-0019/2016 (H3N2), and 10 to 23% towards Yamagata influenza B genetic strain. Severe influenza cases during the 2018-2019 epidemic season were caused, mainly, by influenza A virus, with predominance of A/H1N1pdm09 (52.5%), with only 3% of cases caused by influenza A viruses. 217 cases of influenza with lethal outcome were confirmed, of them about a half of these cases (44.7%) affected older persons (> 60 years old), 29% were diagnosed in the group of 46-59 years old. Eight lethal cases of influenza infection (3.7%) were documented in the persons vaccinated before the vaccination season. Over 75% of patients with lethal influenza cases had concomitant diseases, with cardiovascular disorders, obesity, diabetes, urogenital diseases, infectious diseases (HIV, hepatitis) being most often. Hence, vaccination against influenza remains the most effective protective tool, especially in the risk groups. The study was performed in the frames of the state task contract (ГЗ-1/16 and ГЗ-2/18)

Initial and severe cases of influenza in 2020-2022 and population immunity prior to epidemic season

The purpose of the present work was to evaluate population immunity to influenza and molecular genetic analysis of influenza viruses detected in the Russian Federation over 2020-2022. In this study, 1344 samples of blood serum collected prior to the 2021-2022 flu season in Siberian, Southern, Far Eastern, Volga and Ural Federal Districts were studied. Seropositivity to the A/Victoria/2570/2019 vaccine strain (H1N1) pdm09 was detected in 25% to 31% of samples from the four federal districts, and in 8% of samples from the Far Eastern Federal District. Seropositivity to the A/Cambodia/e0826360/2020 strain (H3N2) was detected in 24% to 37% of the samples. The lowest population immunity was revealed to the influenza B/Washington/02/2019 vaccine strain (Victoria lineage), with < 10% of serum samples reactive to the studied strain. Since March 2020, the worldwide turnover of all seasonal respiratory viruses has sharply decreased, except of rhinoviruses. From March 2020 to June 2021, we have identified six B/Victoria influenza viruses from sporadic cases of influenza. From June 2021 to the end February 2022, the State Research Center “Vector” received 901 samples positive for influenza A(H3N2) virus RNA, two specimens positive for A(H1N1) pdm09 virus RNA, and 17 samples positive for influenza B. All studied A(H3N2) viruses belonged to the 3C.2a1b.2a2 subclade (Bangladesh group). The two verified A(H1N1) pdm09 influenza viruses belonged to the 6B.1A.5a clade. All studied influenza B viruses were assigned to the B/Victoria genetic lineage, and to 1A.3a2 subclade. The genomes of all identified viruses did not contain mutations of the NA gene responsible for drug resistance to neuraminidase inhibitors, or mutations in РA gene responsible for baloxavir resistance. All viruses tested by fluorescence assay were sensitive to oseltamivir and zanamivir. The worldwide frequency of influenza isolates resistant to antineuraminidase drugs does not exceed 1-2% of cases. Hence, oseltamivir and zanamivir provide effective treatment for seasonal influenza

2019–2020 herd immunity to seasonal influenza viruses prior to epidemic season and rate of severe disease cases

The aim was to analyze heard immunity against influenza viruses as well as severe course of influenza infection prior to the 2019–2020 epidemic season. Methods. Blood sera samples were collected prior to and after conducting population-wide influenza vaccination campaign at the sanitary and epidemiological centers in different regions of the Russian Federation as well as at the Siberian Federal District, respectively. Sera samples were tested by using hemagglutination inhibition (HI) assay with vaccine strains A/Brisbane/02/2018 (H1N1)pdm09, A/Kansas/14/2017 (H3N2), B/Colorado/06/2017 (Victoria lineage). Baseline clinical and autopsy materials in case of influenza infection in vaccinated patients or severe and fatal influenza cases were collected to be tested by RT-PCR at the sanitary and epidemiological centers, Rospotrebnadzor. All influenza-virus positive samples were further sent to the SRC VB “Vector”. Results. A total of 7,896 and 600 blood serum samples were collected from subjects at Siberian Federal District prior to and after the populationwide influenza vaccination campaign, respectively. Prior to the epidemic season, the proportion of individuals seropositive for the influenza A virus subtypes A/(H1N1)pdm09 and A/H3N2 exceeded 50% in most of the regions, whereas frequency of those seropositive for the influenza B virus was profoundly lower ranging from 12 to 46% in the Northwestern Federal District and Volga Federal District, respectively. After influenza vaccination, the percentage of seropositive subjects in the Siberian Federal District increased as follows: for influenza subtype A/(H1N1)pdm09 — from 66 up to 79%, influenza subtype A/H3N2 — from 68 up to 78%, and for influenza B/Victoria — from 32 up to 47%. In 2019–2020, influenza B virus more frequently caused severe infection that agrees with the herd immunity data prior to the epidemic season. However, the vast majority of the influenza cases with fatal outcome was associated with influenza virus A A/H1N1pdm09 subtype. Conclusion. Quality of influenza vaccine, especially that one intended to vaccinate risk group subjects remains a crucial issue for contemporary scientific community. The study was conducted within the framework of the State Assignments no. 1/16 and 2/18

Разработка и лабораторное получение вирусоподобных иммуностимулирующих комплексов на основе сапонинов, оценка их адъювантных свойств при иммунизации мышей гриппозными антигенами

The COVID-19 pandemic has exacerbated the public’s need for effective vaccines. Consequently, significant financial support has been provided to developers of a number of innovative vaccines, including the vaccines with saponin-based adjuvants. In 2021, the World Health Organisation recommended Mosquirix, the first malaria vaccine, which contains a saponin adjuvant. An anti-covid vaccine by Novavax is in the approval phase. A promising approach to vaccine development is presented by the use of virus-like immune-stimulating complexes (ISCOMs) containing saponins and by the creation of combinations of ISCOMs with antigens. The aim of the study was to develop, produce and characterise virus-like immune-stimulating complexes based on saponins of Quillaja saponaria, as well as similar saponins of Russian-sourced Polemonium caeruleum. Materials and methods: The ISCOM adjuvants, Matrix-BQ and Matrix-BP, were produced using liquid chromatography and examined using electron microscopy. Balb/c mice were immunised intraperitoneally and intramuscularly with ISCOM-antigen preparations. Afterwards, the immunised animals were challenged with the influenza virus strain, A/California/4/2009(H1N1)pdm09, adapted and lethal to mice. The serum samples were examined using haemagglutination inhibition (HI) tests. Results: The authors produced the ISCOMs containing saponins of Quillaja saponaria and Polemonium caeruleum. After one intramuscular injection of either of the ISCOM-antigen preparations with 1 µg of each of A/Brisbane/02/2018 (H1N1) pdm09, A/Kansas/14/2017 (H3N2), and B/Phuket/3073/2013 haemagglutinin antigens (HAs), HI tests detected serum antibody titres to the corresponding antigens of ≥1:40. Two intramuscular injections of the ISCOM-antigen preparation containing 50 ng of each of the HAs and Matrix-BQ resulted in a protective response. In some animals, two intraperitoneal injections of ISCOM-antigen preparations resulted in the maximum antibody titre to the A/Kansas/14/2017 (H3N2) vaccine strain of 1:20,480. Two intramuscular injections of a test preparation containing 5 µg, 1 µg, 200 ng, or 50 ng of each of the HAs and Matrix-BQ or a control preparation containing 5 µg, 1 µg, or 200 ng of each of the HAs (commercially available vaccines) to the mice that were afterwards infected with the lethal influenza strain protected the experimental animals from death. Conclusions: The ISCOM-based preparations had high immunostimulatory activity in the mouse-model study. The presented results indicate the potential of further studies of ISCOM-based preparations in terms of both vaccine and immunotherapeutic development.Пандемия COVID-19 обострила потребность общества в эффективных вакцинных препаратах. В этих условиях существенную финансовую поддержку получили разработчики ряда инновационных вакцин, в том числе вакцин, в состав которых входят адъюванты на основе сапонинов. В 2021 г. ВОЗ была одобрена первая противомалярийная вакцина Mosquirix, содержащая сапонины. На стадии одобрения находится вакцина Novavax против COVID-19. Перспективным подходом к созданию вакцин является использование вирусоподобных иммуностимулирующих комплексов (ИСКОМ) на основе сапонинов и создание на их основе комплексов с антигеном (ИСКОМ-антиген). Цель работы: получение и изучение вирусоподобных иммуностимулирующих комплексов на основе сапонинов Квиллайи мыльной (Quillaja saponaria), а также аналогов на основе сапонинов Синюхи голубой (Polemonium caeruleum), полученных из отечественного сырья. Материалы и методы: с применением метода жидкостной хроматографии получали препараты ИСКОМ адъювантов — Матрикс-BQ и Матрикс-BP. Проведено электронно-микроскопическое исследование препаратов. Иммунизацию мышей Balb/c препаратами ИСКОМ-антиген проводили интраперитонеально и внутримышечно. Иммунизированных животных заражали адаптированным летальным для мышей штаммом вируса гриппа A/California/4/2009 (H1N1) pdm09. Образцы сыворотки крови иммунизированных животных исследовали в реакции торможения гемагглютинации (РТГА). Результаты: получены ИСКОМ, содержащие сапонины Синюхи голубой и Квиллайи мыльной. В образцах сыворотки крови животных, однократно внутримышечно иммунизированных препаратом ИСКОМ-антиген, содержащим по 1 мкг гемагглютинина каждого из штаммов вирусов гриппа A/Brisbane/02/2018 (H1N1) pdm09, A/Kansas/14/2017 (H3N2), B/ Phuket/3073/2013, значения титров антител в РТГА составили более 1:40 к соответствующим антигенам. При двукратном внутримышечном введении препарата ИСКОМ-антиген, содержащего 50 нг каждого антигена, был выявлен протективный ответ. Максимальные значения титров антител в РТГА выявлены при двукратном интраперитонеальном введении препарата ИСКОМ-антиген и составили 1:20480 к гемагглютинину вакцинного штамма A/Kansas/14/2017 (H3N2). Показано, что двукратное внутримышечное введение 5 мкг, 1 мкг, 200 нг, 50 нг препарата ИСКОМ-антиген и 5 мкг, 1 мкг, 200 нг контрольного антигена коммерчески доступной вакцины мышам, впоследствии зараженным летальным штаммом вируса гриппа A/California/4/2009 (H1N1)pdm09, защищает экспериментальных животных от гибели. Выводы: полученные препараты на основе ИСКОМ обладали высокой иммуностимулирующей активностью в исследовании на мышиной модели. Представленные результаты свидетельствуют о перспективности дальнейшего изучения препаратов на основе ИСКОМ при разработке как противовирусных, так и иммунокорректирующих препаратов

CHARACTERIZATION OF AVIAN INFLUENZA H5N8 VIRUS STRAINS THAT CAUSED THE OUTBREAKS IN THE RUSSIAN FEDERATION IN 2016–2017

Objective of the study is to investigate biological properties of avian influenza virus strains that caused the outbreaks in Russia in 2016–2017.Materials and methods. The study was performed using advanced virological and molecular-biological methods in state-of-the-art equipment.Results and conclusion. In 2016, the outbreaks among wild birds and poultry caused by highly pathogenic avian influenza H5N8 virus have occurred in the territory of the Russian Federation. In May, 2016 an outbreak of H5N8 among wild birds was registered in the territory of the Republic of Tyva. In October-November, 2016 influenza virus H5N8 was isolated in the territory of the Republics of Tatarstan and Kalmykia, Krasnodar and Astrakhan Regions of Russia. In 2017 avian influenza H5N8 has become widespread in European part of Russia and caused multiple outbreaks among wild birds and poultry. Results of the investigations of the isolated strains show that all of them are highly pathogenic and belong to the clade 2.3.4.4. Molecular-genetic and virological analysis has revealed the differences between the viruses isolated in 2016–2017 and the virus of the same clade 2.3.4.4 that was isolated in 2014

ANALYSIS OF POPULATION IMMUNITY AGAINST INFLUENZA PRIOR TO 2014 AND 2015 EPIDEMIC SEASONS

Aim. Control for the population herd immunity against seasonal influenza viruses as well as for emergence of antibodies against influenza with pandemic potential in human blood sera. Materials and methods. HAI reaction against vaccine and epidemic influenza viruses as well as HPAI viruses A/rook/Chany/32/2015 (H5N1) (clade 2.3.2.1c.) andA/Anhui/01/2013 (H7N9). Results. Among all the sera samples collected in the autumn of 2014 and 2015, none had reacted in HAI against A(H5N1) and A(H7N9) antigens even at 1:10 dilution. Among samples collected in autumn 2014, 41% were positive to A/Califorrna/07/09(HlNlpdm09) virus, 36% - A/Texas/50/2012 (H3N2), 40% - B/Brisbane/60/2008 (Vict.lin.) and 47% reacted in HAI against the B/Massachusetts/2/2012 (Yam.lin.) strain. 22% of all the samples had a titer of at least 40 against all the antigens and only 10% in HAI had a titer of 40 or more against all the vaccine strains. Among the samples collected in autumn 2015, the number of seropositive against A/Califorrna/07/09(HlNlpdm09) varied from 31% in the Urals FD to 46% in the Southern FD. The amount of seropositive against A/Switzerland/9715293/13 (H3N2) strain was at the level of 4 - 13% in all the FDs except Urals, where this parameter was slightly above 30%. The amount of seropositive against vaccine influenza В viruses varied from 23 to 76%. Only 2% of sera had titers in HAI of 40 or above against all the vaccine strains, 29% of all the samples were seronegative. Conclusion. Population immunity in Russia against influenza A(H3N2) is at a very low level, thus socially significant consequences of influenza epidemics in many aspects will depend on the vaccination campaign of autumn 2016

SEVERE CASES OF SEASONAL INFLUENZA IN RUSSIA IN 2015 - 2016 AND 2016 - 2017

Aim. Evaluation of seroprevalence of antibodies to influenza A and В viruses and analysis of specimens from severe or fatal influenza cases in Russia in 2015 - 2016 and 2016 - 2017 flu seasons. Materials and methods. Determination of antibody titer in human serum samples in hemagglutination inhibition assay with reference antigens. Isolation of influenza viruses from nasopharyngeal swabs and autopsy material in cell culture. Characterization ofisolated strains. Results. In 2016, compared to 2015, the proportion of serum samples, containing antibodies to influenza viruses A(H 1N1 pdm09) and A(H3N2), increased. During the 2015-2016 season, elevated number of severe and fatal cases of influenza were registered. The majority of circulated strains belonged to the new clade 6B.1 of A(HlNippdm09 viruses. 1% of analyzed isolates carried H275Y amino acid substitution in neuraminidase and were resistant to oseltamivir. In the 2016 - 2017 season, there were less severe cases of influenza. The most prevalent were influenza viruses A(H3N2) and B/Victoria. Isolated H3N2 viruses belonged to the 3C.2a subclade and B/Victoria isolates were from the 1A genetic group. All tested strains were susceptible to neuraminidase inhibitors. Conclusions. Flu seasons 2015 - 2016 and 2016 - 2017 differed in intensity of influenza activity and in the dominant influenza A virus subtype. Immunization with vaccine, comprising new HlNlpdm09-component, is crucial for prophylaxis of influenza infection with viruses from 6B. 1 subclade in the next season. Neuraminidase inhibitors are recommended for influenza treatment