Microevolution of tick-borne encephalitis virus in course of host alternation

AbstractTwo tick-borne encephalitis (TBE) virus variants were studied: mouse brain-adapted strain EK-328 and its derivate adapted to Hyalomma marginatum ticks. The tick-adapted virus exhibited small-plaque phenotype and slower replication in PEK cells, higher yield in ticks, decreased neuroinvasiveness in mice, increased binding to heparin-sepharose. A total of 15 nucleotide substitutions distinguished genomes of these variants, six substitutions resulted in protein sequence alterations, and two were in 5′NTR. Two amino acid substitutions in E protein were responsible for the observed phenotypic differences. Data obtained during reverse passaging of the tick-adapted virus in vivo and in vitro suggest that TBE virus exists as a heterogeneous population that contains virus variants most adapted to reproduction in either ticks or mammals. Host switch results in a change in the ratio of these variants in the population. Plaque purification of the tick-adapted virus resulted in the prompt emergence of new mutants with different virulence for mammals

Evolutionary origins of hepatitis A virus in small mammals

The origins of human hepatitis A virus (HAV) are unknown. We conducted a targeted search for HAV-related viruses in small mammals sampled globally and discovered highly diversified viruses in bats, rodents, hedgehogs, and shrews. We demonstrate that these viruses share unique biological features with HAV, including structural, genomic, antigenic, and pathogenic properties. We found evidence of major shifts of HAV-related viruses between mammalian hosts in the past, suggesting both an origin of this viral genus in small mammals and a zoonotic origin of human HAV. Our data show that risk assessments for emerging viruses can benefit greatly from the analysis of viral infection patterns that evolved within animal reservoirs

Молекулярно-генетическое исследование стабильности и подтверждение подлинности штамма Внуково-32, применяемого для производства вакцины антирабической культуральной концентрированной очищенной инактивированной сухой

Rabies is an acute viral disease caused by a virus of the Rhabdoviridae family of the Lyssavirus genus, which affects the central nervous system and is characterised by absolute mortality. Vaccination is the only way to prevent the disease in humans. One of the products used for vaccination is a cultural concentrated purified inactivated dry rabies vaccine produced by the Federal State Budgetary Institution of Science “Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products of Russian Academy of Sciences” (hereinafter—Chumakov Center).The aim of the study was to examine the structure of the working virus seed of Vnukovo-32 strain used by the Chumakov Center for rabies vaccine production, to assess its genetic stability during production, to explore the possibility of using molecular genetic methods for identification of the production strain in the finished dosage form, and to study the nucleotide sequence of the CVS strain.Materials and methods: Vnukovo-32 rabies virus production strain, working virus seeds, finished batches of the rabies vaccine, CVS fixed rabies virus strain used in the assessment of specific immunity. The molecular genetic study was performed using RT-PCR followed by restriction and sequencing.Results: the paper presents the results of nucleotide sequence analysis of the G gene fragment obtained from the Vnukovo-32 production strain, batches of the working virus seed, and finished batches of the rabies vaccine produced in 2012, 2018, and 2019, and the CVS fixed rabies virus strain used in the assessment of the vaccine’s specific immunity. The study demonstrated that restriction analysis could be used for Vnukovo-32 strain identification at all production stages, including the finished dosage form.Conclusion: Vnukovo-32 and CVS strains used by the Chumakov Center are rabies viruses. Analysis of the nucleotide sequence of the G gene fragment showed that the Vnukovo-32 strain remains stable throughout different production stages. The obtained nucleotide sequence of gene G of the Vnukovo-32 strain was deposited in GenBank (accession number MN116503). The study demonstrated that restriction analysis could be used for Vnukovo-32 strain identification at all production stages, including the finished dosage form. Бешенство – острая вирусная инфекция, вызываемая вирусом семейства Rhabdoviridae рода Lyssavirus и характеризующаяся симптомами поражения центральной нервной системы и абсолютной летальностью. Единственной возможностью предотвратить возникновение данного заболевания у людей является вакцинопрофилактика. Одним из препаратов, используемых в этих целях, является вакцина антирабическая культуральная концентрированная очищенная инактивированная сухая, выпускаемая ФГБНУ «ФНЦИРИП им. М. П. Чумакова РАН».Цель работы: исследование структуры производственного, рабочего посевного вируса бешенства штамма Внуково-32, используемого ФГБНУ «ФНЦИРИП им. М. П. Чумакова РАН» для производства антирабической вакцины, его генетической стабильности на этапах производства, изучение возможности применения молекулярно-генетических методов для подтверждения подлинности производственного штамма в готовой форме вакцины и изучение нуклеотидной последовательности штамма CVS.Материалы и методы: производственный штамм вируса бешенства Внуково-32, рабочие посевные вирусы, готовые серии вакцины антирабической, штамм CVS фиксированного вируса бешенства, используемый для оценки специфического иммунитета. Молекулярно-генетическое исследование проведено с использованием ОТ-ПЦР с последующей рестрикцией и секвенированием.Результаты: представлены результаты анализа нуклеотидных последовательностей фрагмента гена G, полученного из производственного штамма Внуково-32, серий рабочего посевного вируса и готовых серий вакцины антирабической, изготовленных в 2012, 2018, 2019 г., штамма фиксированного вируса бешенства CVS, используемого для оценки специфической активности вакцины. Показана возможность применения рестрикционного анализа для подтверждения подлинности штамма Внуково-32 на всех этапах производства, включая готовую форму вакцины.Заключение: штаммы Внуково-32 и CVS, используемые в ФГБНУ «ФНЦИРИП им. М. П. Чумакова РАН», являются вирусами бешенства. Анализ нуклеотидной последовательности фрагмента гена G показал, что штамм Внуково-32 стабилен на разных этапах производства. Полученная нуклеотидная последовательность гена G штамма Внуково-32 депонирована в GenBank (номер MN116503). Показана возможность применения рестрикционного анализа для подтверждения подлинности штамма Внуково-32 вируса бешенства на всех этапах производства, включая готовую форму вакцины

Клинико-эпидемиологическая характеристика зарегистрированных в Российской Федерации в 2015–2019 гг. случаев острого вялого миелита у детей

Acute flaccid myelitis is a syndrome characterized as the development of acute flaccid paralysis of one or more limbs due to lesions of the anterior horns of the spinal cord, which occurs against the background of a viral infection. More than 300 acute flaccid paralysis cases are registered in the Russian Federation annually, most of them are of a non-infectious etiology. In some cases, patients develop a complex of symptoms similar to poliomyelitis, but without isolation of polioviruses from stool samples. Clinical characteristics of such cases include acute onset, fever, persistent peripheral asymmetric paresis/paralysis of predominantly proximal parts of the limbs, and absence of pathological reflexes, pelvic disturbances, or pyramidal symptoms. In literature, such complex of symptoms is referred as acute flaccid myelitis. We provide an analysis of 18 cases of acute flaccid myelitis detected in the Russian Federation in the period from 2015 to 2019. A clear seasonality of the disease from July to November was noted. Studies of faecal samples, cerebrospinal fluid and blood samples did not reveal the pathogen. In all patients, regardless of therapy, there was a positive trend, but complete recovery was not achieved: paresis of varying severity persisted, mainly in the proximal extremities Therefore, acute flaccid myelitis cases as acute flaccid paralysis cases of unknown etiology require an additional observation and an expanded algorithm of laboratory investigation aimed to finding a possible pathogen.Острый вялый миелит – синдромокомплекс, характеризующийся развитием острого вялого паралича одной или нескольких конечностей вследствие поражения передних рогов спинного мозга, возникающего на фоне вирусной инфекции. Ежегодно в РФ регистрируется >300 случаев острого вялого паралича, подавляющее большинство из них имеют неинфекционную этиологию. В ряде случаев у пациентов развивается комплекс симптомов, сходных с полиомиелитом, но без выделения полиовирусов из образцов стула. Клинические характеристики таких случаев включают острое начало заболевания, лихорадку, наличие стойкого периферического асимметричного пареза/паралича преимущественно проксимальных отделов конечностей при отсутствии патологических рефлексов, тазовых нарушений или пирамидных симптомов. В зарубежной литературе этот симптомокомплекс получил название «острый вялый миелит».В статье приводится анализ 18 случаев острого вялого миелита, выявленных в РФ в период с 2015 по 2019 г. Отмечена четкая сезонность болезни с июля по ноябрь. Исследования образцов фекалий, цереброспинальной жидкости и крови не выявили возбудителя. У всех пациентов независимо от терапии отмечалась положительная динамика, но полного восстановления добиться не удалось: сохранялись парезы разной степени выраженности, преимущественно проксимальных отделов конечностей.Таким образом, случаи острого вялого миелита, определяемые как случаи острого вялого паралича неизвестной этиологии, требуют дополнительного наблюдения и расширенного алгоритма лабораторных исследований, направленных на поиск возможного этиологического агента

Evolutionary origins of hepatitis A virus in small mammals

Hepatitis A virus (HAV) is an ancient and ubiquitous human pathogen recovered previously only from primates. The sole species of the genus Hepatovirus, existing in both enveloped and nonenveloped forms, and with a capsid structure intermediate between that of insect viruses and mammalian picornaviruses, HAV is enigmatic in its origins. We conducted a targeted search for hepatoviruses in 15,987 specimens collected from 209 small mammal species globally and discovered highly diversified viruses in bats, rodents, hedgehogs, and shrews, which by pairwise sequence distance comprise 13 novel Hepatovirus species. Near-complete genomes from nine of these species show conservation of unique hepatovirus features, including predicted internal ribosome entry site structure, a truncated VP4 capsid protein lacking N-terminal myristoylation, a carboxyl-terminal pX extension of VP1, VP2 late domains involved in membrane envelopment, and a cis-acting replication element within the 3Dpol sequence. Antibodies in some bat sera immunoprecipitated and neutralized human HAV, suggesting conservation of critical antigenic determinants. Limited phylogenetic cosegregation among hepatoviruses and their hosts and recombination patterns are indicative of major hepatovirus host shifts in the past. Ancestral state reconstructions suggest a Hepatovirus origin in small insectivorous mammals and a rodent origin of human HAV. Patterns of infection in small mammals mimicked those of human HAV in hepatotropism, fecal shedding, acute nature, and extinction of the virus in a closed host population. The evolutionary conservation of hepatovirus structure and pathogenesis provide novel insight into the origins of HAV and highlight the utility of analyzing animal reservoirs for risk assessment of emerging viruses

Evidence for Novel Hepaciviruses in Rodents

Hepatitis C virus (HCV) is among the most relevant causes of liver cirrhosis and hepatocellular carcinoma. Research is complicated by a lack of accessible small animal models. The systematic investigation of viruses of small mammals could guide efforts to establish such models, while providing insight into viral evolutionary biology. We have assembled the so-far largest collection of small-mammal samples from around the world, qualified to be screened for bloodborne viruses, including sera and organs from 4,770 roden

Crimean-Congo haemorrhagic fever virus: sequence analysis of the small RNA segments from a collection of viruses world wide

Crimean-Congo haemorrhagic fever virus (CCHFv) is a member of the genus Nairovirusin the family Bunyaviridae. It possesses a tripartite, single stranded RNA genome of negative polarity consisting of large (L), medium (M) and small (S) segments. CCHF virus is enzootic in life stock and wild animals in many parts of the Middle East, Asia and Africa and is also recognised in Southeast Europe. Severe disease, manifest as haemorrhagic fever and high mortality rates (up to 50%), is only recognised in humans. We have determined the complete sequence of the small genomic RNA segment from several strains of CCHF virus from outbreaks in Pakistan 2000, Baghdad 1976 and Uzbekistan 1967. Phylogenetic analysis of three datasets of sequences from the small genomic RNA segment available from a range of strains indicates that they can be divided into seven subtypes. Superimposed on this pattern are links between distant geographic locations, pointing to the existence of a global reservoir of CCHFv. In some cases these links may originate from trade in livestock, and long-distance carriage of virus or infected ticks during bird migration