Microbiology Independent Research Journal (MIR Journal)

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Том 4, № 1 (2017)
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1-9 420

In order to decrease the morbidity and mortality caused by seasonal influenza outbreaks, several hundred million vaccine doses are produced worldwide each year. The predominant substrate for the production of the influenza vaccine today is fertilized hen’s eggs. The substitution of the technology based on living organisms by the cell culture-based process offers many advantages, including easier scalability and reduced dependence on the availability of eggs. The African green monkey kidney and Madin Darby canine kidney cell lines support the efficient growth of influenza viruses of different subtypes and, therefore, are considered to be the two most promising alternative substrates for the production of the human influenza vaccine.
However, the pH of endosomes in both of these cell lines is higher than the pH essential for triggering a conformational change of the hemagglutinin (HA) of human influenza viruses, which enables the viral-cellular membrane fusion. This mismatch gives rise to mutations in the HA that lead to an increase of the optimum pH of HA conformational change. As of a result of these mismatches, the HA, and consequently the whole virus, has reduced stability to low pH and elevated temperatures. The production of a vaccine from less stable virus will lead to an elevated HA content in the low pH conformation that can affect the safety, potency, infectivity, and protective efficacy of the final inactivated and live attenuated influenza vaccines.
The main limitations of the cell line-based influenza vaccine technology and the possibilities to preserve the viral stability over the course of influenza vaccine production are discussed in the review.

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В черте города Москвы из фекалий диких водоплавающих птиц изолировали 42 штамма вируса гриппа птиц и проанализировали их на микрочипах «Биогрипп», которые содержат 176 зондов к различным участкам генома вирусов гриппа. Микрочип позволяет определять: 1) субтип поверхностных белков гемагглютинина и нейраминидазы; 2) структуру С-концевой последовательности вирусного белка NS1, влияющую на степень ингибирования транскрипции клеточных хозяйских генов, в том числе ответственных за синтез интерферона; 3) наличие стоп-кодонов и мутацию N66S в рамке считывания вирусного белка PB1-F2, 4) наличие полиосновного сайта протеолитического расщепления гемагглютинина.
Среди изолятов от диких птиц идентифицированы вирусы гриппа субтипов H3N1, H3N6, H3N8, H4N6, H1N1, H5N3 и H11N9. Все они содержали последовательность ESEV на С-конце белка NS1, полноразмерную рамку считывания для белка PB1-F2. Замена N66S в PB1-F2 обнаружена у шести штаммов. Однако такие маркеры патогенности, как последовательность ESEV (лиганд PDZ-домена) в вирусном белке NS1 и замена N66S PB1-F2 в контексте генома вирусов гриппа диких уток, не делали вирус патогенным для мышей. Все изоляты были высокоурожайны в куриных эмбрионах, инфекционны и иммуногенны для мышей, но не вызывали у этих животных клинических симптомов заболевания.

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Forty-two strains of avian influenza viruses were isolated from the wild waterfowls’ feces in the city of Moscow. These viruses, as well as reference strains and some experimental reassortants, were analyzed by microarrays. The microarrays contained 176 probes to the different segments of influenza virus genome. The microarray helps to determine 1) the hemagglutinin and neuraminidase proteins subtype; 2) the primary structure of the C-terminal sequence of the viral NS1 protein, which serves as a ligand for the PDZ domain; 3) the presence of stop codons in the reading frame of PB1-F2 as well as the N66S substitution in the PB1-F2 viral protein; 4) the presence of the polybasic site for hemagglutinin cleavage. The viruses of the H3N1, H3N6, H3N8, H4N6, H1N1, H5N3, and H11N9 subtypes were identified from the group of wild birds’ isolates. All isolates contained the ESEV sequence at the C-terminus of the NS1 protein and the full-length reading frame for the PB1-F2 protein. The replacement of N66S in PB1-F2 was found in six strains. However, the presence of the ESEV sequence (ligand of PDZ domain) in the NS1 virus protein and the N66S substitution in PB1-F2 did not lead to the pathogenicity of these viruses for mice. All isolates demonstrated high yield growth in chicken embryos and were infectious and immunogenic for mice, but did not induce any clinical symptoms.

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Hundreds of thousands of people are dying every year in the world from infections caused by drug resistant bacteria. Antibiotic resistance is a rapidly increasing problem mostly as a result of the worldwide overuse and misuse of antibiotics for conditions that do not require them. The rapid spread of antibiotic resistance in bacteria makes it necessary to intensify the development of new antibiotics and new methods to combat drug resistant bacteria. The goal of this publication is to review the approaches to finding new antibiotics that are active against drug resistant bacteria. The first part of this review is focused on an analysis of the mechanisms of action of antibiotics that are used in clinical practice as well as the mechanisms of bacterial resistance. The molecular structure and modes of action of these antibiotics are reviewed with examples of detailed mechanisms of drugs interaction with the targets in bacteria. General and specific mechanisms of bacterial resistance to these antibiotics are described. Examples of new antibiotics development active against the drug resistant bacteria are presented.

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Pneumonia often occurs as secondary infection post influenza disease and accounts for a large proportion of the morbidity and mortality associated with seasonal and pandemic influenza outbreaks. The antiviral drug triazavirine is licensed in Russia for the treatment and prophylaxis of acute respiratory infections, including influenza A and B viruses. In the present study, we investigated the efficacy of triazavirine in a mouse model of secondary Staphylococcus aureus pneumonia following A/California/04/2009 (H1N1)pdm09 influenza virus infection. We also performed a study of the efficacy of triazavirine against the A/California/04/2009 (H1N1)pdm09 lethal influenza infection in mice. In this model, triazavirine at the dose of 25 mg/kg/day significantly enhanced the survival of animals (60% compared to 20%) and the mean survival time to death, prevented weight loss, and reduced viral titer in the lungs of mice infected with influenza virus. At doses of 50 and 100 mg/kg/day, triazavirine was highly effective in the treatment of the secondary bacterial pneumonia following influenza infection in mice. At these doses, triazavirine protected 67-75% of animals against death, increased the mean survival time to death by twofold, and reduced the virus titer by 2.2-3.0 log10TCID50/ml compared to the mice in the control group. These findings suggest the possible benefit of triazavirine treatment in reducing post influenza pneumonia incidence in humans.

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ISSN 2500-2236 (Online)