The kinetics of interaction of influenza A virus M1 matrix protein with hydrophilic polymer-supported lipid bilayers formed by 1,2-diphytanoyl-sn-glycero-3-phosphocholine and 1,2-diphytanoyl-sn-glycerophospho-l-serine at pH 7.0 was studied by surface plasmon resonance spectroscopy. The M1 protein was shown to bind to the lipid bilayer almost irreversibly to form a monolayer; this is in line with the key function of the M1 protein, that is, formation of the protein envelope of the virion. An increase in the percentage of negatively charged lipids from 0 to 30% leads to a considerable increase in the protein monolayer density and a several-fold increase in the binding constant (K a) of the M1 protein with the lipid bilayer up to (3.60±0.11)·108 L mol–1. The negatively charged lipids in the bilayer appear to promote the manifestation of anisotropic properties of the M1 protein, which enable the protein to form reversible non-monolayer structures on the surface. The M1—M1 interaction was found to be reversible and to be characterized by the binding constant K a = (6.3±0.1)·107 L mol–1.

Adsorption of influenza A viruses and their antibodies on golden surfaces, thin films of polyaniline and polyaniline complex with polysulfonic acids, has been studied. The composition of interpolymer complexes was found to influence both the surface relief of synthesized films and the adsorption efficiency. Moreover, it has been shown that the adsorption of bio-objects increased with a growth of surface roughness of the polymer coatings. It has been suggested that this effect was caused by an tight contact between the studied bioobjects and the surface relief elements of close size. In addition, the surface protuberances can act as active centers of adsorption due to their larger accessibility. The results testify to the potential of application of films composed of interpolymer polyaniline complexes with a developed surface relief as a basis to prepare biosensors that are sensitive to viruses and antibodies.

Adsorption of the viral matrix protein M1 on a substrate simulating the lipid membrane surface of the influenza virus was studied by surface plasmon resonance (SPR). It was found that a decrease of pH leads to an increase of the time to reach the saturated level of adsorption, despite the growth of its initial rate. Adsorption of M1 is irreversible in acidic and neutral media, but in the first case the saturated level of adsorption depends on the protein concentration. It was observed that despite the adsorption irreversibility, acidification of the solution down to pH 4 leads to a partial protein desorption from the adsorbed layer that was formed at pH 7. The findings suggest pH-induced changes in shape of the adsorbed M1 molecules. In an acidic medium, elongated protein molecules adsorb mostly laterally in dilute solutions and more orthogonally in concentrated ones. In a neutral medium, protein molecules take on a compact conformation in the adsorption layer, and its thickness does not depend on the concentration. Apparently, flexible C-terminal domain of the adsorbed protein plays a major role in the pH-induced conformational change.

Методом поверхностного плазмонного резонанса (ППР) исследована адсорбция матриксного вирусного белка М1 на подложке, моделирующей поверхность липидной мембраны вируса гриппа. Установлено, что снижение рН ведет к увеличению времени достижения уровня насыщения адсорбции, несмотря на рост ее начальной скорости. Адсорбция М1 необратима в кислой и нейтральных средах, но в первом случае уровень насыщения адсорбции существенно зависит от концентрации белка. Несмотря на необратимость адсорбции при всех значениях рН закисление раствора до рН 4 приводило к частичной десорбция белка из слоя, сформированного при рН 7. На основании полученных данных сделано предположение о pH-индуцированных изменениях формы адсорбированных молекул М1. В кислой среде вытянутые молекулы белка адсорбируются преимущественно латерально в разбавленных растворах и в большей степени ортогонально в концентрированных растворах. В нейтральной среде молекулы белка приобретают компактную конформацию в адсорбционном слое и его толщина не зависит от концентрации. По-видимому, основную роль в рН-индуцированном изменении формы адсорбированного белка играет его подвижный С-концевой домен.

Adsorption of viral matrix protein M1 on the self-assembled monolayer of carboxyhexadecanthiol molecules simulating the surface of the cell membrane was studied by surface plasmon resonance refractometry technique. It was shown that in the acidic medium (pH 4.0) the fraction of irreversibly adsorbed protein increases with time. The protein formed a monolayer on the surface in concentration range from 50 to 500 nM. It was found that the amount of the adsorbed protein increased more than 3 times in this range. An important observation is that even at the lowest concentrations of the protein its molecules totally occupied the entire surface of the substrate, and a further protein addition did not lead to its further adsorption. To explain this phenomena, it was suggested that the number of M1 bonds with the surface increases during the adsorption, which leads to spreading of the protein molecules. Apparently, this effect is caused by the intrinsic disorder of the C-domain of the protein. It is hypothesized that the disassembly of the protein-lipid envelope of the influenza virus in the acidic medium does not result from desorption of the M1, but it is caused by the weakening of protein-protein bonds.

В экспериментах с участием 20 здоровых испытателей-добровольцев с использованием модели опорной разгрузки методом вывешивания ног исследовали эффекты стимуляции опорных зон стоп в режимах медленной и быстрой ходьбы (75 и 120 шаг/мин). Регистрировали электромиографическую (ЭМГ) активность мышц бедра и голени; для регистрации движений использовали метод видеоанализа. В 80% случаев опорная стимуляция сопровождалась возникновением движений ног испытателей, при этом в 53% случаев эти движения имели выраженный локомоторный характер. В электромиограммах мышц ног при возникновении движений регистрировалась пачечная активность. Последовательность чередования пачек и включения мышц ног была аналогичной таковым в произвольной ходьбе. Пачечная активность возникала с латентным периодом 5.2 ± 1.1 с в мышцах бедра и 14.0 ± 2.8 с – в мышцах голени, частота пачек была отлична от частоты стимуляции. В 31% случаев в ходе стимуляции вызванная активность не носила пачечного характера и характеризовалась постепенным нарастанием амплитуды ЭМГ. Результаты исследования показали, что стимуляция опорных зон стоп активирует структуры локомоторного генератора, и что вызываемый этим раздражением эффект включает запуск не только ритмической, но и неритмической (возможно, позной) компоненты ходьбы.

The effects of mechanical stimulation of the soles’ support zones in the modes of slow and fast walking (75 and 120 steps per minute) were studied using the model of supportlessness (legs suspension). 20 healthy subjects participated in the study. EMG activity of hip and shin muscles was recorded. Kinematics of leg movements was assessed with the use of videoanalysis system. In 80% of cases support stimulation was followed by leg movements, in 69% of which they had characteristics of locomotions being accompanied by the burst-like electromyographic activities. The order of involvement of leg muscles and organization of antagonistic muscles activities were analogous to those of voluntary walking. The latencies of electromyographic activity in hip and shin muscles composed 5.17 ± 1.08 and 14.01 ± 2.82 s, respectively, the frequencies of bursts differed significantly depending on stimulation frequency. In 31% of cases the electromyographical activity following the stimulation of the soles’ support zones had not burst-like but uninterrupted pattern. Its amplitude rose smoothly reaching a certain level that was subsequently maintained. Results of the study showed that soles’ support zones stimulation in the mode of locomotion could activate a locomotor generator provoking the appearance of locomotion-like activity and that effect evoked by this stimulation includes not only rhythmical but also non-rhythmical (probably postural) components of walking.