[Prion diseases and the biosecurity problems.]

The review presents the current state of the problem of prions and prion diseases with an emphasis on theepidemiological and epizootological risks of pathogens that cause fatal neurodegenerative diseases in humans and animals. The results of molecular genetic studies of the conversion of normal PrPc prion protein molecules to infectious forms of PrPd, resistance to physical disinfection methods, in particular exceptional thermal stability, and their ability to overcome interspecific barriers, while increasing virulence, are described. The possibility of infection not only by nutrition, when eating even heat-treated meat of sick animals, but also due to surgical interventions, especially neurosurgical and ophthalmic, as well as the use of immunobiological preparations, are emphasized. Since there are currently no means for the effective treatment of prion diseases in the world, attention is drawn to the high degree of relevance for the biosafety of the country to develop domestic highly sensitive test systems that can effectively detect prion infectious protein in vivo at the preclinical stage of the disease. The latest methods of automatic protein amplification and identification of prion proteins are briefly described as the most promising areas of research in the field of diagnosis of prion diseases.

Human rotavirus infection. Strategies for the vaccinal prevention.

Rotavirus was first isolated in 1973 in Australia from children with diarrhea. Hundreds of thousands of children die annually in developing countries from this virus with the mortality peaks in the most impoverished among them. According to wHo, rotavirus infection claims about 440 thousands children lives each year, being third in the mortality rate after pneumonia and malaria. Rotavirus is widely spread throughout the world and by the age of five years almost every child encountered this pathogen at least once. Rotavirus has a high genetic and antigenic diversity. The most important for humans is the group A rotavirus, and the most common by far genotypes are G1P [8], G2P [4], G3P [8], G4P [8], G9P [8], and to a lesser extent G12P [8]. There are three gene constellations described in rotavirus designated Wa, Ds-1, and Au-1. It is believed that they originated from rotaviruses of pigs, cattle, dogs, and cats, respectively. Cases of rotavirus interspecies transmission from animal to humans were reported. The first vaccines against rotavirus infection were based on naturally attenuated virus of the animal origin. Their efficiency, especially in developing countries, was inadequate, but today China and India use vaccines based on animal rotaviruses. Using the method of gene reassortation with the cattle rotavirus WC3 as a backbone, pentavalent vaccine against most common human rotavirus serotypes was developed and now successfully used as RotaTeq. The ability of rotavirus to protect against heterologous isolates was taken into account in the development of other vaccine, Rotarix, created on the basis of rotavirus genotype G1P1A [8]. The efficacy of these vaccines in developing countries is significantly reduced (51%), the cost of a dose is high, and so the search for more effective, safe, and inexpensive vaccines against rotavirus continues around the world.

Structural and functional properties of Langmuir films of antibodies based on amphiphilic polyelectrolytes.

We optimized the procedure for the formation of Langmuir films of antibodies based on amphiphilic polyelectrolytes and studied the physicochemical and immunochemical properties of the films obtained. Their immunochemical properties were compared with the immunochemical activity of antibodies in Langmuir films without amphiphilic polyelectrolytes and with antibodies adsorbed on the surface of polystyrene and graphite. The efficiency of immune adsorption by the films based on amphiphilic polyelectrolytes was shown to be greater; the affinity of antibodies and surface concentration of their active conformation depended on the type of amphiphilic polyelectrolytes used to obtain the films. We investigated the structure of these films at the surface of highly oriented pyrolytic graphite using the method of atomic force microscopy. Changes in the structure of the films under study caused by the increase of surface pressure were demonstrated.

Adsorption chromatography on Toyopearl: a single-step alternative to salt fractionation of protein mixtures.

Toyopearl media for gel filtration tend to adsorb proteins at high ionic strength, presumably by hydrogen bonding. This is used in the technique proposed here for resolution of crude protein mixtures and initial purification of their components. Proteins can be selectively adsorbed on a column of Toyopearl at high ammonium sulfate concentration and then eluted by decreasing the salt concentration. This single-step procedure can replace the usual salt fractionation of protein mixtures, which is demonstrated with yeast cytochrome oxidase.

Proteolysis of the products of mitochondrial protein synthesis in yeast mitochondria and submitochondrial particles.

Degradation of mitochondrial translation products in Saccharomyces cerevisiae mitochondria was studied by selectively labelling these entities in vivo in the presence of cycloheximide and following their fate in isolated mitochondria. One-third to one-half of the mitochondrial translation products are shown to be degraded, depending on the culture growth phase, with an approximate half-life of 35 min. This process is shown to be ATP-dependent, enhanced in the presence of puromycin and inhibited by chloramphenicol. Further, the proteolysis is suppressed by detergents and is insensitive to antisera against yeast proteinases A and B when measured in mitochondria or 'inside-out' submitochondrial particles. It is concluded that the breakdown of mitochondrial translation products is most probably due to the action of endogenous proteinase(s) associated with the mitochondrial inner membrane. This proteinase is inhibited by phenylmethanesulphonyl fluoride, leupeptin, antipain and chymostatin.

The lability of the products of mitochondrial protein synthesis in Saccharomyces cerevisiae. A novel method for protein half-life determination.

A method for the determination of the half-life of mitochondrial translation products in yeast in vivo is proposed. The method uses inhibitors of cytoplasmic and mitochondrial protein synthesis and is based on double-labelling pulse-chase techniques, the second label being used to estimate 'post-incorporation' during the 'chase'. For the first time the difference between post-incroporation and the widely known recycling of the label is considered. These studies show that, in the turnover of mitochondrial translation products, the problem is of post-incorporation into mitochondria (especially from the cell sap) is predominant. The results obtained with this procedure indicate that the half-life of the products of mitochondrial protein synthesis in yeast at the late-exponential phase is about 60 min. The results suggest that mitochondrial transplantation products are subject to proteolysis to acid-soluble forms.