Effect of solar radiation on natural organic matter composition in surface waters and resulting impacts on drinking water treatment.

Solar radiation experiments showed a shift in the composition of natural organic matter (NOM). Due to irradiation, the concentration of high molecular weight (HMW) molecules decreased, and that of the low molecular weight (LMW) fraction increased. Microbiological analyses showed that biodegradation was neglectable. To assess the consequences for water treatment processes, coagulation jar tests were performed by comparing the removal effectivity for NOM fractions from irradiated and unirradiated raw water. The degree of dissolved organic carbon (DOC) removal by coagulation was lower for irradiated waters. As primarily HMW organic compounds are removed by coagulation, the decrease in coagulation performance is attributed to the increase in the LMW concentration due to photochemical reactions induced by solar radiation. Flocs were about 15% larger for irradiated water. Possibilities to adapt water treatment to respond to changes in DOC composition and concentration are outlined. Ozonation-biofiltration is judged as the most promising treatment process to cope with climate change-related challenges in drinking water treatment.

The complex formation of influenza virus envelope glycoproteins with outer membrane proteins of Neisseria meningitidis or Borrelia burgdorferi.

The isolation of influenza virus envelope glycoproteins was achieved by one-step procedure consisting of treatment of purified virus with zwitterionic detergent and separation of viral constituents by sucrose density gradient centrifugation. Viral glycoproteins and proteins of outer membrane of N. meningitidis or B. burgdorferi formed complexes after removal of the detergent by dialysis. Complexing of viral glycoproteins and bacterial proteins was monitored by gel chromatography on Sepharose 6B, polyacrylamide gel electrophoresis and electron microscopy. It was demonstrated by immunoblot analysis, that virus-spirochete complexes elicited formation of antibodies in mice directed against osp A and osp B of spirochete, as well as against viral glycoproteins, respectively.

The complex of flavivirus envelope polypeptide with meningococcal proteosomes elicits formation of virus-neutralizing antibodies.

Polypeptide E of tick-borne encephalitis virus was isolated in sucrose density gradient and mixed with equal weight portion of meningococcal proteosomes in the presence of N-dodecyl-N,N-dimethylglycine. Mutual complexing of viral and bacterial molecules occurred after removal of detergent by dialysis. Complexed particles appeared in the electron microscope as 40-50 microns thick short-rod structures covered on their surface with both, delicate poppy-like grains, or envelope subunit-like clustered molecules. Even when applied without adjuvant, the complex of tick-borne encephalitis virus polypeptide E with meningococcal proteosomes elicited in mice a marked antiviral as well as antibacterial humoral response.

Purification of murine alpha-herpesvirus and some properties of its DNA.

Strain Sumava Af of murine alpha-herpesvirus (MHV) banded in density gradient at the boundary between 10-20% and 20-30% Ficoll solution. In electron microscope, the partially purified virus visualized by negative staining exhibited intact or disrupted envelope structures and capsid particles of about 110 nm in outer diameter. The DNA extracted from partially purified virus and further purified in CsCl density gradient had the Tm-value of 79.0 degrees C. The molecular weight of about 90 million daltons was calculated for viral DNA according to its migration in agarose gel.

Polyacrylamide gel electrophoresis of the Kemerovo virus RNA.

Ribonuclease (RNase)-resistant RNA was isolated from partially purified Kemerovo virus by gel chromatography and or sucrose density gradient centrifugation. Double-stranded (ds) RNA only was found in the purified viral cores. The RNAs from both sources exhibited the same pattern of distribution in polyacrylamide gels. Ten dsRNA segments were identified. According to the results of coelectrophoresis of the Kemerovo virus and reovirus dsRNAs, the size of Kemerovo virus genome was estimated to be of about 11.7 X 10(6). The grouping of Kemerovo virus double-stranded segments according to their size in polyacrylamide gels corresponded to the 2:4:3:1 pattern.

Optimalized conditions of tick-borne encephalitis virus production in vitro.

Conditions of the efficient production of tick-borne encephalitis (TBE) virus in chick embryo cell (CEC) monolayer cultures were investigated. The prerequisites of high recovery of the produced virus appeared to be: the use of dense cell monolayers, reasonable frequency of harvests and a suitable buffering of nutrient media. Using low input multiplicity of infection, the peak of the serum-free virus production was observed between 24 and 48 hr post infection (p.i.). The procedure elaborated was useful for isotopic labelling of the virus.

Zonal density gradient electrophoresis of influenza A virus.

Enzymatic activities associated with influenza A virus purified by sedimentation in sucrose density gradient were removed from the virions by sucrose density gradient electrophoresis. A rapidly migrating electrophoretic fraction contained both structural viral polypeptides and chick embryo allantoic fluid polypeptides.

In vitro studies on cell-mediated immune response to tick-borne encephalitis virus: findings in convalescents and human subclinical infections.

Peripheral blood leukocytes from tick-borne encephalitis (TBE) convelescents (manifest and inapparent forms) working with TBE virus-containing material and from individuals without specific serum virus neutralizing antibodies (VNA) were studied in capillary tube leukocyte migration experiments. Partially purified TBE virus preparations were used as antigen. Under standardized conditions a strong inhibitory reaction was observed in convalescents with significantly higher values in persons recovered from an abortive form of infection only. These results differed markedly from values recorded in persons without specific VNA. Significance of correlation between humoral VNA titres and the intensity of the cell-mediated component of the immune response (CM IR), as indicated by leukocyte migration inhibition (LMI) values, was less than P equals 0.25.

Composition of the Zaysan virion.

The sedimentation coefficient of Zaysan virion ribonucleic acid (RNA), estimated by sucrose density gradient centrifugation, was 42 S. Pancreatic ribonuclease digested the viral RNA to acid-soluble fragments. Two viral structural proteins with apparent molecular weight of 50,000 and 30,000 daltons were identified by polyacrylamide gel electrophoresis. A dense, RNA-rich particle, containing the smaller polypeptide, was isolated after mild detergent treatment of Zaysan virus.

Ribonuclease-resistant RNA of Kemerovo virus.

RNA of partially purified Kemerovo virus sedimented in a relatively broad region in sucrose density gradient with a peak at 14 S. Approximately 65% of this RNA was resistant to the action of ribonuclease which indicates the double-stranded nature of Kemerovo virus RNA.