摘要:

Strains of enterovirus 71 and echovirus type 4 containing aggregates which were poorly neutralized by antibody in cell lines of green monkey kidney origin such as Vero and GMK‐AH1, were as easily neutralized as non‐aggregated strains when grown in human RD cells. The explanation for this may be a lesser degree of aggregation of viral materials originating from RD cells and/or the use of lower doses of virus for neutralization tests in such cells. The latter was a consequence of a higher sensitivity of RD cells to minimal amounts of virus than that shown by Vero and GMK‐AH1 cells. Thus, virus grown in RD, Vero or GMK‐AH1 cells reached a titre 10 to 100 times higher in RD cells than in the other cel

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02405.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Evidence available indicates that the so‐called Dane particles are the hepatitis virus. A DNA polymerase is associated with the core of these particles. The probability that this is the viral DNA polymerase offers the possibility of preventing hepatitis B multiplication by selective inhibition of this enzyme. This investigation reports that trisodium phosphonoformate (PFA) at low concentrations but not phosphonoacetate acid (PAA) inhibits Dane particle associated DNA polymeras

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02406.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

A double diffusion technique for serological typing of Group‐B streptococci is presented. The method is valuable both for type determination on a large scale, as well as for evaluation of the specificity of type antisera. As in previously published methods, HCl‐extracted antigens are used. The preparation of type antisera is described and the reactions of some selected sera are given in figures. The advantages of the method are good economy of antisera and easy recognition of weak and/or unspecific precipitates. The method is especially useful in epidemiological investigati

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02407.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Strains ofEscherichia coliwith different O and K antigens were investigated with respect to physicochemical surface characteristics and liability to phagocytosis. Using two‐phase partitioning analysis for the surface characterization, three main groups of strains emerged: Group I (O1:K1, O2:K1, O3:K2ab) showing both smooth hydrophilic O antigens and negatively‐charged K antigen which rendered the strains maximally resistant to phagocytosis. Group II (O55:K59, O111:K58) showed no acidic K antigen but only smooth hydrophilic O antigen properties. However, these strains were as resistant to phagocytosis as the strains in group I. A third group (O14:K7, O24:K +) contained strains with rough, hydrophobic O antigen and negatively‐charged K antigen. When the K antigen was removed by heat treatment these strains became more sensitive to phagocytosis. Certain other strains (O28:K‐, O56:K + and O118:K‐) did not fit into the three groups. These experiments show that the physicochemical surface effects and biological significance of the K antigen must be evaluated in relation to the properties conveyed by the corresponding O

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02408.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Three groups ofE. colibacteria isolated from blood, urine and faeces were analysed with respect to physicochemical surface properties in aqueous polymer two‐phase systems. Eighty‐eight per cent of the bacteria isolated from blood cultures showed affinity for the dextran‐rich bottom phase, whereas 60% and 30% of the bacteria isolated from urine and faeces, respectively, collected to the same phase. Further two‐phase analysis indicated that the bacteraemia strains exposed more negative surface than the other groups of bacteria, and that this charge was reduced after heat treatment (70° C, 40 min). These results thus indicate that the strains causing bacteraemia possess similar surface properties, and may have been selected from the more heterogeneous group of bacteria found in urine and faeces. It is further conceivable to propose that bacteria found in the blood expose more heatsensitive, negatively‐charged K antigen than the other groups o

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02409.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Intact sphagnum vegetation from moors in south Sweden and coastal areas of west Norway contained cultivable mycobacteria in 32% and 30% of the specimens, respectively. This frequency of specimens is lower than the 50% previously found in the partly altered moors of northwestern Germany, but the Scandinavian moors contained a larger variety of species. On both intact and altered moorsM. cheloneiandM. sphagni sp. nov.were found, the latter a homologous group of 151 strains. In south Sweden the highest frequency was found inS. balticum, S. recurvum, S. tenellumandS. compactum&molle.(40–65%). In coastal Norway the highest frequency was found inS. rubellum(48%) which offers favourable conditions for the accumulation of solar energy due to the red brown colour in the upper parts. Combined with a high humidity in coastal Norway in summer, this may contribute to the growth of mesophilic mycobacteria. A significant affinity ofM. cheloneitoS. tenellumwas state

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02410.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Combinations of penicillin and chloramphenicol are frequently used initially in the treatment of bacterial meningitis. The simultaneous effects against meningococci of these two drugs were examinedin vitroin a chemically defined, proteinfree medium. The investigation was performed with different combinations of the antibiotics, including optimal concentrations. In most instances, penicillin and chloramphenicol seemed to have an additive, but not an iso‐additive, effect. No antagonism was found, and only one out of nine strains showed indifferenc

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02411.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

A study has been made of the ultrastructure of four strains ofNeisseria meningitidiswhich liberate varying amounts of free endotoxin in a chemically‐defined, protein‐free medium. The two strains which did not release detectable or only sparse amounts of free, filtrable endotoxin were rather uniform in cell size. Their cells appeared to be intact and showed a low tendency to aggregate, In addition cells of these strains showed only sporadic loose, trilaminar membranes and blebs, and free membranous structures were sparse in the medium. The endotoxin releasing strains liberated a high yield of free structures from the outer cell wall into the medium. These structures may represent the lipopolysaccharide (L

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02412.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Nine strains ofStreptococcus sanguiswere examined for competence in genetic transformation with streptomycin resistance (str‐r) as marker. Eight strains belonged to serogroup H and one to the newly‐described serogroup W. Seven of the strains, one of which was the reference strain NCTC 7868 (strain Challis), were competent with str‐r DNA from strain Challis. Strains NCTC 9124 (strain Wicky) and 480 were incompetent. The efficiency of transformation was examined in four different media. Use of Todd Hewitt broth gave frequencies of transformants as high as the more complex media. Addition of serum to the transformation media was not essential for the development of competence. The presence of a competence factor (CF) in the culture filtrate of strain Challis was confirmed. The factor transferred strain Wicky to competence with a great variation in the number of transformants and had no influence on strain 480. On the other hand, this spontaneously incompetent strain became competent after addition of culture filtrate from the competent strain 13b, in contrast to Wicky which now remained incompetent. Thus, it is suggested that several factors are involved in the induction of competence ofS. sa

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02413.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Forty‐one strains ofStreptococcus sanguis(37 of serogroup H and four of the newly‐described serogroup W) were examined semiquantitatively for genetic transformation with streptomycin as marker. The material comprised eight reference laboratory strains and 33 recent isolates. Eighteen strains (16 of serogroup H and two of W) showed spontaneous competence in genetic transformation (without added competence factor, i.e. culture filtrate.). Individual culture filtrates from 19 spontaneously competent and ten incompetent strains were tested for competence‐inducing effect on 23 spontaneously incompetent strains. Competence was induced in 16 of the strains, and 20 of the culture filtrates were active. There was considerable variation with respect to the number of recipient strains which were induced to competence by individual filtrates. Furthermore the recipients varied as regards the number of filtrates that were able to induce that particular strain. There was some relationship, but no complete association, between competence, competence‐inducing ability and the occurrence of spreading zones around the colonies assumed to correspond generally to fimbriation. Thus, three incompetent strains had an active culture filtrate and one spontaneously competent strain had an inactive filtrate. Most, but not all, strains with spontaneous or inducible competence showed spreading, as did most of the strains from which broadly inducing filtrates could be p

ISSN:0304-131X    

DOI:10.1111/j.1699-0463.1979.tb02414.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY