STUDIES IN THE VARIABILITY OF TUBERCLE BACILLI.: II. CORRELATION OF COLONY STRUCTURE, ACID AGGLUTINATION AND VIRULENCE

1931 ◽  
Vol 5 (1) ◽  
pp. 111-121 ◽  
Author(s):  
Guilford B. Reed ◽  
Christine E. Rice
Keyword(s):  
Colony Structure ◽  
Colony Form ◽  
High Acidity ◽  
Solid Media ◽  
Fluid Media ◽  
High Virulence ◽  
History Of ◽  
Highly Virulent

Twenty-eight cultures of tubercle bacilli including human, bovine and avian forms from widely differing sources have been compared as to colony structure, habit of growth in fluid media, acid agglutination and virulence for animals.It was found that the recently isolated highly virulent cultures and all the cultures with a long history of high virulence grew on solid media in S colony form; on fluid media, in the case of bovine and human types, as a continuous veil-like pellicle, in the avian types as a diffuse suspension; all were agglutinated only at a high acidity. All the a virulent or low virulent cultures or those with a history of loss of virulence now grow on solid media in R colonies; in fluid media as a heavy pellicle tending to separate into discrete islands; and are agglutinated at a relatively low acidity.

scholarly journals Cross-talk among flesh-eating Aeromonas hydrophila strains in mixed infection leading to necrotizing fasciitis

2016 ◽  
Vol 113 (3) ◽  
pp. 722-727 ◽  
Author(s):  
Duraisamy Ponnusamy ◽  
Elena V. Kozlova ◽  
Jian Sha ◽  
Tatiana E. Erova ◽  
Sasha R. Azar ◽  
...  
Keyword(s):  
Necrotizing Fasciitis ◽  
Mixed Infection ◽  
Aeromonas Hydrophila ◽  
Case Fatality ◽  
Host Immune System ◽  
Complex Interactions ◽  
Solid Media ◽  
Multiple Strains ◽  
Highly Virulent

Necrotizing fasciitis (NF) caused by flesh-eating bacteria is associated with high case fatality. In an earlier study, we reported infection of an immunocompetent individual with multiple strains of Aeromonas hydrophila (NF1–NF4), the latter three constituted a clonal group whereas NF1 was phylogenetically distinct. To understand the complex interactions of these strains in NF pathophysiology, a mouse model was used, whereby either single or mixed A. hydrophila strains were injected intramuscularly. NF2, which harbors exotoxin A (exoA) gene, was highly virulent when injected alone, but its virulence was attenuated in the presence of NF1 (exoA-minus). NF1 alone, although not lethal to animals, became highly virulent when combined with NF2, its virulence augmented by cis-exoA expression when injected alone in mice. Based on metagenomics and microbiological analyses, it was found that, in mixed infection, NF1 selectively disseminated to mouse peripheral organs, whereas the other strains (NF2, NF3, and NF4) were confined to the injection site and eventually cleared. In vitro studies showed NF2 to be more effectively phagocytized and killed by macrophages than NF1. NF1 inhibited growth of NF2 on solid media, but ExoA of NF2 augmented virulence of NF1 and the presence of NF1 facilitated clearance of NF2 from animals either by enhanced priming of host immune system or direct killing via a contact-dependent mechanism.

scholarly journals IMMUNIZATION OF GUINEA PIGS WITH A MODIFIED STRAIN OF LYMPHOCYTIC CHORIOMENINGITIS VIRUS

1937 ◽  
Vol 66 (3) ◽  
pp. 317-324 ◽  
Author(s):  
Erich Traub
Keyword(s):  
Guinea Pigs ◽  
Serial Passage ◽  
Lymphocytic Choriomeningitis ◽  
White Mouse ◽  
Lymphocytic Choriomeningitis Virus ◽  
High Virulence ◽  
Different Strains ◽  
Highly Virulent

A strain of choriomeningitis virus which was highly virulent for guinea pigs, as isolated from a naturally infected white mouse, has been markedly attenuated for guinea pigs by serial intracerebral passage through white mice. The change of virulence occurred before the 8th serial passage. The modified virus as a rule produces fever in guinea pigs but no other symptoms, and the infection is followed by a very solid immunity. Parallel passages of the same strain through guinea pigs have maintained its high virulence for this species but slightly reduced its pathogenicity for mice. These observations indicate that the differences in virulence for guinea pigs noted before (1, 2) with different strains of choriomeningitis virus obtained from infected stock mice may be due not only to differences in the susceptibility of guinea pigs but also to variations in the virulence of the virus. A marked degree of resistance was demonstrable in several guinea pigs on the 4th, 8th, and 10th day after injection with modified virus, when antivirus could not yet be detected in the serum. Circulating antivirus appears therefore to play a secondary part in their immunity, which seems to be closely associated with the tissues as in mice.

Acoustic Band Gap Extension in One-Dimensional Solid/Fluid Phononic Crystal Heterostructure

2014 ◽  
Vol 22 (04) ◽  
pp. 1450010 ◽  
Author(s):  
Xu Yang Xiao ◽  
Run Ping Chen
Keyword(s):  
Band Gap ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Wide Band ◽  
Normal Incidence ◽  
Wide Band Gap ◽  
Longitudinal Waves ◽  
One Dimensional ◽  
Solid Media ◽  
Fluid Media

The propagation of elastic longitudinal waves in one-dimensional (1D) phononic crystals (PNCs) consisting of alternating solid and fluid media is comprehensively analyzed in theory. We demonstrate the acoustic band gap (ABG) structure determined by the dispersion relation for longitudinal waves at normal incidence. According to the band structure, we design a sub-PNC by setting a reasonable thickness ratio of fluid and solid media, and then form a phononic heterostructure by merging this PNC and other PNC designed in advance. We have shown that the wide band gap exists in such a phononic heterostructure for elastic longitudinal waves at normal incidence. For oblique incidence, the wide band gap shifts towards high frequency regions, meanwhile a low-frequency band gap is split.

scholarly journals Transient virulence of emerging pathogens

2009 ◽  
Vol 7 (46) ◽  
pp. 811-822 ◽  
Author(s):  
Benjamin M. Bolker ◽  
Arjun Nanda ◽  
Dharmini Shah
Keyword(s):  
Genetic Variance ◽  
Evolutionary Dynamics ◽  
Growth Conditions ◽  
Emerging Pathogens ◽  
Potential Significance ◽  
Phase Selection ◽  
Transmission Rates ◽  
Virulence Evolution ◽  
High Virulence ◽  
Highly Virulent

Should emerging pathogens be unusually virulent? If so, why? Existing theories of virulence evolution based on a tradeoff between high transmission rates and long infectious periods imply that epidemic growth conditions will select for higher virulence, possibly leading to a transient peak in virulence near the beginning of an epidemic. This transient selection could lead to high virulence in emerging pathogens. Using a simple model of the epidemiological and evolutionary dynamics of emerging pathogens, along with rough estimates of parameters for pathogens such as severe acute respiratory syndrome, West Nile virus and myxomatosis, we estimated the potential magnitude and timing of such transient virulence peaks. Pathogens that are moderately evolvable, highly transmissible, and highly virulent at equilibrium could briefly double their virulence during an epidemic; thus, epidemic-phase selection could contribute significantly to the virulence of emerging pathogens. In order to further assess the potential significance of this mechanism, we bring together data from the literature for the shapes of tradeoff curves for several pathogens (myxomatosis, HIV, and a parasite of Daphnia ) and the level of genetic variation for virulence for one (myxomatosis). We discuss the need for better data on tradeoff curves and genetic variance in order to evaluate the plausibility of various scenarios of virulence evolution.

scholarly journals THE MORPHOLOGY OF BACTERIUM SHIGAE CULTIVATED ON VARIOUS MEDIA FAVORABLE TO THE DEVELOPMENT OF FILTERABILITY AND LIFE CYCLE FORMS

1933 ◽  
Vol 57 (1) ◽  
pp. 165-180 ◽  
Author(s):  
Ralph W. G. Wyckoff
Keyword(s):  
Life Cycle ◽  
Lithium Chloride ◽  
Motion Picture ◽  
Simple Explanation ◽  
Nutrient Media ◽  
Solid Media ◽  
History Of ◽  
Micro Motion ◽  
Pass Through

A simple micro motion picture apparatus has been developed which is so inexpensive to construct and to operate that it can be used regularly for bacteriological research. With this equipment about 6000 feet of film representing 600 hours of photography have been made of B. shigae growing upon various solid media. These pictures illustrate the principal phenomena accompanying the development of this organism on ordinary nutrient media, on media consisting exclusively of either peptones or proteins, and on media containing small amounts of LiCl. Information has thus been gained concerning the existence of a life cycle in the Shiga bacillus and concerning its filterability through Berkefeld filters. The formation and history of the various "life cycle forms" are recorded but the evidence does not point to them as phases of actual cycles. In "filterable" B. shigae cultures—such as those grown in the so-called "K" broth or in lithium chloride-containing media—many small and short rods are present. It has been found that these dwarfed organisms pass through filters impervious to the cells of rapidly growing normal cultures. This offers a simple explanation of "quick reversions." The present experiments do not provide conclusive information concerning the slower reversions which are supposed to occur only after many days of treatment and incubation.

VARIATION IN CLOSTRIDIUM WELCHII

1933 ◽  
Vol 9 (4) ◽  
pp. 350-359 ◽  
Author(s):  
J. H. Orr ◽  
J. E. Josephson ◽  
Mary C. Baker ◽  
G. B. Reed
Keyword(s):  
Single Cell ◽  
Blood Agar ◽  
True Breeding ◽  
Fluid Media ◽  
Serial Cultivation ◽  
Killing Action ◽  
Highly Virulent

In this paper it is shown that by plating cultures of Cl. welchii, on a suitable hormone-blood agar, two distinct colony types, regarded as S and R, and frequently intermediate types, may be isolated. Once isolated and stabilized by continued cultivation and selection at least the two more extreme types show true breeding properties. Serial cultivation in various fluid media, particularly Robertson's chopped meat, has resulted in both S to R and R to S variation. This has been observed in strains purified by colony selection and by single cell isolation.The S type has proved to be highly virulent for pigeons, the R type much less virulent but there is some evidence that the apparent killing action of R types may result from in vivo dissociation of the R to S. Both S and R types are shown to yield hemotoxin which is neutralized by antitoxin but under similar conditions S types produce 10 to 20 times more toxin than R types.

STUDIES IN THE VARIABILITY OF TUBERCLE BACILLI: I. A RAPID-GROWING BOVINE TYPE

1931 ◽  
Vol 4 (4) ◽  
pp. 389-398 ◽  
Author(s):  
Guilford B. Reed ◽  
Christine E. Rice
Keyword(s):  
Related Species ◽  
Tubercle Bacillus ◽  
Solid Media ◽  
Fluid Media ◽  
Acid Fluid ◽  
Bovine Type

Variability studies have been carried out on a considerable series of cultures of tubercle bacilli and related species of acid-fast bacteria. The present paper deals with a rapid-growing strain of the bovine tubercle bacillus. The results are in conformity with claims recently made by Petroff that certain types of tubercle bacilli undergo dissociation.It is shown that this avirulent, rapid-growing strain consists of R types which appear to be stable in acid fluid media and more or less stable on solid media. Rapid transfers through strongly alkaline fluids or growth in large volumes of similar media result in appreciable dissociation into S types. The S types were unstable, particularly in acid fluid media, and readily reverted to the R form.

High virulence in hamsters of four dominant Leptospira serovars isolated from rats in the Philippines

Microbiology ◽  
2014 ◽  
Vol 160 (2) ◽  
pp. 418-428 ◽  
Author(s):  
Sharon Y. A. M. Villanueva ◽  
Mitsumasa Saito ◽  
Yutaka Tsutsumi ◽  
Takaya Segawa ◽  
Rubelia A. Baterna ◽  
...  
Keyword(s):  
Renal Damage ◽  
The Philippines ◽  
Pulmonary Haemorrhage ◽  
Human Leptospirosis ◽  
Splenic Macrophages ◽  
High Virulence ◽  
Leptospira Serovars ◽  
Leptospira Borgpetersenii ◽  
Highly Virulent ◽  
Lethal Doses

Leptospirosis is caused by pathogenic species of Leptospira. The aim of this study was to determine and characterize the pathogenicity of four dominant Leptospira isolates prevailing among rats in the Philippines. The isolates were Leptospira interrogans serovar Manilae strain K64, L. interrogans serovar Losbanos strain K37, L. interrogans serovar Ratnapura strain K5 and Leptospira borgpetersenii serovar Javanica strain K6. Pathogenicities were studied using hamsters, which reproduce severe human leptospirosis. The minimum lethal doses were 100 ( = 1) leptospires for K64, K37 and K5, and 101 leptospires for K6. Weight loss amongst the Leptospira-infected hamsters was observed from 1 day before death (K64-, K37- and K5-infected hamsters) to as much as 1 week before death for K6-infected hamsters. Similar and varied gross and microscopic lesions were observed amongst infected hamsters, even for strains belonging to the same species (i.e. L. interrogans). The most significant and common histopathological findings were congestion of the glomerulus, disarrangement of hepatic cords and erythrophagocytosis. Other findings were foamy splenic macrophages for K6, severe petechial pulmonary haemorrhage for K64, and hematuria and severe pulmonary congestion for K37. Immunostaining and culture revealed the presence of leptospires in different organs of the infected hamsters. Based on these results, Leptospira isolates from rats in the Philippines were shown to be highly virulent, causing pulmonary haemorrhage, severe hepato-renal damage and death in hamsters even at lower doses. The present findings on experimental leptospirosis support clinical data showing that patients with severe manifestations of leptospirosis, such as pulmonary haemorrhage, are increasing in the Philippines. These findings may serve as a basis to strengthen the early diagnosis and treatment of human leptospirosis.

scholarly journals Genetic diversity of Colletotrichum lupini and its virulence on white and Andean lupin

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. A. Alkemade ◽  
M. M. Messmer ◽  
R. T. Voegele ◽  
M. R. Finckh ◽  
P. Hohmann
Keyword(s):  
Fungal Pathogen ◽  
Intraspecific Diversity ◽  
White Lupin ◽  
Breeding Programs ◽  
Center Of Origin ◽  
Genetic Groups ◽  
Virulent Strains ◽  
High Virulence ◽  
Colletotrichum Lupini ◽  
Highly Virulent

AbstractLupin cultivation worldwide is threatened by anthracnose, a destructive disease caused by the seed- and air-borne fungal pathogen Colletotrichum lupini. In this study we explored the intraspecific diversity of 39 C. lupini isolates collected from different lupin cultivating regions around the world, and representative isolates were screened for their pathogenicity and virulence on white and Andean lupin. Multi-locus phylogeny and morphological characterizations showed intraspecific diversity to be greater than previously shown, distinguishing a total of six genetic groups and ten distinct morphotypes. Highest diversity was found across South America, indicating it as the center of origin of C. lupini. The isolates that correspond to the current pandemic belong to a genetic and morphological uniform group, were globally widespread, and showed high virulence on tested white and Andean lupin accessions. Isolates belonging to the other five genetic groups were mostly found locally and showed distinct virulence patterns. Two highly virulent strains were shown to overcome resistance of advanced white lupin breeding material. This stresses the need to be careful with international seed transports in order to prevent spread of currently confined but potentially highly virulent strains. This study improves our understanding of the diversity, phylogeography and pathogenicity of a member of one of the world’s top 10 plant pathogen genera, providing valuable information for breeding programs and future disease management.

scholarly journals Breeding for Highly Fertile Isolates of Nectria haematococca MPVI that are Highly Virulent on Pea and In Planta Selection for Virulent Recombinants

2001 ◽  
Vol 91 (1) ◽  
pp. 92-101 ◽  
Author(s):  
Deanna L. Funnell ◽  
Patty S. Matthews ◽  
Hans D. VanEtten
Keyword(s):  
Mating Type ◽  
Low Fertility ◽  
Female Sterility ◽  
Polymorphism Analysis ◽  
Broad Host Range ◽  
High Fertility ◽  
In Planta ◽  
Nectria Haematococca ◽  
High Virulence ◽  
Highly Virulent

The heterothallic ascomycete Nectria haematococca mating population VI (anamorph Fusarium solani) is a broad host range pathogen. Field isolates of this fungus that are pathogenic on pea tend to be female sterile, of low fertility, and the same mating type (MAT-1), whereas female fertile isolates of either mating type that are highly fertile tend to be nonpathogenic on this plant. To facilitate genetic analysis of traits that may be important in the ability of N. haematococca to parasitize peas, a breeding project was undertaken to produce hermaphroditic isolates of each mating type that are highly fertile and highly virulent on peas. Although the association of high virulence on peas with female sterility and the MAT-1 mating type was not completely broken, isolates with high fertility and high virulence on peas were bred within two generations. Highly virulent progeny were also isolated by an alternative method in which pea plants were inoculated with a mixture of ascospores from a cross between two moderately virulent parents. Whereas all ascospores isolated without selection in planta had lower virulence than the parents, many isolates recovered from diseased tissue were more virulent than the parental isolates. Some of the recovered isolates were shown by restriction fragment length polymorphism analysis to be genetic recombinants of the parents, demonstrating that the pea tissue selected virulent recombinants. All highly virulent isolates tested had the ability to detoxify the pea phytoalexin pisatin, again showing a link between this trait and pathogenicity on the pea.

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