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PubMed1999

Mycobacterium tuberculosis CDC1551 induces a more vigorous host response in vivo and in vitro, but is not more virulent than other clinical isolates.

Mycobacterium tuberculosis CDC1551, a clinical isolate reported to be hypervirulent and to grow faster than other isolates, was compared with two other clinical isolates (HN60 and HN878) and two laboratory strains (H37Rv and Erdman). The initial (1-14 days) growth of CDC1551, HN60, HN878, and H37Rv was similar in the lungs of aerosol-infected mice, but growth of Erdman was slower. Thereafter, the growth rate of CDC1551 decreased relative to the other strains which continued to grow at comparable rates up to day 21. In the lungs of CDC1551-infected mice, small well-organized granulomas with high levels of TNF-alpha, IL-6, IL-10, IL-12, and IFN-gamma mRNA were apparent sooner than in lungs of mice infected with the other strains. CDC1551-infected mice survived significantly longer. These findings were confirmed in vitro. The growth rates of H37Rv and CDC1551 in human monocytes were the same, but higher levels of TNF-alpha, IL-10, IL-6, and IL-12 were induced in monocytes after infection with CDC1551 or by exposure of monocytes to lipid fractions from CDC1551. CD14 expression on the surface of the monocytes was up-regulated to a greater extent by exposure to the lipids of CDC1551. Thus, CDC1551 is not more virulent than other M. tuberculosis isolates in terms of growth in vivo and in vitro, but it induces a more rapid and robust host response.

Aerosols↗

PubMed1999

[Insertional mutagenesis of Arabidopsis thaliana: increase of germinating seeds transformation efficiency after sonication].

An efficient procedure of transforming Arabidopsis thaliana germinating seeds was elaborated on the basis of the method of Feldmann and Marks. The procedure involves microdamaging T1 seeds by sonication before culturing with a vector Agrobacterium strain and yields more than 1% T2 transformants. Germinating seeds were transformed with Agrobacterium timefaciens hypervirulent strain A281 carrying plasmid pLD3 derived from pBI121. A collection of 54 A. thaliana T2 transformants was obtained; some of them showed marked morphological alterations. The transgenic nature of plants that acquired resistance to a marker antibiotic was confirmed histochemically and by PCR amplification of a T-DNA region.

Arabidopsis↗

PubMed2002

MLEE and PFGE characterization of Neisseria meningitidis serogroup C and B isolated in the Slovak Republic in 1998.

In the Slovak Republic the incidence and mortality of invasive meningococcal disease increased after 1995 when the new meningococcal clone of Neisseria meningitidis C:2a:P1.2,P1.5, ET-1.5/37 emerged. The new clone spread between 1995 and 1998 throughout the whole country. Morbidity of invasive meningococcal disease was 1.6/100,000 of the population and fatality reached the highest level of 23% in the Slovak Republic in 1998. The new clone caused a new emergent epidemiological and clinical situation. The occurrence of invasive meningococcal disease caused by this clone has continually risen since 1995. In 1998 72% of all diseases in Slovakia were caused by serogroup C. The emerging clone C:2a:Pl.2,P1.5 represented 74% of the serogroup C isolates. Clonality and genetic diversity of 15 selected meningococcal strains causing invasive meningococcal disease was compared by multilocus enzyme electrophoresis (MLEE) and DNA macrorestriction analysis by pulsed-field gel electrophoresis (PFGE). The strains of serogroup C and B were isolated in all regions of Slovakia in 1998. The majority of isolates belong to hypervirulent clone ET-15 as determined by MLEE. By PFGE a higher degree of diversity was observed.

Adolescent↗

PubMed2003

[The Alkhurma virus (family Flaviviridae, genus Flavivirus): an emerging pathogen responsible for hemorrhage fever in the Middle East].

To date tick-borne flaviviruses causing hemorrhagic fevers in humans have been isolated in Siberia (Omsk hemorrhagic fever virus), India (Kyasanur Forest disease virus), and Saudi Arabia (Akhurma virus). Because of their potential use as biological weapons for bioterrorism, these 3 viruses require level 4 biosafety handling facilities and have been listed as hypervirulent pathogens by the Center for Disease Control and Prevention. Alkhurma virus was isolated in 1995 from patients with hemorrhagic fever in Saudi Arabia. Current evidence suggests that transmission to humans can occur either transcutaneously either by contamination of a skin wound with the blood of an infected vertebrate or bites of an infected tick or orally by drinking unpasteurized contaminated milk. To date a total of 24 symptomatic human cases have been recorded with a mortality rate at 25% (6/24). Pauci-symptomatic or asymptomatic cases are likely but epidemiologic data are currently unavailable. The complete coding sequence of the prototype strain of Alkhurma virus was determined and published in 2001 based on international research project involving investigators from France, Great Britain, and Saudi Arabia. Phylogenetic studies demonstrate that closest known relative of Alkhurma virus is Kyasanur Forest disease virus and that both viruses share a common ancestor. Genetic analysis of several human strains sequentially isolated over a 5-year period showed a very low diversity. This finding has important potential implications for diagnosis and vaccination.

Animals↗

PubMed2004

Surveillance of invasive meningococcal disease in the Czech Republic.

Routine notification of invasive meningococcal disease has a long tradition in the Czech Republic: mortality data are available from 1921 and morbidity data from 1943. The collection of Neisseria meningitidis strains kept in the NRL for Meningococcal Infections in Prague dates from 1970 onwards, and represents more than 3500 strains isolated from invasive disease and their contacts, from healthy carriers and from respiratory infection. Analysis of these strains showed that the Czech meningococcal population is different from that seen in western Europe. In 1993, the incidence serogroup C meningococcal disease increased and was associated with the emergence of the hypervirulent complex Neisseria meningitidis C, ST-11, ET-15/37, and caused an increase in the incidence of invasive meningococcal disease which peaked in 1995 (2.2/100,000). A vaccination strategy targeting the part of the population at highest risk of invasive meningococcal disease was adopted in the country.

Czech Republic↗

PubMed2004

Agrobacterium-mediated transformation of polyploid cereals. The efficiency of selection and transgene expression in wheat.

Three combinations of Agrobacterium tumefaciens strains and vectors were used in the transformation of selected Polish wheat cultivars. The combinations were: two hypervirulent strains, AGL1, containing the pDM805 binary plasmid, and EHA101, containing pGAH; and the common Agro strain LBA4404, harboring the super-binary pTOK233 vector. pDM805 contained bar under the control of Ubi1 promoter, pGAH had nptII under nos, and pTOK233 had hpt under 35S. Additionally, pDM805 and pTOK233 carried the gus reporter gene under the Act1 promoter or 35S promoter, respectively. The highest selection rate was 12.6% and was obtained with EHA101(pGAH) on a kanamycin-containing medium. Sixty-five of the plants grown on that medium were PCR positive. The second best combination was LBA4404(pTOK233) and kanamycin selection, which gave an average transformation rate of 2.3%. Phosphinothricin selection gave 1.0% transformation efficiency, while hygromycin, depending on the strain/vector used, gave from 0.2 to 0.4%. PCR tests in T1 revealed that 67% of the lines showed a 3:1 segregation ratio, and 11% a 15:1 ratio, while in 22%, segregation was non-Mendelian. The high number of T0 transgenic plants containing one copy of the transgene was confirmed via Southern blot analysis. Kanamycin resistance in the T1 generation was very low; in some lines, all the progeny were kanamycin sensitive. GUS expression, only tested in young T1 plants, was in agreement with Mendelian segregation in three out of the twelve tested. The factors influencing the efficiency of selection and transgene expression are discussed in this paper.

Agrobacterium tumefaciens↗

PubMedDate not supplied

[H5N1: vaccine solutions for humans and other animals].

The hypervirulence of H5N1 influenza virus makes it impossible to produce a vaccine traditionally (with egg embryos), but there are alternative solutions. A live recombinant fowl-pox H5 virus is used for avian pathology. An inactivated H5N2 adjuvant vaccine is rendered immunogenic by using hemagglutinin H5 (DIVA technique). Disease prevention strategies differ between European and Asian countries. WHO has opted for a recombinant vaccine based on a non pathogenic virus (PR8) to which modified H5 and N1 from a pandemic virus are grafted The poor immunogenicity of this vaccine will require the use of large doses and immunostimulants. A live vaccine based on an adenovirus coupled to the H5 gene was recently developed. Finally, Chinese authors are examining the preventive and curative potential of hyperimmune serum raised in animals.

Animals↗