35 results about "Avirulent strain" patented technology

A provided multiple fluorescence PCR detection kit for clostridium difficile toxin genes mainly comprises specific primers, probes and a PCR reaction reagent, and the specific primers and the probes respectively consist of specific primers and probes of clostridium difficile toxin A (tcdA), toxin B (tcdB), binary toxin A (cdtA) and binary toxinB (cdtB). The beneficial effects of the invention comprise: the fast, sensitive and specific multiple fluorescence PCR detection kit and a detection method are provided for the clostridium difficile toxin genes, and a foundation is provided for distinguishing between toxigenic strains and avirulent strains of clostridium difficile, and early diagnosis on infection of clostridium difficile.

The invention discloses an Aspergillus flavus avirulent strain and an application of the Aspergillus flavus avirulent strain in controlling pollution of Aspergillus flavus. In the avirulent strain, the Aspergillus flavus does not express pathogenesis related genes aflash1. The strain is non-toxic, does not produce sclerotium, produces a large quantity of spores in a culture medium and a small quantity of spores on an organism and has low pathogenicity. On the basis of the characteristics of the strain, the invention further discloses a method for controlling pollution of the Aspergillus flavus by use of the strain. More specifically, the method comprises steps as follows: by use of the characteristics that the Aspergillus flavus strain is non-toxic, does not produce sclerotium, produces a large quantity of spores in a culture medium and a small quantity of spores on an organism and has low pathogenicity, limited ecological niches are scrambled in main peanut producing areas and other susceptible areas of Aspergillus flavus through the strain and wild toxic-producing Aspergillus flavus strains, the density of the wild toxic-producing Aspergillus flavus strains is effectively reduced, and Aspergillus flavus infection to crops, Aspergillus flavus toxin pollution and aspergillosis infection caused by Aspergillus flavus toxin pollution are effectively controlled and reduced.

The invention discloses an LAMP assay kit for identifying virulent and avirulent strains of mycoplasma gallisepticum. A primer group A provided by the LAMP assay kit consists of a primer group a and a primer group b; the primer group a consists of a primer 1 and a primer 2; the primer group b consists of a primer 3 and a primer 4; and the nucleotide sequences of the primer 1, the primer 2, the primer 3 and the primer 4 are sequence 1, sequence 2, sequence 3 and sequence 4 sequentially in a sequence table. An experiment for the LAMP assay kit proves that the primers and the method only need anordinary water bath rather other an expensive PCR (Polymerase Chain Reaction) instrument but have higher sensitivity than PCR assay, moreover, a result does not need to be observed by way of gel electrophoresis, and the LAMP assay kit is easy and rapid to operate, and is particularly suitable for field assay in grass roots.

Chimeric replicons of North American Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) containing the 5′ sequence of an avirulent strain of PRRSV and a 3′ sequence of a virulent strain of PRRSV are provided. Further provided is a method of producing attenuated PRRSV from the chimeric replicon. Also provided are compositions containing the replicon or attenuated virus. Vaccines and a method of vaccinating pigs against PRRSV are also provided.

The present invention is directed to processes and compositions for protecting host animals (e.g., chickens) from exposure to virulent infectious bronchitis virus. In ovo administration of live, avirulent strains of IB at appropriate dosage levels on a per egg basis provides an effective and efficient vaccination having acceptable safety and efficacy features.

The invention relates to a nontoxic ST28 streptococcus suis and an application thereof, and belongs to the biotechnology field. A tonsil sample of a healthy slaughter pig is collected; after bacteria enrichment processing, bacteria DNA (deoxyribonucleic acid) is extracted; a cps2j gene is identified by polymerase chain reaction; then, pure culture bacteria can be obtained by bacteria plate separation; the pure culture bacteria is subjected to gram stain, serum agglutination, polymerase chain reaction and multilocus sequence typing to determine and separate type-2 bacterial strain of the streptococcus suis and a sequence type thereof; animal experiments of a Balb/c mice, a New Zealand rabbit and a Landrace piglet prove that the bacteria HA0609 is a nontoxic bacterial strain; after the bacteria is subjected to intramuscular injection into the New Zealand rabbit for one time and is subjected to intraperitoneal injection into a CD1 mice for two times, certain immunocompetence can be provided for an immunized animal, and analysis on a HA0609 immune protection antigen can be used for developing streptococcus suis disease subunit vaccine.

The invention relates to the field of wheat disease resistance, and specifically relates to a BFR protein associated with resistance of wheat to powdery mildew as well as a coding gene and applicationthereof. The BFR protein associated with resistance of wheat to powdery mildew has an amino acid sequence as shown in sequence 7, or a sequence constructed by replacing one or more amino acids in theamino acid sequence shown in sequence 7. Expression of the BFR protein in wheat leaves is reduced by adopting a virus-induced gene silencing technology and a CRISPR/Cas9 gene editing technology so asto have reaction type of infection of a powdery-mildew-resistant wheat variety, xiao-bai-dong (Triticum aestivum L.), on an avirulent strain E18 changed from grade 0-1 to grade 3-4. Over-expression of the BFR gene in wheat leaves is allowed by adopting biolistic transformation; and thus, pathogen spore germination of a virulent strain E18 on leaves of the wheat variety Kelong-199 is significantlyinhibited.

The invention discloses a method for expanding reproduction of ralstonia solanacearium bacteriophage. An avirulent ralstonia solanacearium strain RSsw326-2 disclosed by the invention is preserved in CCTCC (China Center for Type Culture Collection) and has the preservation number of CCTCC NO. M 2018197. The avirulent ralstonia solanacearium disclosed by the invention is ralstonia solanacearium obtained by separating from naturally infected tobacco plants; by subculture, dissociant is obtained; by pathogenicity determination, the dissociant losing pathogenicity for tobacco seedlings is the ralstonia solanacearium avirulent strain; when the avirulent ralstonia solanacearium avirulent is utilized to reproduce the ralstonia solanacearium bacteriophage, the ralstonia solanacearium bacteriophagewith a high titer can be obtained. The method is expected to be used as a carrier for greatly expanding reproduction of the bacteriophage in the ralstonia solanacearium bacteriophage biological pesticide development so as to avoid secondary damage to prevention and control objects due to the toxicity of a host strain.

Chimeric replicons of North American Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) containing the 5' sequence of an avirulent strain of PRRSV and a 3' sequence of a virulent strain of PRRSV are provided. Further provided is a method of producing attenuated PRRSVfrom the chimeric replicon. Also provided are compositions containing the replicon or attenuated virus. Vaccines and a method of vaccinating pigs against PRRSV are also provided.

The present invention relates to nucleic acids encoding B. mallei and B. pseudomallei AHL synthases and LuxR transcriptional regulators, and methods for use, as well as describes the construction, characterization and use of avirulent strains of B. mallei and methods of use.

The invention provides live attenuated avirulent strains of Francisella tularensis, as well as methods for their preparation and use in protecting a mammal against infection with F. tularensis and against tularemia.

Belonging to the field of biotechnology, the invention discloses a specific molecular marker primer for identification of phytopthora sojae avirulence gene PsAvr1k and a method. The specific molecular marker primer pair has an upstream primer nucleotide sequence shown as SEQ ID No.3 and a downstream primer nucleotide sequence shown as SEQ ID No.4. Through the molecular marker PCR amplification by means of the molecular marker can rapidly and efficiently detect whether a field phytopthora sojae strain is a PsAvr1k virulent strain or avirulent strain. The research not only can be used for studying the distribution of PsAvr1k avirulence gene in the field, but also can reveal the pathotype differentiation variation characteristics of the phytopthora sojae PsAvr1k, and provides the basis for making of a resistant variety selection strategy.