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The truth about the 2021 anthrax attacks: How did the Ans strain become a weapon of terror?
Of the many strains of anthrax (Bacillus anthracis), the Ans strain is undoubtedly the most notorious. The strain's origins can be traced back to 1981, when a sample obtained in Texas shocked researchers and it subsequently became an unexpected symbol of bioterror. What was so special about the Ans strain that made it play such a significant role in the 2001 attacks?
The Ans strain is used as a tool for vaccine development and testing in the United States because of its pathogenicity.
The Ans strain was isolated from a dead cow in 1981 and was originally inconspicuous. However, the anthrax attacks in 2001 brought it into the spotlight. Since then, issues related to Ans strains have become an integral part of biosafety and public health.
Pathogenicity of Ans strains
The high pathogenicity of the Ans strain is due to the two special virulence plasmids it contains: pXO1 and pXO2. These plasmids help anthrax bacteria evade the host's immune system and carry out a deadly infection. The researchers found that strains lacking these plasmids lost their ability to cause disease, making Ans strains important in studying viral diseases.
The virulence of ans strains can be explained by the presence or absence of plasmids, and strains lacking one of these plasmids are generally considered to be attenuated.
In the United States, the Ans strain has become an important basis for vaccine development due to its strong pathogenicity. Although it is not significantly resistant to antibiotics, its variability complicates medical professionals' efforts to combat it.
Antibiotic resistance
Ans strains have antibiotic susceptibility similar to most anthrax strains, and the mainstay of treatment is ciprofloxacin. Recent studies have shown that new fluoroquinolones, such as jaficofloxacin, have a significant effect on improving the survival rate of mice infected with the Ans strain.
Studies of the Ans strain have shown that it remains sensitive to commonly used antibiotics, which is crucial for treatment.
In contrast, the Stern strain serves as a standard comparison, and its lack of virulence makes it a unique reference point in biological research. This knowledge helps scientists understand the variation and responses between different strains.
Vaccine Development
To combat the threat of anthrax, scientists began developing vaccines based on attenuated strains. Some vaccines use weakened strains, such as the Stern strain, to elicit an immune response. However, no effective vaccine has been successfully developed for the Ans strain, which makes the research task of preventing anthrax difficult.
Vaccine development for the Ans strain is still ongoing, and scientists are looking for more ways to improve the effectiveness of the vaccine.
Another type of vaccine targets toxin proteins, but their protective efficacy is relatively low compared to vaccines that target live spores. Currently, the only anthrax vaccine approved for human use in the United States is the Anthrax Vaccine Adsorbent (AVA). The effectiveness of this vaccine is not consistent in different animal models, which shows the challenges of vaccine development.
Strain tracking technology
By tracking single nucleotide polymorphisms (SNPs) unique to anthrax strains, scientists were able to develop more effective diagnostic tests to track anthrax outbreaks. Through these SNPs, researchers can effectively identify samples related to the Ans strain, and these markers are highly stable, reducing the probability of false positives during the detection process.
Stable genetic markers provide a feasible means to track anthrax outbreaks, which is critical for public health protection.
Taking all the above factors into consideration, the special nature of the Ans strain has made it a hot topic in biosafety research and has also triggered deep thinking about its potential terrorist uses. In the future, will scientists be able to find effective ways to prevent such serious biological threats?
