Developing Tadpole Xenopus laevis as a Comparative Animal Model to Study Mycobacterium abscessus Pathogenicity

Area of Science:

• Microbiology
• Infectious Diseases
• Animal Models

Background:

• Mycobacterium abscessus (Mab) is a growing cause of human infections.
• Mab exhibits two morphotypes, smooth (S) and rough (R), with differing pathogenic potential.
• Existing models like mice and zebrafish have limitations for studying chronic Mab infections.

Purpose of the Study:

• To evaluate Xenopus laevis tadpoles as an alternative animal model for Mab pathogenesis.
• To compare the in vivo behavior of S and R Mab morphotypes in tadpoles.
• To investigate persistent Mab infection and host immune responses.

Main Methods:

• Intraperitoneal (IP) and intracardiac (IC) inoculation of S and R Mab morphotypes into Xenopus laevis tadpoles.
• Monitoring of bacterial dissemination, persistence, and mortality over 40 days.
• Comparative analysis of Mab morphotype behavior in the tadpole model.

Main Results:

• Mab disseminated to tadpole tissues, including liver and lungs, persisting for up to 40 days.
• The R morphotype showed greater persistence with higher bacterial loads compared to the S morphotype.
• IC inoculation with S Mab resulted in higher mortality than with R Mab.

Conclusions:

• Xenopus laevis tadpoles serve as a viable complementary model for studying persistent Mab infections.
• The tadpole model facilitates comparative studies of Mab morphotype pathogenesis and host resistance.
• This model offers insights into T cell involvement and pulmonary infections, overcoming limitations of previous models.