Leishmania challenge model
Inventors
Fischer, Laurent • Kamahwi, Shaden • Valenzuela, Jesus • Suau, Hamide Aslan
Assignees
Boehringer Ingelheim Animal Health USA Inc • US Department of Health and Human Services
Publication Number
US-8906358-B2
Publication Date
2014-12-09
Expiration Date
2031-11-15
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Abstract
The present invention provides a method for effectively and reproducibly infecting canines with Leishmania infantum using sand flies to vector the parasite. The inventive method comprises several steps, including ensuring canines are naïve to Leishmania, infecting the canines using bites of Leishmania-infected sand fly bites, and evaluating successful transmission of the Leishmania parasites.
Core Innovation
The present invention provides a method for effectively and reproducibly infecting canines with Leishmania infantum using sand flies to vector the parasite. The method involves testing canines to ensure they are naive to Leishmania and sand fly salivary proteins, transmitting the parasite through multiple bites of Leishmania-infected sand flies, and scoring the sand flies post-transmission to verify successful parasite transmission.
The invention addresses the problem that existing models of infection often rely on unnatural methods such as intravenous or intracardiac injections of a large number of parasites, which do not reflect the natural mode of transmission through sand fly bites. Prior attempts to infect dogs using infected sand flies resulted in physiological changes but not clinical disease, highlighting the challenge in developing a reproducible, clinically relevant infection model that mimics natural transmission.
The invention’s method overcomes this challenge by using virulent, recently isolated Leishmania infantum strains from sick canines, ensuring sand flies have mature infections with a high parasite load and metacyclic forms, applying multiple transmissions at multiple sites to mimic field conditions, and selecting young naive canines. This creates a reproducible model that reflects the chronic and polymorphic nature of canine visceral leishmaniasis as observed in the field, providing a valuable tool for vaccine and therapeutic studies.
Claims Coverage
The claims include one independent method claim that covers the key inventive features related to infecting canine animals with Leishmania parasites using sand fly bites, along with supporting dependent claims that elaborate on various aspects of the method.
Method for infecting canines with Leishmania via infected sand fly bites
A method comprising steps of testing canines to confirm they are naive to Leishmania and sand fly salivary proteins; infecting vector sand flies with a virulent Leishmania isolate obtained from an infected canine; transmitting the Leishmania parasite to canines through bites from these infected sand flies; and quantifying parasite load per fly post transmission to verify successful infection.
Use of virulent Leishmania isolates in sand flies
Infecting sand flies with virulent Leishmania species isolates at passage 5 or lower, accomplished by feeding sand flies blood containing the Leishmania parasites to maintain parasite virulence for transmission.
Controlled number and quality of sand fly bites for transmission
Performing transmission using 10 to 50 infected sand fly bites, wherein the infected sand flies harbor at least 30,000 Leishmania parasites with 50% or more parasites being metacyclic forms for effective transmission.
Testing canines for previous exposure to sand fly salivary proteins and Leishmania-specific components
Ensuring canines are naive by testing for previous exposure to sand fly salivary peptides or proteins and presence of Leishmania-specific components or host-produced antibodies against these components.
Multiple bite sites to mimic natural infection conditions
Carrying out transmission at multiple sites on the canine's body to replicate field conditions of recurrent exposure to infected sand fly bites.
Comprehensive infection method modeling natural canine Leishmania infection
A method involving selection of young canines six months or younger, testing for naivety, infecting sand flies with virulent Leishmania isolates obtained from infected canines, monitoring infection progression in sand flies (including parasite number and metacyclic percentage), infecting flies 1-3 times weekly, transmission at multiple sites over multiple sessions, and scoring sand flies for feeding success and infection status to model natural infection.
The claims collectively cover a novel, reproducible method for infecting canines with Leishmania parasites through bites of virulently infected sand flies, with key features ensuring natural mode of transmission, parasite virulence maintenance, multiple transmission events, and confirmation of successful infection.
Stated Advantages
Provides a reproducible infection model that mimics natural transmission of Leishmania infantum in dogs via sand fly bites.
Enables evaluation of vaccine and therapeutic efficacy under natural infection conditions, enhancing study outcomes and reducing costs.
Reflects the chronicity and clinical manifestations of canine visceral leishmaniasis observed in endemic areas, including cutaneous and visceral signs.
Allows controlled, efficient, and effective infection with verification of parasite transmission through scoring of sand flies post-bite.
Documented Applications
Modeling natural canine Leishmania infantum infection for evaluating anti-Leishmania biologicals such as vaccines.
Evaluating anti-Leishmania pharmaceutics including antiparasitic and antiprotozoal drugs.
Studying disease progression and immune response in dogs to support development of vaccines and therapeutics for canine leishmaniasis.
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