Why does intradermal injection matter for antigen delivery in vaccine studies?

Intradermal injection targets antigen-presenting cells in the dermis, enhancing immune priming and enabling measurable local responses such as papule formation for assay validation.

How does radiation attenuation of sporozoites support immune response evaluation?

Radiation attenuation renders sporozoites non-infectious while preserving antigenic structure, allowing safe assessment of immune activation without pathogenicity.

What does papule formation indicate following dermal antigen injection?

A visible papule confirms successful intradermal delivery and correlates with localized immune activation, serving as a procedural success metric.

Why are multiple injection sites used in both ears during immunization?

Multiple bilateral injections increase antigen exposure and immune cell recruitment, improving the robustness and reproducibility of the immune response readout.

How does post-injection recovery monitoring affect data quality in immunization studies?

Monitoring recovery ensures animal welfare and reduces stress-induced immunological variability, supporting consistent and reliable immune response measurements.

Intradermal Immunization with Live Attenuated Sporozoites in a Mouse Model

JoVE Encyclopedia of Experiments

Immunology

0 views • 2:19 min • July 8th, 2025

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Begin with an anesthetized mouse under a stereomicroscope, with the underside of one of the mouse's ears fixed on the stage via adhesive tape.

The eyes are coated with an ointment to prevent them from drying.

Bring a syringe loaded with the sporozoite stage of Plasmodium, a malarial parasite. The live sporozoites are radiation-attenuated to render them non-infectious.

Using the stereomicroscope, inject into the top side of the ear, penetrating the outermost epidermis layer and releasing the sporozoites into the dermis.

Keep the needle in place briefly to prevent backflow of the injected suspension before removing it.

A visible swelling at the injection site, termed a papule, confirms a successful injection.

Perform multiple injections into the same ear.

Release the injected ear and repeat the injections into the other ear.

Post-injection, allow the mouse to recover.

The injected sporozoites trigger an immune response, priming the immune system against the parasite.

Before injecting the sporozoites, confirm the proper level of sedation of the experimental animal by toe pinch, and apply eye ointment to prevent corneal drying. Then, working quickly, use clear tape to gently fix the ventral side of the ear pinna under a stereomicroscope, and load a 10-microliter syringe equipped with a 35-gauge needle with 0.6 microliters of resuspended parasites.

Next, carefully insert the needle, bevel side up, beneath the epidermis on the dorsal side of the ear, and inject 0.15 microliters of sporozoites into the site. A characteristic papule will be observed at the injection site. After injecting the dermis three more times as just demonstrated, carefully remove the tape and monitor the mouse until it is fully recovered.