Frequently Asked Questions

What is the standard panel of tissues required by regulators for AAV biodistribution?

Regulatory expectations typically include the target tissue(s), gonads (testes and ovaries), and major organs with known potential for vector accumulation or toxicity. This often involves the brain, heart, lung, liver, kidney, and spleen. The final list is tailored based on the specific AAV serotype, route of administration, and target indication.

How do you ensure qPCR assay specificity for the vector genome versus endogenous sequences?

Assay specificity is achieved through rigorous in-silico and wet-lab validation. Primers and probes are designed to target unique sequences within the vector construct, such as the transgene cassette or ITRs, that have no significant homology with the host genome of the relevant species. Specificity is confirmed by testing against gDNA from naive animals.

What is the typical sensitivity of your qPCR assays in complex matrices?

Our phase-appropriate validated qPCR assays are designed to achieve high sensitivity, meeting or surpassing recommendations from regulatory agencies, enabling precise quantification of vector genome copies (VGC) per microgram of genomic DNA. This performance is maintained across challenging matrices, including CNS and fibrotic tissues, to generate reliable data for IND-enabling toxicology studies.

Additional Insights

Precise biodistribution data is a core component for building a compelling regulatory submission for advanced therapeutics and complex biologics. Applying decades of experience and proven intelligence in bioanalysis supports the accurate quantification of vector genome copies in target and off-target tissues, providing clear data to inform risk assessment and clinical translation. Quantitative PCR (qPCR) remains the definitive method for these assessments in GLP-compliant environments.

A tailored preclinical strategy is required for every novel therapeutic. Standard testing templates are insufficient for characterizing the unique tropisms of clinically validated capsids like AAV8 and AAV9, or for novel engineered vectors. Each program demands a data-driven approach to biodistribution analysis, designed specifically for the asset modality and its intended clinical application.

The design and validation of qPCR assays for GLP-compliant programs must be meticulous. This includes:

• Targeting stable, unique regions of the vector genome.
• Confirming specificity and absence of cross-reactivity with host gDNA.
• Establishing a validated quantification range with high precision and accuracy.
• Developing all assays in a phase-appropriate manner compliant with GxP guidelines.

Published research underscores the direct link between capsid design and biodistribution outcomes. Engineering AAV capsids can significantly alter tissue tropism, and preclinical safety evaluations must account for potential cross-species differences in vector avidity between preclinical models and humans [PMID: 39001819]. Biodistribution assessments are also used to confirm the efficacy of strategies intended to mitigate off-target vector accumulation, such as those designed to limit peripheral exposure following CNS-targeted delivery [PMID: 36320416].

This service is a component of our comprehensive Bioanalytical Services offering, designed to guide therapeutic programs from discovery through clinical development.