Bridging Discovery and Translational Science: Why Infectious Disease Programs Need Integrated In Vitro and In Vivo Models

Infectious disease drug development rarely fails because of a lack of promising ideas. More often, programs stall—or collapse entirely—at the transition between early discovery and translational validation. What works cleanly in a cell-based system doesn’t always translate to efficacy, safety, or durability in an animal model, and those disconnects can derail timelines, budgets, and regulatory confidence.

At Southern Research, infectious disease programs are intentionally designed to close that gap. By tightly integrating in vitro screening, in vivo validation, and downstream translational expertise, Southern Research helps sponsors make confident go/no-go decisions earlier—before risk compounds and resources are wasted.

The Discovery–Translation Gap in Infectious Disease Research

Many infectious disease programs begin with encouraging in vitro data: strong inhibition rates, clear IC₅₀ or EC₅₀ values, and apparent antiviral activity in cell-based assays. But once those same compounds are evaluated in animal models, results often diverge.

This disconnect isn’t unusual. Cell systems cannot fully replicate immune complexity, viral dynamics, tissue tropism, or host responses. A compound that appears potent in vitro may require impractically high doses in vivo, exhibit unexpected toxicity, or fail to demonstrate meaningful protection under challenge.

The transition from in vitro discovery to in vivo validation is therefore a critical inflection point—one that determines whether a program advances or stalls.

Designing In Vitro Assays That Predict In Vivo Outcomes

At Southern Research, in vitro screening is not treated as an isolated discovery step, but as the foundation for translational success.

Rather than relying solely on laboratory-adapted strains, Southern Research incorporates relevant and circulating viral strains whenever possible, aligning early data with real-world disease biology and regulatory expectations. Sponsors are increasingly asked by regulators to demonstrate activity across broader viral panels, especially when claims extend to respiratory or emerging pathogens.

Southern Research supports both pseudovirus systems and live infectious virus work, with a clear understanding of where each approach adds value. While pseudoviruses can accelerate early screening, infectious virus assays provide a more faithful readout of immunogenicity and therapeutic effect under true infection conditions—often yielding data that better predicts animal outcomes.

High-throughput cytopathic effect (CPE) assays play a central role in this strategy. Using 384-well formats, Southern Research can screen limited quantities of test article rapidly, generating IC₅₀, EC₅₀, and EC₉₀ values that allow sponsors to identify and prioritize the most promising candidates before moving into animals.

Just as importantly, early in vitro screening helps identify cytotoxicity risks, supporting animal welfare and preventing avoidable failures later in development.

Translating Discovery into Disease-Relevant In Vivo Models

When programs advance into in vivo evaluation, Southern Research offers one of the industry’s most comprehensive infectious disease capabilities. Studies are conducted across BSL-2 and BSL-3 environments using rodents and large animal NHP models, with GLP-regulated options available even in high-containment settings.

Disease-relevant endpoints are selected early and intentionally. Survival is not always the most meaningful measure—many viral infections are non-lethal. Instead, Southern Research evaluates protection against severe disease using clinically relevant parameters such as viral load, weight loss, lesion burden, respiratory function, fever, pathology, and comprehensive clinical scoring.

These endpoints allow sponsors to assess both prophylactic and therapeutic countermeasures, capturing how a test article performs before infection, after exposure, or during active disease. By designing endpoints that mirror clinical expectations, Southern Research strengthens the translational relevance of preclinical data.

Integration That Reduces Redundancy and Failure

What distinguishes Southern Research is not just the breadth of its models, but the way teams operate across them.

Virologists, immunologists, toxicologists, pathologists, and study directors collaborate across in vitro and in vivo phases, ensuring continuity in study design, data interpretation, and decision-making. When unexpected toxicity or insufficient efficacy emerges in animals, those insights can immediately inform compound optimization or program redirection—without the friction of cross-vendor handoffs.

This integration reduces redundant studies, shortens development cycles, and improves the quality of data packages moving toward IND-enabling work.

Mission-Ready for Emerging and Evolving Threats

Infectious disease development rarely follows a static playbook. New variants emerge, host-range shifts occur, and regulatory priorities change.

Southern Research operates with a mission-ready mindset—adapting established assays to new pathogens, acquiring emerging viral strains, and pivoting expertise toward the next medical threat, whether that’s a novel respiratory virus, avian influenza, poxvirus, dengue, or a future pandemic-scale challenge.

This adaptability is driven by experienced scientific staff with deep infectious disease expertise and a proven ability to translate established platforms into new applications rapidly.

A Translational Partner Across the Entire Pipeline

Southern Research supports infectious disease sponsors at every stage of development. Programs may begin with hit-to-lead discovery, advance into animal efficacy and safety studies, transition into GLP-regulated IND-enabling work, and continue into GCLP clinical trial sample analysis—all within a single integrated framework.

Assays developed in preclinical phases are validated under GLP and seamlessly transitioned into clinical settings, supported by unified data systems and technical teams who understand the full context of the program.

This continuity positions Southern Research not as a single-study CRO, but as a long-term translational partner aligned with regulatory expectations and sponsor timelines.

One Piece of Advice for Infectious Disease Sponsors

For sponsors designing infectious disease programs, the most important step is early planning.

Engaging experienced scientific and project management teams early—before pivotal decisions are locked in—helps clarify regulatory expectations, define critical endpoints, and build a coherent path to the FDA. Early discussions allow programs to be scoped realistically, budgets to be aligned with regulatory requirements, and timelines to be built backward from submission goals.

In infectious disease research, uncertainty is inevitable. What matters is working with a partner equipped to anticipate challenges, adapt to change, and guide programs from discovery through translation with confidence.