Protein Signals - Week of December 29, 2025

Deep Dive - ImmuCell Abandons Re-Tain Mastitis Treatment After Second FDA Manufacturing Rejection

ImmuCell's decade-long effort to commercialize Re-Tain, a nisin-based mastitis treatment with anticipated zero-milk-discard labeling, ended with a second FDA Incomplete Letter citing persistent manufacturing deficiencies at a third-party contract manufacturer. The company will book a $2.3 million impairment against $15.5 million in capitalized development costs and redirect resources toward expanding its First Defense scours prevention franchise, including a 50% increase in US field sales staff. This outcome validates the structural advantage of large animal health companies with in-house manufacturing infrastructure over small-cap innovators dependent on CMO partners for aseptic fill-finish operations.

FDA's conditional approval of Merck's Exzolt Cattle-CA1 under expedited Priority Zoonotic Animal Drug designation provides US ranchers with a second treatment option as New World screwworm cases in Mexico exceed 138,000 animals less than 70 miles from Texas. The topical pour-on formulation using fluralaner, an isoxazoline mechanism novel to cattle, offers easier mass deployment than Zoetis's injectable Dectomax-CA1 approved in September, but carries a 98-day slaughter withdrawal versus 35 days for the competitor product. This tradeoff will segment adoption between operations prioritizing application convenience and those needing faster market return during supply disruptions.

The crisis has exposed systemic biosecurity preparedness gaps: prior to September 2025, no FDA-approved screwworm treatments existed despite the pest's known catastrophic potential. USDA's $100 million emergency response, including a new sterile fly production facility in Texas targeting 300 million flies per week, represents reactive rather than strategic investment. The US-Mexico cattle border closure since July 2025 has disrupted annual imports exceeding one million head, with Texas estimating $1.9 billion in annual economic impact if screwworm establishes domestically.

Dutch animal health firm AHV International secured European patent protection for its Quorum Sensing Inhibition technology, which uses plant-derived extracts to disrupt bacterial communication and biofilm formation without antibiotics or withdrawal periods. The mechanism targets autoinducer signaling molecules that bacteria use to coordinate collective behavior, degrading protective biofilms and exposing pathogens to natural immune responses. Field data across 2,700 dairy cows demonstrated 14% reduction in udder health issues and 19.8% fewer replacements, validating commercial efficacy in the company's target market of 25 countries and 10,000 farmer relationships.

The patent positions AHV as a differentiated acquisition target in a consolidating antibiotic alternatives sector projected to reach $6.5 billion by 2035. Recent transactions including PAI Partners' acquisition of Innovad Group and Kemin's purchase of BioDose signal active strategic interest in specialized feed additive technologies. AHV's IP protection covers methods rather than just products across ruminants, swine, poultry, and aquaculture, creating defensible value against generic phytogenic competitors as regulatory pressure against antibiotic use intensifies globally.

The Epitopix LLC (Vaxxinova US) patent infringement case against Zoetis entered 2025 with a January court opinion as the companies dispute whether Zoetis exceeded limited commercialization rights for Siderophore Receptor Protein vaccine technology after their 2012 agreement terminated in January 2021. Products allegedly at issue include Zoetis's One Shot cattle vaccines and Poulvac E. coli poultry vaccines, representing meaningful revenue streams within Zoetis's biologics portfolio. Vaxxinova holds over 150 global patents covering SRP compositions, establishing substantial leverage if infringement is proven. The case arrives as Zoetis pivots toward vaccines and biologics, having divested its medicated feed additive portfolio to Phibro for $350 million. 

The Federal Register notice requesting comments on New Swine Inspection System information collection renewal is administratively routine, but arrives as the administration accelerates NSIS expansion with 17-18 plants operating under the program, 4 pending applications, and 6 facilities testing higher line speeds under time-limited trials. A separate August 2025 proposed rule would eliminate mandatory lymph node incision and viscera palpation while reducing FSIS inspector staffing, generating estimated annual savings of $2-8 million for the agency and $15-25 million for industry. Secretary Rollins has signaled intent to make permanent the increased line speeds currently operating under temporary authorization.

The policy trajectory favors packers despite contested safety data and a 2021 federal court ruling that vacated unlimited line speed provisions for failure to consider worker impacts. UFCW, representing workers handling 71% of US hog slaughter, cites injury rates 2.4 times other industries, while a 2025 UCSF study associated piece-rate compensation rather than line speed with injury risk. Plants representing the majority of US pork supply were projected for potential NSIS adoption, concentrating efficiency gains among large integrated processors while the fundamental worker safety debate remains unresolved through administrative, judicial, and now legislative channels.