Bulk Classical Swine Fever Vaccine Veterinary Grade API for lyophilised parenteral presentation is received as a clarified virus harvest from PK-15 or STE cell culture, filtered through 0.45 µm and 0.22 µm membrane systems, and stabilised with a combination of sucrose, gelatin, and peptone. The approval-linked master seed and working seed lot documentation is maintained under the principles of WOAH Terrestrial Manual Chapter 3.9.3. Before freeze-drying, the antigen concentrate is adjusted to a total solids content of 4% to 8% w/v and filled aseptically into 6R or 10R tubular glass vials conforming to ISO 8362-1:2018; filling is executed in an ISO 5 zone according to ISO 14644-1:2015 and ISO 13408-1:2008. The freezing programme reduces product temperature below the maximal freeze-concentration glass transition temperature of the frozen matrix, typically −35 °C to −45 °C, before primary drying at a shelf temperature of −15 °C to −10 °C and a chamber pressure of 80 µbar to 150 µbar. Primary drying endpoint is determined by comparative pressure measurement or Pirani-capacitance manometer crossover; excessively aggressive primary drying produces collapse or melt-back in the plug and reduces recoverable virus titre. Secondary drying is run at +20 °C to +25 °C until Karl Fischer titration per Ph. Eur. 2.5.32 shows residual moisture not more than 2.5%. Batches exceeding 2.5% residual moisture display accelerated titre loss after stopper closure, particularly when the headspace oxygen content is not reduced to 2% or less by nitrogen flushing. The terminal lyophilised powder is reconstituted in sterile isotonic diluent containing 0.85% sodium chloride and 0.1% polysorbate 80, then administered by intramuscular injection at a volume of 1.0 mL per animal. Sterility testing is performed by membrane filtration per Ph. Eur. 2.6.1, and the aseptic processing release is aligned with 21 CFR 610.12. Published data for this specific configuration under commercial CSFV lyophilised injection is limited to manufacturer-specific monographs; the process parameters above are typical for stabilised live veterinary viral lyophilisates and must be verified against the specific API lot and freeze-drier shelf geometry.

What Controls Droplet Size Distribution in Adjuvanted Injectable Emulsions Containing CSFV Antigen?

Adjuvanted injectable emulsions are prepared when the biological API is formulated as an inactivated or subunit CSFV antigen concentrate in a water-in-oil-in-water or oil-in-water system. The aqueous antigen phase is first blended at 2% to 10% w/w into a buffered isotonic matrix, then introduced into a jacketed formulation vessel maintained at 4 °C to 8 °C. A rotor-stator homogeniser with tip speed 10 m/s to 25 m/s is used for primary emulsification; the shear rate controls the median droplet size, and therefore syringeability, short-term physical stability, and adjuvant depot formation. Droplet size distribution is measured by laser diffraction according to ISO 13320:2020, with Dv50 typically held between 0.8 µm and 2.0 µm and Dv90 not more than 5.0 µm. Droplets exceeding 5.0 µm increase creaming and phase separation in the final container, while droplets below 0.5 µm may expose excessive oil-water interface area and increase antigen adsorption loss. Viscosity is measured by rotational viscometry per Ph. Eur. 2.2.10 at 25 °C; target viscosity for syringability is normally 20 mPa·s to 80 mPa·s, but the final range depends on needle gauge and animal handling conditions. The terminal injectable emulsion is filled under aseptic conditions, tested for sterility according to Ph. Eur. 2.6.1, and endotoxin by Ph. Eur. 2.6.14 with a limit of not more than 0.5 EU per dose. Bacterial endotoxin contamination above this threshold can trigger localized injection-site reactions and is screened on bulk antigen concentrate before emulsification. The process is not compatible with cationic amine-based preservatives because the lipid-enveloped CSFV particle loses integrity through envelope disruption and protein aggregation. Table 1 summarises critical quality attributes for this injectable emulsion configuration.

Compressed Tablet Cores Prepared from Lyophilised CSFV Antigen

Investigational oral bait vaccination programmes for wild boar have evaluated lyophilised CSFV antigen compressed into tablet cores or bait matrices intended for mucosal exposure rather than systemic absorption. The limiting unit operation is direct compression, because the live virus is shear-labile and the tabletting pressure applied to the granulation bed can reduce recoverable titre. A rotary tablet press with 8.0 mm flat-faced bevel-edge tooling is typically run at low compression force—5 kN to 10 kN—and at reduced turret speed to limit dwell time and heat generation. Tablet hardness is intentionally kept low, often 20 N to 40 N, and the target is bait integrity rather than conventional pharmaceutical hardness. Excipients are selected from directly compressible mannitol, microcrystalline cellulose, and a buffering salt such as calcium carbonate to maintain local pH above 6.5 during dissolution. Wet granulation is incompatible with live CSFV antigen because water and subsequent drying above 35 °C accelerate titre loss; if granulation is unavoidable, dry granulation by roller compaction at roll pressure not more than 20 kN and sieve milling through a 1.0 mm screen is preferred. Enteric protection, if required, cannot be applied as an aqueous acrylic dispersion because residual moisture and drying temperature inactivate the virus; non-aqueous coating systems must be validated for residual solvents per Ph. Eur. 5.4. A disintegration test per Ph. Eur. 2.9.1 is of limited relevance because the intended biodistribution is oropharyngeal or tonsillar contact; the more meaningful release test is virus titration after simulated oral fluid exposure. Published data for CSFV oral tablet administration in commercial swine is limited; therefore the above parameters represent process boundaries extrapolated from live veterinary viral vaccine manufacturing and require challenge-trial confirmation.

Encapsulation of CSFV antigen powder into size 3 or size 4 hard hydroxypropyl methylcellulose capsules is carried out at 15 °C to 20 °C and not more than 30% relative humidity to prevent shell deformation and moisture uptake by the lyophilised antigen powder. If the powder is exposed to ambient humidity above 60% during staging, it must be pre-dried in a vacuum dryer at not more than 25 °C before encapsulation. The powder fill composition includes the lyophilised antigen stabilised with sucrose and gelatin, directly compressible mannitol, microcrystalline cellulose, and sodium starch glycolate as disintegrant; no magnesium stearate is used because the hydrophobic lubricant can delay wetting and the low-shear filling sequence does not require high lubrication. A low-speed tamping pin capsule filler is preferred over a dosator system; excessive tamping depth above 4 mm per stroke increases shear and heat generation in the powder bed. Gelatin capsules are avoided because residual moisture and potential aldehyde crosslinking can bind the viral envelope glycoproteins. The filled capsules are banded with a hypromellose banding solution, packaged in desiccant-stoppered HDPE bottles, and stored at 2 °C to 8 °C. Dissolution testing in 0.1 M hydrochloric acid is performed only to confirm capsule shell opening; potency is assessed by virus titration in cell culture because dissolution of the shell does not correlate with antigen integrity. The oral capsule presentation is not a registered commercial dosage form for CSFV in most jurisdictions, and formulation feasibility is limited by the acid lability of the live enveloped virus; therefore any capsule prototype must be challenged in target animals before making regulatory claims.

If Dry Premix Granulation Is Required, Thermal and Shear Exposure Must Be Decoupled from Antigen Activity

CSFV biological API intended for dry powder, granule, or feed premix presentation is not a conventional chemical premix and cannot survive standard feed pelleting at 70 °C to 85 °C unless the antigen is protected by encapsulation or the treated material is applied post-pelleting as a top-dress. The preferred industrial route is low-shear blending of lyophilised antigen powder with a non-hygroscopic carrier such as lactose monohydrate, calcium carbonate, or corn cob fraction. The carrier particle size is controlled by sieve analysis according to ISO 3310-1:2016; a carrier fraction between 150 µm and 710 µm reduces segregation while minimising dust generation. Blending is performed in a double-cone or ribbon blender at 4 rpm to 12 rpm for 5 min to 15 min; longer blending or higher speeds increase shear and electrostatic charge, which can cause active powder loss to the vessel wall. Blend uniformity is assessed by virus titration or antigen-capture ELISA at geometric sampling points, with acceptance criteria of relative standard deviation not more than 5% and no individual sample exceeding 10% of the target concentration. If a granulated intermediate is required, dry granulation by roller compaction at roll pressure not more than 20 kN and milling through a 1.0 mm screen preserves more antigen activity than wet granulation. Wet granulation with water and tray drying above 35 °C is contraindicated because the combination of moisture, heat, and shear reduces live virus titre rapidly. The terminal premix is administered as a top-dress on feed at ambient temperature; treated feed should be consumed within 4 h to 6 h to limit environmental inactivation. Amine-based additives and ammonia-releasing mineral premixes should be excluded because carbonyl-amine reactions can crosslink the viral envelope. Published data for CSFV oral premix administration in commercial swine is limited; the processing parameters above are based on general oral veterinary vaccine carrier practice and must be verified for the specific API lot and farm water quality.

Chlorine in drinking water is the single most immediate inactivation variable when CSFV antigen API is formulated as a concentrated oral solution or field-mixed drinking-water dose. Municipal and farm water supplies often carry residual free chlorine above 0.2 mg/L, which can disrupt the lipid envelope and eliminate live CSFV infectivity within minutes. Before reconstitution of the oral solution, the water matrix is treated with sodium thiosulfate at 50 mg/L to 100 mg/L or with skimmed milk powder at 2.5 g/L to neutralise chlorine and provide additional proteinaceous protection. The buffer capacity is adjusted to pH 6.8 to 7.4 using a phosphate or citrate buffer; pH below 6.0 and pH above 8.5 accelerate antigen degradation. The concentrated vaccine is added with gentle stirring in a polypropylene or stainless-steel tank; copper and galvanised piping are avoided because free copper ions destabilise the viral envelope. The finished oral solution is dosed through piglet drinking systems within 2 h to 4 h after mixing, because viability declines rapidly in aqueous environments. The terminal solution is not subjected to terminal sterilisation; therefore bioburden control is maintained by using filtered water and sanitary mixing vessels, and the bulk concentrate must meet a bioburden limit consistent with Ph. Eur. 5.1.4. A field-scale oral solution presentation for CSFV is not widely established as a commercial licensed product; published data for this specific configuration is limited, and regulatory acceptance would require challenge-trial demonstration in the intended pig population.