• Vaccine Ontology ID: VO_0004104
• Type: Monoclonal antibody
• Antigen: No VEE virus antigens were used for this vaccination approach. The monoclonal antibodies are specifically designed against VEEV surface glycoproteins E1 and E2.
• Preparation: The monoclonal antibodies (MAB) are: (1). the VEEV surface glycoprotein E2-specific monoclonal antibodies 1A4A-1; (2). the VEEV surface glycoprotein E2-specific monoclonal antibodies 1A3B-7; (3) the glycoprotein E1-specific MAB 3B2A-9; (4) 4. the E1-specific MAB MH2. All MAB were produced and purified by protein G affinity chromatography as previously described (Phillpotts et al., 2002).
  
  Strains of VEEV from serogroups IA/B (Trinidad donkey; TrD), IC (P676), ID (3880), IE (Menall), IF (78v-3531), II (Fe37c), IIIA (Mucambo BeAn8), IV (Pixuna BeAn356445), V (Cabassou CaAr508) and IV (AG80-663) are used.
  For the preparation of virus stocks, suckling mice were infected intracerebrally with a 1/1000 dilution of each virus. Infected brains were harvested at 24 h, prepared as 10% tissue suspensions in L15MM and clarified by centrifugation at 10,000 × g for 15 min. Alternatively viruses were propagated in Vero cell monolayers inoculated with an m.o.i. of 0.01 and harvested when 50–75% of the cell sheet showed evidence of virus cytopathic effect (CPE). The titre of each VEEV strain was determined by plaque formation under a carboxymethyl cellulose overlay in BHK21 cells.
• Virulence: Not virulent
• Description: Using a murine model to study monoclonal antibody (MAB) a VEEV complex-specific, glycoprotein E2-binding MAB was identified, able to protect against disease induced by exposure to aerosolised VEEV from serogroups I, II and IIIA (mouse-virulent strains). There was no synergy in protection between anti-E1 and anti-E2 MAB. Assays of MAB virus neutralising activity in a homologous (mouse fibroblast) cell line suggested that neutralisation played a significant role in protection in addition to the previously reported mechanism of Fc receptor-binding [Mathews et al., 1985. J. Virol. 55, 594–600]. Development of an analogous human MAB with identical VEEV epitope specificity may be informed and monitored by reference to these properties (Phillpotts, 2006).

Mouse Response

• Host Strain: Balb/c mice
• Vaccination Protocol: Balb/c mice, 3–4 (s.c. challenge) or 6–8 (airborne challenge) weeks old (Charles River Laboratories, UK) were passively immunized intraperitoneally (i.p.) 24 h before exposure to virulent virus with MAB diluted in PBS.
• Side Effects: No side effect
• Challenge Protocol: The challenge route was either s.c. (100 μl virus-containing suspension in PBS) or via the airborne route, by exposure for 20 min to a poly disperse aerosol generated by a Collison nebuliser (Phillpotts et al., 1997). Mice were contained loose within a closed box during airborne challenge. The virus dose was calculated by sampling the air in the box and assuming a respiratory minute volume for mice of 1.25 ml/g (Guyton, A.C., 1947). After challenge, mice were observed twice daily for clinical signs of infection (piloerection, hunching, inactivity, excitability and paralysis) by an observer who quantified these and was unaware of the treatment allocations. These clinical signs are typical of VEEV infection and occurred in all mice challenged with VEEV.
  In previous studies (Phillpotts et al., 2002) their association with VEEV infection as the cause of death has been confirmed by the isolation of virus from brain and other internal organs. In accordance with UK Home Office requirements and as previously described, humane endpoints were used (Wright et al., 1998). These experiments therefore record the occurrence of severe disease rather than mortality. Even though it is rare for animals infected with virulent VEEV and showing signs of severe illness to survive, our use of humane endpoints should be considered when interpreting any virus dose expressed here as 50% lethal doses (LD50).
• Efficacy: MAB MH2, 3B2A-9 and 1A3B-7 may be broadly reactive and potentially able to protect against a range of VEEV strains. There was also the possibility that the combination of E1- and E2-specific MAB could lead to synergy in protection. MAB 1A4A-1 while not broadly reactive, was able to bind strongly to, neutralise and protect against challenge with some VEEV strains. It was therefore included in these experiments as a positive control.
• Description: The challenge route was either s.c. (100 μl virus-containing suspension in PBS) or via the airborne route, by exposure for 2