Local and systemic isotype-specific antibody responses to equine influenza virus infection versus conventional vaccination

• Published in: Vaccine Vol. 16; no. 13; pp. 1306 - 1313
• Main Authors: Nelson, K.M., Schram, B.R., McGregor, M.W., Sheoran, A.S., Olsen, C.W., Lunn, D.P.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-08-1998; Elsevier
• Subjects: Animals; Antibodies, Viral - biosynthesis; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Horse Diseases - immunology; Horse Diseases - prevention & control; Horses; Immunity, Mucosal; Immunoglobulin A - biosynthesis; Immunoglobulin A, Secretory - biosynthesis; Immunoglobulin G - biosynthesis; Influenza A virus - immunology; Influenza Vaccines - immunology; influenza virus; Microbiology; mucosal immunity; Nasal Mucosa - immunology; Orthomyxoviridae Infections - immunology; Orthomyxoviridae Infections - prevention & control; Orthomyxoviridae Infections - veterinary; Recurrence; Replicative cycle, interference, host-virus relations, pathogenicity, miscellaneous strains; Vaccination - veterinary; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies; Virology; Virus Shedding - immunology; influenza virus; horses; mucosal immunity; Immune response; Antibody; Mucosa; Orthomyxoviridae; Vaccine; Infection; Virus; Equine influenzavirus; Vertebrata; Local immunity; Experimental disease; Influenzavirus A; Mammalia; Animal; Viral disease; Horse; Perissodactyla; Veterinary; Ungulata; Comparative study; Humoral immunity
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/S0264-410X(98)00009-7

Inactivated alum-adjuvanted conventional equine influenza virus vaccines are of poor efficacy and offer limited short-term protection against infection. In sharp contrast, natural infection with equine influenza virus confers long-term protective immunity. In order to identify the protective immune responses to equine influenza virus, the influenza virus-specific IgA, IgGa, IgGb, IgGc and IgG(T) antibody responses in nasal secretions and serum induced by natural infection and a commercial vaccine were studied by ELISA. Two groups of four influenza-naive ponies were established. In the natural infection group, ponies received 10
8.5 EID
50 of A/equine/Ky/1/81 by intranasal instillation, were allowed to recover, and then were rechallenged 100 days later. All four ponies exhibited clinical signs of influenza virus infection and viral shedding following primary infection, but were completely protected from challenge infection. Antibody responses to primary infection were characterized by nasal IgA and serum IgGa and IgGb responses. Ponies in the conventional vaccine group received a commercially available vaccine by intramuscular injection followed by a booster injection 3 weeks later. Challenge infection 100 days after vaccination resulted in clinical signs of infection and viral shedding. Antibody responses to vaccination were restricted to serum IgG(T) responses only. These results demonstrate that the protective immunity generated by natural equine influenza virus infection is associated with a mucosal IgA immune response and humoral IgGa and IgGb sub-isotype responses, and that this pattern of response is not generated by conventional vaccines.