Infection route is key to testing the effectiveness of swine flu vaccines

• Autores: J.D. Hemmink, S.B. Morgan, Mario Aramouni, H. Everett, F. J. Salguero, L. Canin
• Localización: Veterinary Record, ISSN-e 2042-7670, Vol. 179, Nº. 25, 2016
• Idioma: inglés
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• Resumen

  • Influenza A virus (IAV) is an important zoonotic pathogen that can cause substantial mortality and be rapidly disseminated through avian (ducks and chickens) and mammalian (human and pig) populations. Experimentally, influenza virus is delivered to pigs intranasally, by intratracheal instillation or by aerosol, but there is little data comparing the outcome of different methods.

    In order to determine the most relevant model for assessment of IAV pathogenesis, transmission, vaccine efficacy or therapeutic intervention, this study evaluated which method of experimental delivery of swine IAV to the upper or lower respiratory tract, by intranasal or aerosol method, best represented natural infection.

    Viral shedding pattern, cytokine responses in nasal swabs and immune responses following delivery of low or high dose swine influenza H1N1 virus to the respiratory tract of pigs intranasally or by aerosol were evaluated and compared to those induced in naturally infected contact pigs.

    Results indicated that viral multiplication and the immune response in naturally infected animals differs from those of animals experimentally infected by different doses and methods.

    Virus administered by aerosol was more effective than the intranasal method in reaching the lower respiratory tract. Although animals infected intranasally required a higher dose to establish an infection, the animals produced more virus and were better able to transmit it once infected. In contrast, those infected with a high dose of virus by aerosol did not transmit it efficiently.

    Natural infection by contact was found to be the most efficient route – inducing a strong immune response (innate and adaptive), even when the animals were exposed to a very low virus dose.

    The strong response more closely resembled the immune response generated by directly inoculating animals using a high dose of virus.

    The authors conclude that consideration of these differences is important for studies of disease pathogenesis and assessment of vaccine protective efficacy