Inactivated infectious bronchitis virus vaccine encapsulated in chitosan nanoparticles induces mucosal immune responses and effective protection against challenge

Abstract

Avian infectious bronchitis virus (IBV) is one of the most important viral diseases of poultry. The mucosa of upper respiratory tract, specially the trachea, is the primary replication site for this virus. However, conventional inactivate IBV vaccines usually elicit reduced mucosal immune responses and local protection. Thus, an inactivated IBV vaccine containing BR-I genotype strain encapsulated in chitosan nanoparticles (IBV-CS) was produced by ionic gelation method to be administered by oculo-nasal route to chickens. IBV-CS vaccine administered alone resulted in markedly mucosal immune responses, characterized by high levels of anti-IBV IgA isotype antibodies and IFNγ gene expression at 1dpi. The association of live attenuated Massachusetts IBV and IBV-CS vaccine also induced strong mucosal immune responses, though a switch from IgA isotype to IgG was observed, and IFNγ gene expression peak was late (at 5 dpi). Efficacy of IBV-CS was evaluated by tracheal ciliostasis analysis, histopathology examination, and viral load determination in the trachea and kidney. The results indicated that IBV-CS vaccine administered alone or associated with a live attenuated heterologous vaccine induced both humoral and cell-mediated immune responses at the primary site of viral replication, and provided an effective protection against IBV infection at local (trachea) and systemic (kidney) sites.

A Recombinant La Sota Vaccine Strain Expressing Multiple Epitopes of Infectious Bronchitis Virus (IBV) Protects Specific Pathogen-Free (SPF) Chickens against IBV and NDV Challenges

“…The ciliostasis activity of the tracheal explants was examined on 10 tracheal ring explants per chicken (5 chickens of each group) 5 dpc. The tracheas were carefully removed and examined for ciliary activity within 2 h after collection as described in the referenced papers [43,44]. Briefly, 1 to 2 mm sections from the middle of each trachea were prepared and examined under a low-power microscope, and ciliary activity was scored as follows: 0, denotes all beating cilia; 1, 75% beating; 2, 50% beating; 3, 25% beating; and 4, absence of beating (100% ciliostasis).…”

Infectious Bronchitis Coronavirus Infection in Chickens: Multiple System Disease with Immune Suppression

“…Given the available scientific evidence against IB vaccination at the hatchery [ 106 , 110 ], it may also be appropriate to postpone the first IB vaccination to a barn vaccination done at seven days of age relying on maternal antibody response to protect the chickens during the first week of life [ 110 ]. There are numerous issues surrounding the use of live attenuated IB vaccines [ 11 , 99 , 119 , 120 , 121 , 122 , 123 , 124 , 125 , 126 ], and relying on inactivated vaccines can be an option, but they inherently lack the ability to induce mucosal immune response, which is critical for the control of IB [ 131 , 132 , 133 ]. It is possible that inactivated vaccines can be used for the induction of mucosal immune response when combined with various nanoparticles [ 132 ].…”

Avian Infectious Bronchitis Virus: Immunogenicity Profiles and New Pathotypes in Brazil - Literature Review

“…Além disso, vacinas vivas atenuadas são importantes na imunoprofilaxia da infecção pelo VBI para aves dos diferentes tipos de criação, e as vacinas inativadas em emulsão oleosa antecedidas da imunização com vacina viva atenuada, são especialmente recomendadas para conferir uma maior imunoproteção a aves poedeiras e reprodutoras (BANDE et al, 2015). As vacinas vivas atenuadas conferem imunidade local mais efetivas no trato respiratório, entretanto, há o risco de patogenicidade residual, reversão de virulência e persistência nas aves de uma granja vacinada, enquanto que as vacinas inativadas são menos efetivas em induzir proteção no compartimento das mucosas e, principalmente os mecanismos mediados por células Tc (CHHABRA et al, 2015;LOPES et al, 2018;MCKINLEY et al, 2008). Dentre as vacinas atenuadas, estão disponíveis no Brasil, aquelas que são formuladas com as estirpes atenuadas do genótipo / sorotipo Massachusetts, como a H52 e a H120, derivadas da amostra Holland (H) e ainda a estirpe atenuada Ma5.…”

“…Um ponto interessante a considerar na imunoprofilaxia da BIG é que para se obter uma eficiente proteção contra a infecção pelo VBI, é necessário identificar os genótipos / sorotipos desse vírus predominantes para cada região / pais e também determinar o potencial de proteção cruzada, isto é, o protectotipo das estirpes vacinais existentes em relação às novas estirpes do VBI isoladas de campo, procurando, dessa forma, otimizar os programas estratégicos de vacinação contra a BIG (CHHABRA et al, 2015;COOK et al, 2012;JORDAN, 2017 (LOPES et al, 2018).…”

“…Estas estirpes muitas vezes se manifestam de maneira diferente das comumente associadas com a BIG em nosso país. Portanto, o principal desafio para a comunidade científica e para o setor técnico da avicultura do Brasil é saber o estado de proteção imune efetivamente desencadeado pela vacinação com as estirpes preconizadas e/ou oficialmente autorizadas em nosso país, frente a estas novas variantes do genótipo BR do VBI e de forma a ter mais subsídios para procurar desenvolver vacinas mais eficazes contra essas estirpes do VBI, bem como programas imunoprofiláticos mais efetivos contra esse agente infeccioso (FERNANDO et al, 2013;LOPES et al, 2018;OKINO et al, 2013).…”