Immunization and Host Responses to MB-1, a Live Hatchery Vaccine against Infectious Bursal Disease

Yossi Wein*, Virginie Loeb, Aderajew Asmare, Saar Tal, Avner Finger, Aharon Friedman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


MB-1 is an attenuated infectious bursal disease virus vaccine. Previously, we observed a temporal delay of vaccine virus replication in the bursae of chicks due to maternally derived antibodies (MDAs). The mechanism that allowed its survival despite MDA neutralization remained unclear. We hypothesized that after vaccination at 1 day of age (DOA), the MB-1 virus penetrates and resides in local macrophages that are then distributed to lymphoid organs. Furthermore, MB-1’s ability to survive within macrophages ensures its survival during effective MDA protection. PCR analysis of lymphoid organs from chicks with MDA, vaccinated on 1 DOA, demonstrated that the MB-1 virus was identified at low levels solely in the spleen pre-14 days of age. Fourteen days after vaccination, the virus was identified using PCR in the bursa, with viral levels increasing with time. The possible delay in viral colonization of the bursa was attributed to the presence of anti-IBDV capsid VP2 maternal IgA and IgY in the bursa interstitium. These indicate that during the period of high MDA levels, a small but viable MB-1 viral reservoir was maintained in the spleen, which might have served to colonize the bursa after MDA levels declined. Thereafter, individual immunization of chicks against Gumboro disease was achieved.

Original languageAmerican English
Article number1316
Issue number8
StatePublished - Aug 2023

Bibliographical note

Publisher Copyright:
© 2023 by the authors.


  • MB1-vaccine
  • gumboro
  • infectious bursal disease (virus)
  • maternal antibodies


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