Evaluation of protection in the face of maternal antibodies (mAb)1
A vaccination challenge study was performed to demonstrate that live attenuated influenza virus (LAIV) reduced infection from heterologous H1N2 and H3N2 challenges in piglets farrowed from IAV antibody–positive sows.†
This study demonstrated that a 1-mL intranasal LAIV vaccination of neonatal pigs ≥ 3 days of age in the face of maternal antibodies reduced both the number and duration of animals shedding when challenged by a heterologous H3N2 or H1N2, as measured by clinical signs and nasal virus isolation.
† Determined by positive results from ELISA (IDEXX AI MultiS‑Screen Ab Test, IDEXX; Westbrook, ME USA) and HI (> 1:10; H1N1 [99] HI and H3N2 C1/3 HI, Iowa State University‑Veterinary Diagnostic Laboratory).
Ingelvac Provenza™ spread and shedding
A study was performed to determine the spread (throughout airway mucosa) and shed (to sentinel pigs) of Ingelvac Provenza™ when administered intranasally to newborn pigs.
Briefly, 8 litters of 6 piglets were born to IAV-seronegative sows. Half of each litter was randomly assigned to vaccinated or sentinel groups. Pigs in the vaccinated group were administered 1 mL of Ingelvac Provenza™ intranasally, whereas the other half of each litter remained untreated as a contact sentinel group.
The attenuation of the vaccine viruses when administered intranasally to newborn pigs was demonstrated by very minor lesions observed at the D14 necropsy, and no pigs shedding virus in nasal secretions past D7. By D14 necropsy, the highest lung lesion in a vaccinated pig was 0.8%, which further illustrates the attenuation of the vaccine viruses. The vaccine demonstrated dissemination to lung and tonsillar tissues as evidenced by detection of the virus in those tissues and bronchoalveolar lavage fluid (BALF) and upper respiratory lavage fluid (URLF) in 7 and 8 pigs at 3 days post vaccination.
* All samples were evaluated using virus isolation and then confirmed as IAV by PCR.
† One sample was insufficient for testing.
Twenty of 24 pigs had at least 1 positive nasal swab sample. Within 3 days post vaccination, 17/24 vaccinated pigs had shed the virus in nasal swabs at least once. The longest duration of shedding was 7 days, noted in a single pig, and 5 of 16 pigs shed the virus for 6 days.
No sentinel pigs exhibited nasal/ocular discharge, nor sneezing, depression, lethargy, or recumbency, and all maintained rectal temperatures between 38.4˚C and 40.5˚C.
Exposure to the virus via shedding from vaccinated pigs did not result in positive nasal swabs in sentinel pigs or dams at any time (day 0 to day 14) during the study. In addition, no sentinel pigs had lung lesions, and no sentinel pigs at 14 days post challenge had any positive samples at necropsy. For the dams necropsied on day 14, all nasal swabs and tissues tested were negative with the exception of the BALF and URLF of 1 dam.
NS = nasal swab.
* All samples were evaluated using virus isolation and then confirmed as IAV by PCR.
