Effect of strain-specific maternally-derived antibodies on influenza A virus infection dynamics in nursery pigs.

Fabian Orlando Chamba Pardo,Marie Rene Culhane,Andres Perez,Spencer Wayne,Matthew Allerson,Montserrat Torremorell,Stephen Mark Tompkins

doi:10.1371/journal.pone.0210700

Fabian Orlando Chamba Pardo, Marie Rene Culhane + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0210700

Copy DOI

Journal: PloS one	Publication Date: Jan 14, 2019
Citations: 21	License type: CC BY 4.0

Affiliation: University of Minnesota, Pipestone (United States)

Abstract

Reducing the number of influenza A virus (IAV) infected pigs at weaning is critical to minimize IAV spread to other farms. Sow vaccination is a common measure to reduce influenza levels at weaning. However, the impact of maternally-derived antibodies on IAV infection dynamics in growing pigs is poorly understood. We evaluated the effect of maternally-derived antibodies at weaning on IAV prevalence at weaning, time of influenza infection, number of weeks that pigs tested IAV positive, and estimated quantity of IAV in nursery pigs. We evaluated 301 pigs within 10 cohorts for their influenza serological (seroprevalence estimated by hemagglutination inhibition (HI) test) and virological (prevalence) status. Nasal swabs were collected weekly and pigs were bled 3 times throughout the nursery period. There was significant variability in influenza seroprevalence, HI titers and influenza prevalence after weaning. Increase in influenza seroprevalence at weaning was associated with low influenza prevalence at weaning and delayed time to IAV infection throughout the nursery. Piglets with IAV HI titers of 40 or higher at weaning were also less likely to test IAV positive at weaning, took longer to become infected, tested IAV RT-PCR positive for fewer weeks, and had higher IAV RT-PCR cycle threshold values compared to piglets with HI titers less than 40. Our findings suggest that sow vaccination or infection status that results in high levels of IAV strain-specific maternally-derived antibodies may help to reduce IAV circulation in both suckling and nursery pigs.

Highlights

Influenza A virus (IAV) is a primary cause of acute respiratory disease in pigs and it is part of the porcine respiratory disease complex (PRDC), which includes other pathogens such as porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus 2 (PCV2), and Mycoplasma hyopneumoniae [1]
H1N1, H1N2 and H3N2 are the most common subtypes found in pigs and the introduction of gene segments from other species into a pool of endemic viruses has resulted in a complex landscape of influenza A virus (IAV) in pigs
Our results indicated that the hemagglutination inhibition (HI) antibodies at weaning affected IAV infection dynamics in the nursery

Summary

Introduction

Influenza A virus (IAV) is a primary cause of acute respiratory disease in pigs and it is part of the porcine respiratory disease complex (PRDC), which includes other pathogens such as porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus 2 (PCV2), and Mycoplasma hyopneumoniae [1]. Currently there are 16 genetically and antigenically distinct H1 clades (alpha, beta, gamma, gamma 2, delta 1a, delta 1b, delta 2 and pandemic 2009) [15, 17, 27] or H3 clusters (IV A-F, human-like 2011 and human-like 2016) [9, 14, 28, 29] of IAV co-circulating in US pigs This broad genetic diversity and the common co-circulation of several clades within a farm or production system represents a critical hurdle for vaccines to induce cross-protective immunity effective against genetically diverse strains [30, 31]

Methods

Results

Discussion

Conclusion