Enteric Virus Diversity Examined by Molecular Methods in Brazilian Poultry Flocks

Abstract

Enteric viruses play an important role in the Brazilian poultry industry due to the economic impact of resulting low yields of broilers, layers, and breeders. The most common enteric viruses affecting commercial flocks in Brazil include Fowl Adenovirus of group I (FAdV-I), Chicken Parvovirus (ChPV), Chicken Astrovirus (CAstV), Avian Nephritis Virus (ANV), Infectious Bronchitis Virus (IBV), Avian Reovirus (AReo), and Avian Rotavirus (ARtV). The aim of this study was to identify single and multiple infections using data obtained from 270 samples from eleven Brazilian states, corresponding to the period between 2010 and 2017. This was accompanied by an analysis of the relationship between the age of birds, clinical signs, and geographical distribution, using Polymerase Chain Reaction (PCR) and Reverse Transcription-PCR (RT-PCR) techniques. Twenty-five profiles of virus combinations were detected. Single infections were encountered in 86.3% of samples, and multiple infections were present in the remaining 13.7%. Both single and multiple infections affected all kinds of commercial chickens with digestive problems, stunting syndrome, decreases in egg and meat production, increased mortality, and respiratory signs. FAdV-I, ChPV, CAstV, ANV, and ARtV were mostly detected in young broilers, in contrast with IBV, which was detected in hens from one to greater than 51 weeks of age. These results exhibit the complexity of enteric diseases and the still poorly understood role of each pathogen as a unique etiological agent.

Development of a Sensitive Real-Time Fast-qPCR Based on SYBR® Green for Detection and Quantification of Chicken Parvovirus (ChPV)

“…Similar results were found in the present study in which apparently healthy chickens also showed high viral concentrations [ 22 ]. ChPV has been detected in chickens independently of zootechnical interest and in many regions around the world with high chicken production, such as Europe [ 10 , 17 , 18 ], China [ 35 ], South Korea [ 36 ], North America [ 8 , 37 , 38 ], Brazil [ 9 , 16 , 24 , 25 ], and Ecuador [ 26 , 38 ]; however, its presence remains unknown in the rest of South America. The present study also showed that the virus was detected at earlier and later ages in chickens, demonstrating that virus dissemination can occur at any time [ 21 ].…”

Isolation of avian nephritis virus from chickens showing enteric disorders

“…Actually, ANV has been reported around the world and has been detected in many countries and on all continents. In recent years, ANV was detected in Brazil in chickens and turkeys showing signs of enteric diseases, principally signs of RSS (Hewson et al, 2010 ; Mettifogo et al, 2014 ; Moura-Alvarez et al, 2014 ; Luna et al, 2016 ; De la Torre et al, 2018 ). The implication or relation of this virus in RSS pathogeneses is not well clear.…”

“…From day 3 to 21, the virus was also detected in the bursa, jejunum, and spleen, but no alterations were found (Imada et al, 1979 , 1981 ; Shirai et al, 1991 ), showing that the target organ of this virus is kidneys, but it could be present in other organs, such as gut. Actually, ANV is related to one of the principal causative agents of enteric problems, more specifically those related with RSS (Kang et al, 2012 ; Day and Zsak, 2013 ; Mettifogo et al, 2014 ; Day et al, 2015 ; Smyth, 2017 ; De la Torre et al, 2018 ). The samples used here were from chickens showing signs of enteric diseases that were positive only for ANV after molecular screening, suggesting that the principal agent is involved in the genesis of some enteric problems may be ANV.…”

“…The sequencing of ORF 1b gene is not used for astrovirus genotyping where the capsid gene (ORF2) is used (Todd et al, 2011 ; Smyth et al, 2017 ; Luna et al, 2016 ), but could show similarities or differences between sequences from different serotypes of ANV. Recently, the presence of ANV in chickens, layer hens, and breeders showing signs of enteric diseases was reported in Brazil (Nuñez and Ferreira, 2013 ; Mettifogo et al, 2014 ; Luna et al, 2016 ; De la Torre et al, 2018 ), and many outbreaks of enteric diseases have also been observed (unpublished data). The role of ANV in enteric disease in Brazilian chicken flocks is not well understood, and because there is a lack of viral isolates, it is difficult to study this virus.…”

“…Enteric diseases are a big problem for animal health as well as in the poultry industry. Infected birds are affected from the first day of birth showing early clinical signs of enteric diseases, principally diarrhea; however, chickens of different ages are also affected, whether or not they are showing clinical signs (Pantin-Jackwood et al, 2007 ; Smyth et al, 2009 ; Todd et al, 2010 ; Mettifogo et al, 2014 ; Veen et al, 2017 ; Xue et al, 2017 ; De la Torre et al, 2018 ; Kang et al, 2018 ). In poultry, runting-stunting syndrome ( RSS ) is of great relevance to avian intestinal health, and many viruses are involved (Pantin-Jackwood et al, 2008 ; Day et al, 2015 ; Smyth, 2017 ).…”