A retrospective PCR investigation of avian Orthoreovirus, chicken infectious anemia and fowl Aviadenovirus genomes contamination in commercial poultry vaccines in Brazil

Chicken anemia virus and avian gyrovirus 2 as contaminants in poultry vaccines

This study focuses on the detection of chicken anemia virus (CAV) and avian gyrovirus 2 (AGV2) genomes in commercially available poultry vaccines. A duplex quantitative real-time PCR (dqPCR), capable of identifying genomes of both viruses in a single assay, was employed to determine the viral loads of these agents in commercially available vaccines. Thirty five vaccines from eight manufacturers (32 prepared with live and 3 with inactivated microorganisms) were examined. Genomes of CAV were detected as contaminants in 6/32 live vaccines and in 1/3 inactivated vaccines. The CAV genome loads ranged from 6.4 to 173.4 per 50 ng of vaccine DNA (equivalent to 0.07 to 0.69 genome copies per dose of vaccine). Likewise, AGV2 genomes were detected in 9/32 live vaccines, with viral loads ranging from 93 to 156,187 per 50 ng of vaccine DNA (equivalent to 0.28-9176 genome copies per dose of vaccine). These findings provide evidence for the possibility of contamination of poultry vaccines with CAV and AGV2 and they also emphasize the need of searching for these agents in vaccines in order to ensure the absence of such potential contaminants.

Occurrence of Aviadenovirus in chickens from the poultry industry of Minas Gerais

The occurrence of Aviadenovirus (FAdV) was investigated in chickens from the poultry industry of Minas Gerais state, Brazil. The investigation was conducted due to the scarcity of recent data in the country and its description in neighboring countries. For this purpose, livers were collected from layer chicks (n=25), older layers (n=25), broilers (n=300), and livers (n=25) and stool (n=25) samples from broiler breeders, representing the major poultry regions of the state. FAdV DNA was demonstrated using a previously described PCR protocol for amplifying part of the hexon gene encoding sequence. FAdV was found in layer chicks (36%), widespread (100%) in older layers, and with regional differences in broilers (24-86%). Although all broiler breeder stools were negative, FAdV DNA was detected in livers (16%, 4/25) of stool-negative birds. In order to obtain additional information on the circulation of the infection, livers of subsistence chickens collected from one poultry intensive region, were evaluated (n = 12), with FAdV being detected in all samples. FAdV was found in young and old layers, broilers, broiler breeders and free-range chickens, and results suggest the circulation of FAdV among different types of chickens. The detection in older layer chickens may indicate an extended risk of horizontal transmission in regions of Minas Gerais with mixed activity of egg and meat type chickens and poor biosecurity strategies. The infection in breeders may indicate vertical transmission and the continuous production of infected progenies. The hexon-gene-targeted PCR amplicon sequences aligned with FAdV of species D of Aviadenovirus. Results indicate the necessity for biosecurity, especially for breeders, separating flocks according to origin, age and health status, which will be an advantage regarding any pathogen.