No abstract

Abstract

Antigenic drift of avian influenza viruses (AIVs) has been observed in chickens after extended vaccination program, similar to those observed with human influenza viruses. To evaluate the evolutionary properties of endemic AIV under high vaccination pressure (around 2 billion doses used in the last 12 years), we performed a pilot phylogenic analysis of the hemagglutinin (HA) gene of AIVs isolated from 1994 to 2006. This study demonstrates that Mexican low pathogenicity (LP) H5N2-AIVs are constantly undergoing genetic drifts. Recent AIV isolates (2002–2006) show significant molecular drifts when compared with the H5N2 vaccine-strain or other field isolates (1994–2000). This study also demonstrates that molecular drifts in the HA gene lineages follow a yearly trend, suggesting gradually cumulative sequence mutations. These findings might explain the increasing incidence of LP H5N2 AIV isolated from commercial avian farms. These findings support recent concerns about the challenge of AIV antigenic drift and influenza epidemics.

Highly virulent fowl aviadenoviruses (genus: Aviadenovirus) represent a significant risk in poultry farming that may contribute to increased mortality rates and may adversely affect the growth performance of poultry flocks. In this study, we performed the clinicopathological characterization of a FAdV strain SHP95 isolated from a commercial farm and its whole genome sequencing. The study revealed that the isolated strain is a highly virulent serotype 4 FAdV that can cause 100% mortality in day-old specific pathogen free (SPF) chickens with a dose of 2.5 × 10(5) TCID50. At a lower viral dose (1.5 × 10(4) TCID50), the infection in day-old SPF chickens caused 40% mortality and lesions characteristic for Hepatitis-hydropericardium syndrome (HHS). The viral strain was detectable by real time PCR in chicken organs, including the lymphoid organs until day 28 after infection. The whole genome assembly of strain SHP95 revealed a size of 45,641 bp, which encodes for 42 viral open reading frame (ORF). The comparative analysis in the genome shows 98.1% similarity between strain SHP95 and other FAdV-4 genomes reported. The major differences in the genome sequence between pathogenic and non-pathogenic fowl Adenovirus were identified in the right arm of the genome.

No abstract

The protective effect of hyperimmune IgY fraction of egg yolk prepared from hens hyperimmunized with multiple species of Eimeria oocysts on experimental coccidiosis was evaluated in young broilers. Chickens were continuously fed from hatch with a standard diet containing hyperimmune IgY egg yolk powder or a nonsupplemented control diet and orally challenged at d 7 posthatch with 5.0 x 10(3) sporulated Eimeria acervulina oocysts. Body weight gain between d 0 and 10 and fecal oocyst shedding between d 5 and 10 postinfection were determined as parameters of protective immunity. Chickens given 10 or 20% hyperimmune IgY egg yolk powder showed significantly increased BW gain and reduced fecal oocyst shedding compared with control birds fed the nonsupplemented diet. In another trial, lower IgY concentrations (0.01, 0.02, and 0.05%) were used to treat birds with 1.0 x 10(4) oocysts of E. acervulina. Total oocyst shedding was significantly (P< 0.05) reduced in chickens fed the 0.02 and 0.05% hyperimmune IgY supplemented-diets compared with animals fed the nonsupplemented diet. Similarly, chickens fed 0.5% of hyperimmune IgY egg yolk powder diet and challenged with 1.0 x 10(4) oocysts exhibited reduced oocyst shedding compared with the control birds given 0.5% of IgY from nonimmunized hen eggs, although BW gain was not affected. We conclude that passive immunization of chickens with anti-coccidia IgY antibodies provide protective immunity against coccidiosis challenge infection.