Isolation and molecular characterization of the first subgroup J avian leukosis virus from chicken in Pakistan.

Since subgroup J avian leukosis virus (ALV-J) was first isolated in the United Kingdom in 1988, it has seriously hindered the development of the poultry industry worldwide. Although cases of ALV-J infection have been reported as early as 2001 in Pakistan, there was no further research on the isolation and molecular characteristics of ALVs. In the present study, we first isolated two ALVs from suspicious clinical samples that were collected from a desi chicken farm in Pakistan. The results of multiplex PCR and indirect immunofluorescent antibody assays confirmed that the two isolates (PK19FA01 and PK19SA01) belonged to ALV-J. The complete genomes of the two isolates were amplified, sequenced, and systematically analyzed. We found that gp85 of PK19FA01 was more similar to that of the prototype strain HPRS103, whereas gp85 of PK19SA01 was more similar to that of American strains. The two isolates contained an intact E element of 147 residues and had a unique 135 bp deletion in the redundant transmembrane of the 3' untranslated region. The U3 region of the two isolates was highly homologous to that of American ALV-J strains. To our knowledge, this is the first report of the isolation, complete genome sequencing, and systematic molecular epidemiological investigation of ALV-J in Pakistan. Our findings could enrich epidemiological data and might contributed to more effective measures to prevent and control avian leukosis in Pakistan.

The first complete genome sequence and pathogenicity characterization of fowl adenovirus 11 from chickens with inclusion body hepatitis in Pakistan.

Inclusion body hepatitis (IBH), hydropericardium syndrome, and gizzard erosion associated with fowl adenovirus (FAdV) infections are reported globally and resulted in significant poultry industry economic losses. In 2018, severe IBH appeared in Pakistan in a 17-week-old layer flock. Subsequently, a FAdV-11 strain (designated as PKFAd18) was isolated from liver samples and identified based on phylogenetic analyses of the serotype-specific L1 region of the capsid hexon gene. There is no complete genome sequence of the Pakistani FAdV-11. This study successfully sequenced the complete genome of PKFAd18. The full genome of PKFAd18 contains 43 840 base pairs (bp) with a G + C content of 53.9 %, which is comparable to other FAdV serotypes. Similar to other FAdV-11 strains, PKFAd18 has only one fiber, while FAdV-1 and FAdV-4 have two fibers. Notably, PKFAd18 showed unique characteristics compared to other FAdV-11 strains. A natural large genomic deletion (1215 bp) appeared in tandem repeat region two, relative to the ON-NP2 strain. Phylogenetic analyses of the PKFAd18 penton gene showed higher homology with FAdV-9, highlighting potential natural recombination between FAdV-11 and FAdV-9. Moreover, the pathogenicity of PKFAd18 studied in specific-pathogen-free chickens showed that PKFAd18 is capable of inducing severe IBH and could be responsible for IBH in Pakistan. Thus, the first complete genome of FAdV-11 in Pakistan was sequenced in this study, which enriches the diversity of knowledge about FAdV-11 and is useful for developing diagnostics and vaccines for IBH induced by FAdV-11 in Pakistan.

Pathological effects of concurrent administration of aflatoxin B1 and fowl adenovirus-4 in broiler chicks.

The current study was designed to investigate pathological effects of fowl adenovirus in broilers exposed to aflatoxin B1. Fowl Adenovirus-4 (FAdV-4) infection is remerging in all types of poultry birds in Pakistan. Poultry feed contamination with mycotoxin (aflatoxin) is another important global issue. A total of 125-day old broiler birds were divided into six equal groups. Group A served as control. B and C groups were administered with aflatoxin B1 (AFB1) 100 and 200 µg/kg feed. Group D was infected with FAdV-4, while groups E and F administered with both AFB1 (100 & 200 µg/kg) along with FAdV-4. These birds were monitored for clinical signs and mortality. Feed intake, body weight (BW), relative organ weights and gross & histopathological lesions were recorded. The highest mortality was observed in group F (FAdV-4 + AFB1 200 µg/kg feed) and the lowest mortality was observed in group B (AFB1 100 µg/kg feed). Body weights of all the groups were significantly (p < 0.05) lower as compared with control group. Relative weight of liver and kidneys in groups E and F were significantly higher as compared with control. Grossly, liver was swollen, anemic with round margins in groups D, E and F. Kidneys were also swollen with whitish areas indicating dead tissue. Microscopically intranuclear inclusion bodies were observed in group D-F. The hepatic parenchyma was also indicating necrotic changes along with vacuolar degeneration. In renal parenchyma, acute tubular necrosis was observed in groups C, E and F. It was concluded that AFB1 intoxication lead to dose dependent changes in liver and kidneys. Severity of the changes was increased in interactive groups of AFB1 with FAdV-4. Therefore, feed should be regularly monitored for AFB1 levels and day old chicks for vertically transmitted FAdV-4 to prevent losses.