Evaluation of the Viral Interference between Lentogenic Newcastle Disease Virus (Lasota) and Avian Influenza Virus (H9N2) using Real-Time Reverse Transcription Polymerase Chain Reaction in SPF Chicken

Abstract

Lentogenic Newcastle disease virus (lNDV) such as Lasota strain and low pathogenicity avian influenza such as H9N2 virus are two of the most economically important viruses affecting poultry worldwide, and little attention in recent years has been paid to simultaneous infections in chickens with these two viruses for the reason that co-infection do occur but are not easily detected. In the present study, chickens were inoculated with lNDV (Lasota) and LPAIV (A/chicken/Tehran/ZMT-173/99(H9N2)) simultaneously or sequentially three days apart. Oropharyngeal and cloacal swabs were collected from chickens from 1 to 14 days after inoculation. RRT-PCR for AIV and NDV detection was performed. The rate of viral shedding was measured within 14 days. No clinical symptoms were observed during the experiment however the pattern of virus shed was different with co-infection, thus comparing the results obtained from viral shedding showed that AIV is a much stronger agent than NDV in the occurrence of viral interference. This is due to the fact that in simultaneous inoculation, AIV replication delayed and reduced NDV replication, while replication of Lasota in simultaneous or pre-inoculated inoculation could not significantly disrupt H9N2 virus replication. These findings indicate that the infection with one virus can interfere with the replication of another, modifying the pathogenesis of the viruses. So, infection of the host with both viral agents simultaneously causes higher shedding of LPAIV than lNDV in OP and CL areas. In conclusion, coinfection with LPAVI in chickens did not impact clinical signs but affected the replication dynamics of these viruses.

Development of a coagglutination kit as a rapid test for diagnosing Newcastle disease in poultry

“…ND commonly causes several clinical signs, including respiratory symptoms and neurologic and digestive problems. Moreover, ND can manifest clinical signs similar to those of avian influenza (AI) [ 4 ]. As a result, the Office International des Epizooties (OIE) has recommended several standard diagnostic methods for the detection of ND, including virus isolation and molecular tests [ 5 ].…”

Study of the underlying mechanisms and consequences of pathogenicity differences between two in vitro selected G1-H9N2 clones originating from a single isolate

“…Ellakany et al observed that H9N2 infection reduced ND vaccine efficacy [23]. The presence of H9N2 in the host can induce a negative impact on the production of anti-Newcastle disease antibodies (i) either by the viral interference in which the growth of lentogenic Lasota strain—a commonly used as live vaccines against virulent form of NDV—could be suppressed or delayed [24] (ii) or by the immunosuppressive effect in which the immune organs could be damaged or destroyed following H9N2 infection [25, 26]. Furthermore, even in the presence of good herd immunity against NDV, H9N2 is also able to cause a vaccinal break as the simultaneous infection of H9N2 made birds more susceptible to velogenic NDV by lowering the minimum dose required to establish an infection and exacerbating clinical signs [27].…”

Quantitative evaluation of viral interference among Egyptian isolates of highly pathogenic avian influenza viruses (H5N1 and H5N8) with the lentogenic and velogenic Newcastle disease virus genotype VII in specific pathogen-free embryonated chicken eggs model

“…The prior growth of NDV may inhibit AIV growth resulting in false-negative AIV tests [11]. In a coinfection study, LPAIV had a negative impact on NDV growth when they were inoculated simultaneously or sequentially [12]. The previous infection of specific pathogen-free (SPF) chickens with virulent NDV strains can suppress HPAIV as a result of competition for cell surface receptors or competent cells required for replication [13].…”