In a recent article revealed in Eurosurveillance, researchers offered serological proof of extremely pathogenic avian influenza (HPAI) H5N1 virus an infection in a pet cat and 5 dogs on a rural poultry farm in Italy.
About the infecting virus
This virus first contaminated hens on the identical farm. When Italian authorities quarantined the farm on account of suspicion of an avian influenza outbreak, this farm had 22 poultry animals: two rooster hens, eight geese, two geese, and ten chicks.
They famous that 16 of 18 hens on the farm died. However, the pet dogs/cat didn’t present any medical signs of HPAI an infection.
Reassortment occasions throughout the black-headed gulls-adapted H13 subtype gave rise to the HPAI H5N1 BB genotype in Europe in May 2022. By January 2023, it unfold broadly in black-headed gulls in northern Italy, inflicting mass mortality round Lake Garda.
This genotype additionally brought on seven outbreaks on industrial farms within the Veneto and Emilia Romagna areas. Given its unfold amongst wild birds within the space surrounding the farm, surveyors anticipated detecting the virus because the farm was round 10 km south of Lake Garda.
Sampling for virological and serological investigations
At the time of the primary sampling, i.e., 17 April 2023, surveyors collected nasal swab samples from 10 individuals, together with the proprietor and his 5 relations, three veterinarians, and one employee who did hen culling and corpse disposal.
The second sampling came about six to 9 months later. They sampled the canine twice, although solely collected blood samples, and the cat as soon as.
Further, the researchers used a real-time reverse transcription-polymerase chain response (RT-PCR) focusing on the M gene of AIV to check tracheal and cloacal swab samples of people and birds.
They analyzed samples testing optimistic on this check utilizing two different RT-PCRs directed in direction of the H5 and H7 genomes and neuraminidase subtype and H5 pathotype. Only hen samples examined optimistic for AIV, whereas human, duck, and goose samples examined detrimental.
Further, the crew carried out complete genome sequencing of 1 optimistic pattern derived from hens. Next, they aligned these genomic sequences to intently associated sequences from the worldwide initiative on sharing all influenza knowledge (GISAID) database recognized by way of BLAST search, which revealed that the infecting virus belonged to genotype BB, clade 2.3.4.4b.
Molecular evaluation uncovered an atypical mutation, T271A, in viral protein PB2, which steered this virus tailored to contaminate mammals. Notably, this mutation has by no means been detected in clade 2.3.4.4b H5Nx viruses affecting birds in Europe since 2020 however was answerable for an outbreak in minks (a mammalian species) in Spain.
This remark raises the chance that this virus may need unfold from mammals to birds.
The crew used a set of enzyme-linked immunosorbent assays (ELISAs) to check canine and cat sera, with all assays directed in direction of monoclonal antibodies (mAbs) in opposition to nucleoprotein kind A (NPA), neuraminidases N1, N2, N3 and N7, in addition to hemagglutinins H5, H7.
The crew confirmed the presence and specificity of H5 mAbs utilizing the hemagglutination inhibition (HI) check and by microneutralization (MN) assay based mostly on HPAI-H5N1 and LPAI-H5N3 viruses.
These serological exams detected mAbs in opposition to NPA, H5, and N1 in dogs and the cat sera at each sampling timepoints. Further evaluation revealed sera from all animals besides one canine examined optimistic in HI assay for the H5N1 Gull/23 virus. In the MN assay, sera from all animals had been optimistic for a similar pressure, albeit with larger titers.
The pet animals recording the best HI and MN titers in opposition to the Gull/23 virus additionally scored larger neutralizing titers within the MN assay directed in direction of the Mal/08 virus.
Finally, the crew examined human sera utilizing the identical H5-EL aggressive ELISA used for pets however a modified MN assay to check the pet sera. The check outcomes confirmed all 10 people had been asymptomatic.
Conclusion
The present examine offered serological proof of HPAI H5N1 virus an infection in 5 dogs and one cat on a poultry farm in Italy, highlighting the importance of genetic surveillance for early detection of avian viruses adapting quickly to contaminate mammals with elevated zoonotic potential.
More importantly, complete genomic sequencing of those viruses is required to determine gene mutations correlated with these variations.
