Tissue distribution of human and avian type sialic acid influenza virus receptors in domestic cat

Epidemiology, biosafety, and biosecurity of Avian Influenza: Insights from the East Mediterranean region

The World Organization for Animal Health defines Avian Influenza Virus as a highly infectious disease caused by diverse subtypes that continue to evolve rapidly, impacting poultry species, pet birds, wild birds, non-human mammals, and occasionally humans. The effects of Avian influenza viruses have been recognised as a precursor for serious health concerns among affected birds, poultry, and human populations in the Middle East. Furthermore, low and high pathogenic avian influenza viruses lead to respiratory illness with varying severity, depending on the virus subtype (e.g., H5, H7, H9, etc.). Possible future outbreaks and endemics of newly emerging subtypes are expected to occur, as many studies have reported the emergence of novel mutations and viral subtypes. However, proper surveillance programs and biosecurity applications should be developed, and countries with incapacitated defences against such outbreaks should be encouraged to undergo complete reinstation and reinforcement in their health and research sectors. Public education regarding biosafety and virus prevention is necessary to ensure minimal spread of avian influenza endemic.

The neuropathogenesis of highly pathogenic avian influenza H5Nx viruses in mammalian species including humans

Circulation of highly pathogenic avian influenza (HPAI) H5Nx viruses of the A/Goose/Guangdong/1/96 lineage in birds regularly causes infections of mammals, including humans. In many mammalian species, infections are associated with severe neurological disease, a unique feature of HPAI H5Nx viruses compared with other influenza A viruses. Here, we provide an overview of the neuropathogenesis of HPAI H5Nx virus infection in mammals, centered on three aspects: neuroinvasion, neurotropism, and neurovirulence. We focus on in vitro studies, as well as studies on naturally or experimentally infected mammals. Additionally, we discuss the contribution of viral factors to the neuropathogenesis of HPAI H5Nx virus infections and the efficacy of intervention strategies to prevent neuroinvasion or the development of neurological disease.

A Fatal A/H5N1 Avian Influenza Virus Infection in a Cat in Poland

A European Shorthair male cat, neutered, approximately 6 years of age, was presented to the veterinary clinic due to apathy and anorexia. The cat lived mostly outdoors and was fed raw chicken meat. After 3 days of diagnostic procedures and symptomatic treatment, respiratory distress and neurological signs developed and progressed into epileptic seizures, followed by respiratory and cardiac arrest within the next 3 days. Post-mortem examination revealed necrotic lesions in the liver, lungs, and intestines. Notably, the brain displayed perivascular infiltration of lymphocytes and histiocytes. Few foci of neuronal necrosis in the brain were also confirmed. Microscopic examination of the remaining internal organs was unremarkable. The A/H5N1 virus infection was confirmed using a one-step real-time reverse transcription polymerase chain reaction (RT-qPCR). The disease caused severe neurological and respiratory signs, evidence of consolidations and the presence of numerous B lines, which were detected on lung ultrasound examination; the postmortem findings and detection of A/H5N1 viral RNA in multiple tissues indicated a generalized A/H5N1 virus infection. Moreover, a multidrug-resistant strain of Enterococcus faecium was isolated in pure culture from several internal organs. The source of infection could be exposure to infected birds or their excrements, as well as contaminated raw poultry meat but, in this case, the source of infection could not be identified.

Zoonotic Animal Influenza Virus and Potential Mixing Vessel Hosts

Influenza viruses belong to the family Orthomyxoviridae with a negative-sense, single-stranded segmented RNA genome. They infect a wide range of animals, including humans. From 1918 to 2009, there were four influenza pandemics, which caused millions of casualties. Frequent spillover of animal influenza viruses to humans with or without intermediate hosts poses a serious zoonotic and pandemic threat. The current SARS-CoV-2 pandemic overshadowed the high risk raised by animal influenza viruses, but highlighted the role of wildlife as a reservoir for pandemic viruses. In this review, we summarize the occurrence of animal influenza virus in humans and describe potential mixing vessel or intermediate hosts for zoonotic influenza viruses. While several animal influenza viruses possess a high zoonotic risk (e.g., avian and swine influenza viruses), others are of low to negligible zoonotic potential (e.g., equine, canine, bat and bovine influenza viruses). Transmission can occur directly from animals, particularly poultry and swine, to humans or through reassortant viruses in "mixing vessel" hosts. To date, there are less than 3000 confirmed human infections with avian-origin viruses and less than 7000 subclinical infections documented. Likewise, only a few hundreds of confirmed human cases caused by swine influenza viruses have been reported. Pigs are the historic mixing vessel host for the generation of zoonotic influenza viruses due to the expression of both avian-type and human-type receptors. Nevertheless, there are a number of hosts which carry both types of receptors and can act as a potential mixing vessel host. High vigilance is warranted to prevent the next pandemic caused by animal influenza viruses.

Avian influenza (H5N1) virus, epidemiology and its effects on backyard poultry in Indonesia: a review

Avian influenza (AI) is a zoonotic viral endemic disease that affects poultry, swine, and mammals, including humans. Highly pathogenic avian influenza (HPAI) is caused by influenza type A virus subtypes H5, and H7 which are naturally carried by a wild bird and often affect domestic poultry. Avian influenza (AI) is a major problem worldwide that causes significant economic losses in the poultry sector. Since 2003, the widespread H5N1 HPAI in poultry has led to high mortalities resulting in huge economic losses in the poultry sector in Indonesia. Domestic poultry is a key source of income that contributes to economic growth, both directly and indirectly, by reducing poverty among the people living in rural communities. Furthermore, in many developing countries, including Indonesia, rural people meet a portion of their food needs through backyard poultry. Nevertheless, this sector is strongly affected by biosecurity hazards, particularly in Indonesia by HPAI infections. Avian influenza (AI), subtype H5N1 has zoonotic significance, posing major risks to public health and poultry. Due to close interaction between wild migratory birds and ducks, the domestic poultry sector in Indonesia is directly affected by this virus. This virus continues to be ubiquitous in Indonesia as a result of the unpredictable mutations produced by antigenic drift and shift, which can persist from a few days to several years. In this review, the epidemiology and impact, of highly pathogenic avian influenza H5N1 subtype virus infection on backyard poultry in Indonesia were discussed.

Avian influenza (H5N1) virus, epidemiology and its effects on backyard poultry in Indonesia: a review

Avian influenza (AI) is a zoonotic viral endemic disease that affects poultry, swine, and mammals, including humans. Highly pathogenic avian influenza (HPAI) is caused by influenza type A virus subtypes H5, and H7 which are naturally carried by a wild bird and often affect domestic poultry. Avian influenza (AI) is a major problem worldwide that causes significant economic losses in the poultry sector. Since 2003, the widespread H5N1 HPAI in poultry has led to high mortalities resulting in huge economic losses in the poultry sector in Indonesia. Domestic poultry is a key source of income that contributes to economic growth, both directly and indirectly, by reducing poverty among the people living in rural communities. Furthermore, in many developing countries, including Indonesia, rural people meet a portion of their food needs through backyard poultry. Nevertheless, this sector is strongly affected by biosecurity hazards, particularly in Indonesia by HPAI infections. Avian influenza (AI), subtype H5N1 has zoonotic significance, posing major risks to public health and poultry. Due to close interaction between wild migratory birds and ducks, the domestic poultry sector in Indonesia is directly affected by this virus. This virus continues to be ubiquitous in Indonesia as a result of the unpredictable mutations produced by antigenic drift and shift, which can persist from a few days to several years. In this review, the epidemiology and impact, of highly pathogenic avian influenza H5N1 subtype virus infection on backyard poultry in Indonesia were discussed.

Emergence and Characterization of a Novel Reassortant Canine Influenza Virus Isolated from Cats

Cats are susceptible to a wide range of influenza A viruses (IAV). Furthermore, cats can serve as an intermediate host, and transfer avian influenza virus (AIV) H7N2 to a veterinarian. In this report, a novel reassortant influenza virus, designated A/feline/Jiangsu/HWT/2017 (H3N2), and abbreviated as FIV-HWT-2017, was isolated from nasal swab of a symptomatic cat in Jiangsu province, China. Sequence analysis indicated that, whilst the other seven genes were most similar to the avian-origin canine influenza viruses (CIV H3N2) isolated in China, the NS gene was more closely related to the circulating human influenza virus (H3N2) in the region. Therefore, FIV-HWT-2017 is a reassortant virus. In addition, some mutations were identified, and they were similar to a distinctive CIV H3N2 clade. Whether these cats were infected with the reassortant virus was unknown, however, this random isolation of a reassortant virus indicated that domestic or stray cats were "mixing vessel" for IAV cannot be ruled out. An enhanced surveillance for novel influenza virus should include pet and stray cats.

Efficiency Comparison of a Novel E2 Subunit Vaccine and a Classic C-Strain Vaccine against Classical Swine Fever

Classical swine fever (CSF) is one of the most important viral diseases in swine, causing severe economic losses in the swine industry. In China, CSF is one of the key diseases that needs to be controlled; the government has implemented control measures, and vaccination with C-strain vaccines (C-vacs) has been compulsory since the 1950s. C-vacs do not allow the differentiation of field virus-infected and vaccinated animals (DIVA). In 2012, China proposed a goal of eradicating CSF. Additionally, a baculovirus-expressed E2 subunit vaccine (E2-vac) was licensed in 2018. However, the C-vac and E2-vac characteristics have not been compared. Here, we demonstrate that both the C-vac and E2-vac provide complete protection against CSF in pigs. The E2-vac allows DIVA, and the E2 antibody responses of stimulated pigs are developed earlier and are stronger than the C-vac antibody responses. Therefore, the E2-vac is a new candidate licensed vaccine to completely eradicate CSF on pig farms.

Reverse Zoonosis of COVID-19: Lessons From the 2009 Influenza Pandemic

Over the past decade, pandemics caused by pandemic H1N1 (pH1N1) influenza virus in 2009 and severe acute respiratory syndrome virus type 2 (SARS-CoV-2) in 2019 have emerged. Both are high-impact respiratory pathogens originating from animals. Their wide distribution in the human population subsequently results in an increased risk of human-to-animal transmission: reverse zoonosis. Although there have only been rare reports of reverse zoonosis events associated with the ongoing coronavirus disease 2019 (COVID-19) pandemic from SARS-CoV-2 so far, comparison with the pH1N1 influenza pandemic can provide a better understanding of the possible consequences of such events for public and animal health. The results of our review suggest that similar factors contribute to successful crossing of the host species barriers in both pandemics. Specific risk factors include sufficient interaction between infected humans and recipient animals, suitability of the animal host factors for productive virus infection, and suitability of the animal host population for viral persistence. Of particular concern is virus spread to susceptible animal species, in which group housing and contact network structure could potentially result in an alternative virus reservoir, from which reintroduction into humans can take place. Virus exposure in high-density populations could allow sustained transmission in susceptible animal species. Identification of the risk factors and serological surveillance in SARS-CoV-2-susceptible animal species that are group-housed should help reduce the threat from reverse zoonosis of COVID-19.

Influenza A Virus Infection in Cats and Dogs: A Literature Review in the Light of the "One Health" Concept

Influenza A viruses are amongst the most challenging viruses that threaten both human and animal health. Constantly evolving and crossing species barrier, the emergence of novel zoonotic pathogens is one of the greatest challenges to global health security. During the last decade, considerable attention has been paid to influenza virus infections in dogs, as two canine H3N8 and H3N2 subtypes caused several outbreaks through the United States and Southern Asia, becoming endemic. Cats, even though less documented in the literature, still appear to be susceptible to many avian influenza infections. While influenza epidemics pose a threat to canine and feline health, the risks to humans are largely unknown. Here, we review most recent knowledge of the epidemiology of influenza A viruses in dogs and cats, existing evidences for the abilities of these species to host, sustain intraspecific transmission, and generate novel flu A lineages through genomic reassortment. Such enhanced understanding suggests a need to reinforce surveillance of the role played by companion animals-human interface, in light of the “One Health” concept and the potential emergence of novel zoonotic viruses.

Characterization of a Feline Influenza A(H7N2) Virus

During December 2016-February 2017, influenza A viruses of the H7N2 subtype infected ≈500 cats in animal shelters in New York, NY, USA, indicating virus transmission among cats. A veterinarian who treated the animals also became infected with feline influenza A(H7N2) virus and experienced respiratory symptoms. To understand the pathogenicity and transmissibility of these feline H7N2 viruses in mammals, we characterized them in vitro and in vivo. Feline H7N2 subtype viruses replicated in the respiratory organs of mice, ferrets, and cats without causing severe lesions. Direct contact transmission of feline H7N2 subtype viruses was detected in ferrets and cats; in cats, exposed animals were also infected via respiratory droplet transmission. These results suggest that the feline H7N2 subtype viruses could spread among cats and also infect humans. Outbreaks of the feline H7N2 viruses could, therefore, pose a risk to public health.

Detection of an avian lineage influenza A(H7N2) virus in air and surface samples at a New York City feline quarantine facility

BACKGROUND

In December 2016, an outbreak of low pathogenicity avian influenza (LPAI) A(H7N2) occurred in cats at a New York City animal shelter and quickly spread to other shelters in New York and Pennsylvania. The A(H7N2) virus also spread to an attending veterinarian. In response, 500 cats were transferred from these shelters to a temporary quarantine facility for continued monitoring and treatment.

OBJECTIVES

The objective of this study was to assess the occupational risk of A(H7N2) exposure among emergency response workers at the feline quarantine facility.

METHODS

Aerosol and surface samples were collected from inside and outside the isolation zones of the quarantine facility. Samples were screened for A(H7N2) by quantitative RT-PCR and analyzed in embryonated chicken eggs for infectious virus.

RESULTS

H7N2 virus was detected by RT-PCR in 28 of 29 aerosol samples collected in the high-risk isolation (hot) zone with 70.9% on particles with aerodynamic diameters >4 μm, 27.7% in 1-4 μm, and 1.4% in <1 μm. Seventeen of 22 surface samples from the high-risk isolation zone were also H7N2 positive with an average M1 copy number of 1.3 × 10³ . Passage of aerosol and surface samples in eggs confirmed that infectious virus was present throughout the high-risk zones in the quarantine facility.

CONCLUSIONS

By measuring particle size, distribution, and infectivity, our study suggests that the A(H7N2) virus had the potential to spread by airborne transmission and/or direct contact with viral-laden fomites. These results warranted continued A(H7N2) surveillance and transmission-based precautions during the treatment and care of infected cats.

The NS1 protein of H5N6 feline influenza virus inhibits feline beta interferon response by preventing NF-κB and IRF3 activation

Despite the apparent lack of a feline influenza virus lineage, cats are susceptible to infection by influenza A viruses. Here, we characterized in vitro A/feline/Guangdong/1/2015, an H5N6 avian influenza virus recently isolated from cats. A/feline/Guangdong/1/2015 replicated to high titers and caused CPE in feline kidney cells. We determined that infection with A/feline/Guangdong/1/2015 did not activate the IFN-β promoter, but inhibited it by blocking the activation of NF-κB and IRF3. We also determined that the viral NS1 protein mediated the block, and that the dsRNA binding domain of NS1 was essential to perform this function. In contrast to treatment after infection, cells pretreated with IFN-β suppressed viral replication. Our findings provide an example of an H5N6 influenza virus suppressing IFN production, which might be associated with interspecies transmission of avian influenza viruses to cats.

A Novel A(H7N2) Influenza Virus Isolated from a Veterinarian Caring for Cats in a New York City Animal Shelter Causes Mild Disease and Transmits Poorly in the Ferret Model

In December 2016, a low-pathogenic avian influenza (LPAI) A(H7N2) virus was identified to be the causative source of an outbreak in a cat shelter in New York City, which subsequently spread to multiple shelters in the states of New York and Pennsylvania. One person with occupational exposure to infected cats became infected with the virus, representing the first LPAI H7N2 virus infection in a human in North America since 2003. Considering the close contact that frequently occurs between companion animals and humans, it was critical to assess the relative risk of this novel virus to public health. The virus isolated from the human case, A/New York/108/2016 (NY/108), caused mild and transient illness in ferrets and mice but did not transmit to naive cohoused ferrets following traditional or aerosol-based inoculation methods. The environmental persistence of NY/108 virus was generally comparable to that of other LPAI H7N2 viruses. However, NY/108 virus replicated in human bronchial epithelial cells with an increased efficiency compared with that of previously isolated H7N2 viruses. Furthermore, the novel H7N2 virus was found to utilize a relatively lower pH for hemagglutinin activation, similar to human influenza viruses. Our data suggest that the LPAI H7N2 virus requires further adaptation before representing a substantial threat to public health. However, the reemergence of an LPAI H7N2 virus in the northeastern United States underscores the need for continuous surveillance of emerging zoonotic influenza viruses inclusive of mammalian species, such as domestic felines, that are not commonly considered intermediate hosts for avian influenza viruses.IMPORTANCE Avian influenza viruses are capable of crossing the species barrier to infect mammals, an event of public health concern due to the potential acquisition of a pandemic phenotype. In December 2016, an H7N2 virus caused an outbreak in cats in multiple animal shelters in New York State. This was the first detection of this virus in the northeastern United States in over a decade and the first documented infection of a felid with an H7N2 virus. A veterinarian became infected following occupational exposure to H7N2 virus-infected cats, necessitating the evaluation of this virus for its capacity to cause disease in mammals. While the H7N2 virus was associated with mild illness in mice and ferrets and did not spread well between ferrets, it nonetheless possessed several markers of virulence for mammals. These data highlight the promiscuity of influenza viruses and the need for diligent surveillance across multiple species to quickly identify an emerging strain with pandemic potential.

Genetic characterization of novel reassortant H5N6-subtype influenza viruses isolated from cats in eastern China

Cats are susceptible to influenza A viruses and therefore may act as transmission vectors within households, posing a potential public health concern. Two novel reassortant H5N6 influenza viruses were isolated from cats in Zhejiang Province, Eastern China, in 2016. Both viruses were characterized by whole-genome sequencing with subsequent phylogenetic analysis and genetic comparison. Phylogenetic analysis showed that these viruses received their genes from H5N6, H9N2, and H7N9 influenza viruses isolated from China. These H5N6 viruses were able to replicate in mice without prior adaptation. Our results show that continued circulation of these viruses could endanger humans.

Equine influenza A(H3N8) virus infection in cats

Interspecies transmission of equine influenza A(H3N8) virus has resulted in establishment of a canine influenza virus. To determine if something similar could happen with cats, we experimentally infected 14 cats with the equine influenza A(H3N8) virus. All showed clinical signs, shed virus, and transmitted the virus to a contact cohort.

Genetic Adaptation of Influenza A Viruses in Domestic Animals and Their Potential Role in Interspecies Transmission: A Literature Review

In December 2011, the European Food Safety Authority awarded a Grant for the implementation of the FLURISK project. The main objective of FLURISK was the development of an epidemiological and virological evidence-based influenza risk assessment framework (IRAF) to assess influenza A virus strains circulating in the animal population according to their potential to cross the species barrier and cause infections in humans. With the purpose of gathering virological data to include in the IRAF, a literature review was conducted and key findings are presented here. Several adaptive traits have been identified in influenza viruses infecting domestic animals and a significance of these adaptations for the emergence of zoonotic influenza, such as shift in receptor preference and mutations in the replication proteins, has been hypothesized. Nonetheless, and despite several decades of research, a comprehensive understanding of the conditions that facilitate interspecies transmission is still lacking. This has been hampered by the intrinsic difficulties of the subject and the complexity of correlating environmental, viral and host factors. Finding the most suitable and feasible way of investigating these factors in laboratory settings represents another challenge. The majority of the studies identified through this review focus on only a subset of species, subtypes and genes, such as influenza in avian species and avian influenza viruses adapting to humans, especially in the context of highly pathogenic avian influenza H5N1. Further research applying a holistic approach and investigating the broader influenza genetic spectrum is urgently needed in the field of genetic adaptation of influenza A viruses.

Serological evidence of avian influenza virus and canine influenza virus infections among stray cats in live poultry markets, China

From January 2010 to January 2012, we collected sera samples from 700 stray cats living in close proximity to poultry farms or poultry markets in 4 provinces in China. A number of cats had evidence of avian and canine influenza virus infection: avian H9N2 [24 by HI ≥1:20 and 16 by microneutralization (MN) assay ≥1:80]; avian H5N1 (9 by HI ≥1:20 and 3 by MN assay ≥1:80) and canine H3N2 (32 by HI ≥1:20 and 18 by MN ≥1:80). Bivariate analyses revealed that cats sampled near live poultry markets and cats with influenza-like-illness were at increased risk of having elevated antibody titers by HI against avian H9N2, avian H5N1, or canine H3N2 viruses. Hence, cats may play a very important role in the ecology of novel influenza viruses and periodic epidemiological surveillance for novel influenza infections among stray cats could serve as an early warning system for human threats.