Are all avian influenza outbreaks in poultry the same? The predicted impact of poultry species and virus subtype

AIMS

Outbreaks of avian influenza in poultry farms are currently increasing in frequency, with devastating consequences for animal welfare, farmers and supply chains. Some studies have documented the direct spread of the avian influenza virus between farms. Prevention of spread between farms relies on biosecurity surveillance and control measures. However, the evolution of an outbreak on a farm might vary depending on the virus strain and poultry species involved; this would have important implications for surveillance systems, epidemiological investigations and control measures.

METHODS AND RESULTS

In this study, we utilized existing parameter estimates from the literature to evaluate the predicted course of an epidemic in a standard poultry flock with 10,000 birds. We used a stochastic SEIR simulation model to simulate outbreaks in different species and with different virus subtypes. The simulations predicted large differences in the duration and severity of outbreaks, depending on the virus subtypes. For both turkeys and chickens, outbreaks with HPAI were of shorter duration than outbreaks with LPAI. In outbreaks involving the infection of chickens with different virus subtypes, the shortest epidemic involved H7N7 and HPAIV H5N1 (median duration of 9 and 17 days, respectively) and the longest involved H5N2 (median duration of 68 days). The most severe outbreaks (number of chickens infected) were predicted for H5N1, H7N1 and H7N3 virus subtypes, and the least severe for H5N2 and H7N7, in which outbreaks for the latter subtype were predicted to develop most slowly.

CONCLUSIONS

These simulation results suggest that surveillance of certain subtypes of avian influenza virus, in chicken flocks in particular, needs to be sensitive and timely if infection is to be detected with sufficient time to implement control measures. The variability in the predictions highlights that avian influenza outbreaks are different in severity, speed and duration, so surveillance and disease response need to be nuanced and fit the specific context of poultry species and virus subtypes.

Genetic and virological characteristics of a reassortant avian influenza A H6N1 virus isolated from wild birds at a live-bird market in Egypt

The first detection of a human infection with avian influenza A/H6N1 virus in Taiwan in 2013 has raised concerns about this virus. During our routine surveillance of avian influenza viruses (AIVs) in live-bird markets in Egypt, an H6N1 virus was isolated from a garganey duck and was characterized. Phylogenetic analysis indicated that the Egyptian H6N1 strain A/Garganey/Egypt/20869C/2022(H6N1) has a unique genomic constellation, with gene segments inherited from different subtypes (H5N1, H3N8, H7N3, H6N1, and H10N1) that have been detected previously in AIVs from Egypt and some Eurasian countries. We examined the replication of kinetics of this virus in different mammalian cell lines (A549, MDCK, and Vero cells) and compared its pathogenicity to that of the ancestral H6N1 virus A/Quail/HK/421/2002(H6N1). The Egyptian H6N1 virus replicated efficiently in C57BL/6 mice without prior adaptation and grew faster and reached higher titers than in A549 cells than the ancestral strain. These results show that reassortant H6 AIVs might pose a potential threat to human health and highlight the need to continue surveillance of H6 AIVs circulating in nature.

Simultaneous detection of multiple influenza virus subtypes based on microbead-encoded microfluidic chip

Influenza virus, existing many subtypes, causes a huge risk of people health and life. Different subtypes bring a huge challenge for detection and treatment, thus simultaneous detection of multiple influenza virus subtypes plays a key role in fight against this disease. In this work, three kinds of influenza virus subtypes are one-step detection based on microbead-encoded microfluidic chip. HIN1, H3N2 and H7N3 were simultaneously captured only by microbeads of different magnetism and sizes, and they were further treated by magnetic separation and enriched through the magnetism and size-dependent microfluidic structure. Different subtypes of influenza virus could be linearly encoded in different detection zones of microfluidic chip according to microbeads of magnetism and size differences. With the high-brightness quantum dots (QDs) as label, the enriched fluorescence detection signals were further read online from linearly encoded strips, obtaining high sensitivity with detection limit of HIN1, H3N2, H7N3 about 2.2 ng/mL, 3.4 ng/mL and 2.9 ng/mL. Moreover, a visual operation interface, microcontroller unit and two-way syringe pump were consisted of a miniaturized detection device, improving the detection process automation. And this assay showed strong specificity. This method improves a new way of multiple pathogens detection using microbead-encoded technologies in the microfluidic chip.

XiaoEr LianHuaQinqGan alleviates viral pneumonia in mice infected by influenza A and respiratory syncytial viruses

CONTEXT

Xiaoer lianhuaqinqgan (XELH), developed based on Lianhua Qingwen (LHQW) prescription, contains 13 traditional Chinese medicines. It has completed the investigational new drug application to treat respiratory viral infections in children in China.

OBJECTIVE

This study demonstrates the pharmacological effects of XELH against viral pneumonia.

MATERIALS AND METHODS

The antiviral and anti-inflammatory effects of XELH were investigated in vitro using H3N2-infected A549 and LPS-stimulated RAW264.7 cells and in vivo using BALB/c mice models of influenza A virus (H3N2) and respiratory syncytial virus (RSV)-infection. Mice were divided into 7 groups (n = 20): Control, Model, LHQW (0.5 g/kg), XELH-low (2 g/kg), XELH-medium (4 g/kg), XELH-high (8 g/kg), and positive drug (20 mg/kg oseltamivir or 60 mg/kg ribavirin) groups. The anti-inflammatory effects of XELH were tested in a rat model of LPS-induced fever and a mouse model of xylene-induced ear edoema.

RESULTS

In vitro, XELH inhibited the pro-inflammatory cytokines and replication of H1N1, H3N2, H1N1, FluB, H9N2, H6N2, H7N3, RSV, and HCoV-229E viruses, with (IC₅₀ 47.4, 114, 79, 250, 99.2, 170, 79, 62.5, and 93 μg/mL, respectively). In vivo, XELH reduced weight loss and lung index, inhibited viral replication and macrophage M1 polarization, ameliorated lung damage, decreased inflammatory cell infiltration and pro-inflammatory cytokines expression in lung tissues, and increased the CD4⁺/CD8⁺ ratio. XELH inhibited LPS-induced fever in rats and xylene-induced ear edoema in mice.

CONCLUSION

XELH efficacy partially depends on integrated immunoregulatory effects. XELH is a promising therapeutic option against childhood respiratory viral infections.

An inactivated multivalent influenza A virus vaccine is broadly protective in mice and ferrets

Influenza A viruses (IAVs) present major public health threats from annual seasonal epidemics and pandemics and from viruses adapted to a variety of animals including poultry, pigs, and horses. Vaccines that broadly protect against all such IAVs, so-called "universal" influenza vaccines, do not currently exist but are urgently needed. Here, we demonstrated that an inactivated, multivalent whole-virus vaccine, delivered intramuscularly or intranasally, was broadly protective against challenges with multiple IAV hemagglutinin and neuraminidase subtypes in both mice and ferrets. The vaccine is composed of four β-propiolactone-inactivated low-pathogenicity avian IAV subtypes of H1N9, H3N8, H5N1, and H7N3. Vaccinated mice and ferrets demonstrated substantial protection against a variety of IAVs, including the 1918 H1N1 strain, the highly pathogenic avian H5N8 strain, and H7N9. We also observed protection against challenge with antigenically variable and heterosubtypic avian, swine, and human viruses. Compared to control animals, vaccinated mice and ferrets demonstrated marked reductions in viral titers, lung pathology, and host inflammatory responses. This vaccine approach indicates the feasibility of eliciting broad, heterosubtypic IAV protection and identifies a promising candidate for influenza vaccine clinical development.

Triazavirin might be the new hope to fight Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)

Since the beginning of the outbreak, a large number of clinical trials have been registered worldwide, and thousands of drugs have been investigated to face new health emergency of highly contagious COVID-19 caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Drug repurposing, i.e., utilizing an approved drug for a different indication, offers a time- and cost-efficient alternative for making new (relevant) therapies available to physicians and patients. Considering given strategy, many approved and investigational antiviral compounds, alone or in various relevant combinations, used in the past to fight Severe Acute Respiratory Syndrome Coronavirus-1, Middle East Respiratory Syndrome Coronavirus, Human Immunodeficiency Virus type 1, or Influenza viruses are being evaluated against the SARS-CoV-2. Triazavirin (TZV), a non-toxic broad--spectrum antiviral compound, is efficient against various strains of the Influenza A virus (Influenza Virus A, Orthomyxoviridae), i.e., swine flu (H1N1, or H3N2), avian influenza (H5N1, H5N2, H9N2, or highly pathogenic H7N3 strain), Influenza B virus (Influenza Virus B, Orthomyxoviridae), Respiratory Syncytial Virus (Orthopneumovirus, Pneumoviridae), Tick-Borne Encephalitis Virus (known as Forest-Spring Encephalitis Virus; Flavivirus, Flaviviridae), West Nile Virus (Flavivirus, Flavaviridae), Rift Valley Fever Virus (Phlebovirus, Bunyaviridae), and Herpes viruses (Simplexviruses, Herpesviridae) as well. In regard to COVID-19, the molecule probably reduced inflammatory reactions, thus limiting the damage to vital organs and reducing the need for therapeutic support, respectively. In addition, in silico computational methods indicated relatively satisfactory binding affinities of the TZV ligand to both structural (E)- and (S)-proteins, non-structural 3-chymotrypsin-like protease (3-CLpro) of SARS-CoV-2 as well as human angiotensin-I converting enzyme-2 (ACE-2). The interactions between TZV and given viral structures or the ACE-2 receptor for SARS-CoV-2 might effectively block both the entry of the pathogen into a host cell and its replication. Promising treatment patterns of COVID-19 positive patients might be also based on a suitable combination of a membrane fusion inhibitor (umifenovir, for example) with viral RNA synthesis and replication inhibitor (TZV).

Highly Pathogenic Avian Influenza A(H7N3) Virus in Poultry, United States, 2020

An outbreak of low-pathogenicity avian influenza A(H7N3) virus of North American wild bird lineage occurred on commercial turkey farms in North Carolina and South Carolina, USA, during March-April 2020. The virus mutated to the highly pathogenic form in 1 house on 1 farm via recombination with host 28S rRNA.

Communication of Scientific Uncertainty about a Novel Pandemic Health Threat: Ambiguity Aversion and Its Mechanisms

Communicating scientific uncertainty about public health threats is ethically desirable but challenging due to its tendency to promote avoidance of choice options with unknown probabilities-a phenomenon known as "ambiguity aversion." This study examined this phenomenon's potential magnitude, its responses to different communication strategies, and its mechanisms. In a factorial experiment, 2701 adult laypersons in Spain read one of three versions of a hypothetical newspaper article describing a pandemic vaccine-preventable disease (VPD), but varying in scientific uncertainty about VPD risk and vaccine effectiveness: No-Uncertainty, Uncertainty, and Normalized-Uncertainty (emphasizing its expected nature). Vaccination intentions were lower for the Uncertainty and Normalized-Uncertainty groups compared to the No-Uncertainty group, consistent with ambiguity aversion; Uncertainty and Normalized-Uncertainty groups did not differ. Ambiguity-averse responses were moderated by health literacy and mediated by perceptions of vaccine effectiveness, VPD likelihood, and VPD severity. Communicating scientific uncertainty about public health threats warrants caution and further research to elucidate its outcomes, mechanisms, and management.

Prevalence and control of H7 avian influenza viruses in birds and humans

The H7 subtype HA gene has been found in combination with all nine NA subtype genes. Most exhibit low pathogenicity and only rarely high pathogenicity in poultry (and humans). During the past few years infections of poultry and humans with H7 subtypes have increased markedly. This review summarizes the emergence of avian influenza virus H7 subtypes in birds and humans, and the possibilities of its control in poultry. All H7Nx combinations were reported from wild birds, the natural reservoir of the virus. Geographically, the most prevalent subtype is H7N7, which is endemic in wild birds in Europe and was frequently reported in domestic poultry, whereas subtype H7N3 is mostly isolated from the Americas. In humans, mild to fatal infections were caused by subtypes H7N2, H7N3, H7N7 and H7N9. While infections of humans have been associated mostly with exposure to domestic poultry, infections of poultry have been linked to wild birds or live-bird markets. Generally, depopulation of infected poultry was the main control tool; however, inactivated vaccines were also used. In contrast to recent cases caused by subtype H7N9, human infections were usually self-limiting and rarely required antiviral medication. Close genetic and antigenic relatedness of H7 viruses of different origins may be helpful in development of universal vaccines and diagnostics for both animals and humans. Due to the wide spread of H7 viruses and their zoonotic importance more research is required to better understand the epidemiology, pathobiology and virulence determinants of these viruses and to develop improved control tools.

Contact structure and potential risk factors for avian influenza transmission among open-sided chicken farms in Kamalia, an important poultry rearing area of Pakistan

Since 1994, the domestic poultry in Pakistan has experienced several outbreaks due to avian influenza viruses of subtypes H7N3, H5N1, and H9N2. This paper reveals horizontal contacts and potential risk factors for the spread of avian influenza infection between open-sided chicken farms in Kamalia, a sub-district of Punjab province. Between April and June 2009, an interview-based questionnaire was administered to a sample of 78 growers. The survey identified the following potential biosecurity risks for outbreak propagation: i) short buffer distances between farms, ii) disposal of carcasses and other organic wastes into the environment, iii) entry of feral birds into poultry sheds, iv) visits of poultry farmers to possible cross-contamination sites, v) absence of boundary walls, vi) incomplete biosecurity on high-risk visitors (i. e. those going inside the poultry houses), essential vehicles and equipment used by vaccination crews vii) visits of intermediaries and service providers and, viii) sharing of egg trays between farms at production. For most of the variables, there was no significant difference between the broiler and layer type of farms (p < or = 0.05). The risk of an extensive outbreak in Kamalia was concluded to be due to its high poultry density, ubiquitous small-scale, market-oriented poultry production with medium to low biosecurity, and the affiliation of the farmers to multiple service providers. To reduce the risk of having an outbreak, farm-specific biosecurity gaps should be identified and appropriate action taken to close these gaps. Improvement in biosecurity and targeted surveillance are therefore considered critical to limit the spread of infection should an outbreak occur.

How backyard poultry flocks influence the effort required to curtail avian influenza epidemics in commercial poultry flocks

This paper summarizes the evidence that the contribution of backyard poultry flocks to the on-going transmission dynamics of an avian influenza epidemic in commercial flocks is modest at best. Nevertheless, while disease control strategies need not involve the backyard flocks, an analysis of the contribution of each element of the next generation matrix to the basic reproduction number indicates that models which ignores the contribution of backyard flocks in estimating the effort required of strategies focused one host type (e.g. commercial flocks only) necessarily underestimate the level of effort to an extent that may matter to policy makers.