Rapid separation and identification of the subtypes of swine and equine influenza A viruses by electromigration techniques with UV and fluorometric detection

Equines are susceptible to respiratory viruses such as influenza and parainfluenza. Respiratory diseases have adversely impacted economies all over the world. This study was intended to determine the presence of influenza and parainfluenza viruses in unvaccinated horses from some regions of the state of São Paulo, Brazil. Blood serum collected from 72 equines of different towns in this state was tested by hemagglutination inhibition test to detect antibodies for both viruses using the corresponding antigens. About 98.6% (71) and 97.2% (70) of the equines responded with antibody protective titers (≥ 80 HIU/25µL) H7N7 and H3N8 subtypes of influenza A viruses, respectively. All horses (72) also responded with protective titers (≥ 80) HIU/25µL against the parainfluenza virus. The difference between mean antibody titers to H7N7 and H3N8 subtypes of influenza A viruses was not statistically significant (p > 0.05). The mean titers for influenza and parainfluenza viruses, on the other hand, showed a statistically significant difference (p < 0.001). These results indicate a better antibody response from equines to parainfluenza 3 virus than to the equine influenza viruses. No statistically significant differences in the responses against H7N7 and H3N8 subtypes of influenza A and parainfluenza 3 viruses were observed according to the gender (female, male) or the age (≤ 2 to 20 years-old) groups. This study provides evidence of the concomitant presence of two subtypes of the equine influenza A (H7N7 and H3N8) viruses and the parainfluenza 3 virus in equines in Brazil. Thus, it is advisable to vaccinate equines against these respiratory viruses.

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Adaptation of an H7N7 equine influenza A virus in mice

Journal of General Virology ◽

10.1099/vir.0.82411-0 ◽

2007 ◽

Vol 88 (2) ◽

pp. 547-553 ◽

Cited By ~ 54

Author(s):

Kyoko Shinya ◽

Shinji Watanabe ◽

Toshihiro Ito ◽

Noriyuki Kasai ◽

Yoshihiro Kawaoka

Keyword(s):

Protein Expression ◽

Influenza A Virus ◽

Virus Replication ◽

Viral Protein ◽

Influenza A ◽

Animal Species ◽

Influenza A Viruses ◽

Equine Influenza ◽

Viral Protein Expression ◽

Wild Waterfowl

Wild waterfowl are a reservoir for influenza A viruses, which can be transmitted from these birds to other animal species. Occasionally, influenza A viruses are transmitted to other animal species from animals other than wild waterfowl, e.g. an equine influenza virus has been transmitted to dogs and caused outbreaks. To understand the molecular mechanism by which influenza A viruses adapt to a new animal species, the molecular changes involved in the adaptation of an H7N7 equine influenza A virus were studied in mice. Mutations in the mouse-adapted virus mapped to one amino acid change in the PA protein, one in PB2 and two in PB1. Of these mutations, the Glu-to-Lys substitution at position 627 of PB2 (PB2-E627K) increased virulence appreciably. To understand the mechanism of this increased virulence, a recombinant virus expressing a reporter green fluorescent protein was constructed, thus enabling the effect of this mutation on viral protein expression to be tested in the context of virus replication in situ. It was found that the PB2-E627K substitution in this equine virus contributed to increased viral protein expression and virus replication in mouse cells and enhanced brain invasiveness in mice. These results demonstrate that the importance of the PB2-E627K substitution for mouse adaptation, which was identified previously in human H5N1 isolates, extends to equine influenza A virus.

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Mammalian Adaptation of an Avian Influenza A Virus Involves Stepwise Changes in NS1

Journal of Virology ◽

10.1128/jvi.01875-17 ◽

2017 ◽

Vol 92 (5) ◽

Cited By ~ 9

Author(s):

C. Chauché ◽

A. Nogales ◽

H. Zhu ◽

D. Goldfarb ◽

A. I. Ahmad Shanizza ◽

...

Keyword(s):

Influenza Virus ◽

Immune Evasion ◽

Influenza A ◽

Nonstructural Protein ◽

Ns1 Protein ◽

Equine Influenza Virus ◽

Influenza A Viruses ◽

Equine Influenza ◽

Nonstructural Protein 1 ◽

Avian Origin

ABSTRACT Influenza A viruses (IAVs) are common pathogens of birds that occasionally establish endemic infections in mammals. The processes and mechanisms that result in IAV mammalian adaptation are poorly understood. The viral nonstructural 1 (NS1) protein counteracts the interferon (IFN) response, a central component of the host species barrier. We characterized the NS1 proteins of equine influenza virus (EIV), a mammalian IAV lineage of avian origin. We showed that evolutionarily distinct NS1 proteins counteract the IFN response using different and mutually exclusive mechanisms: while the NS1 proteins of early EIVs block general gene expression by binding to cellular polyadenylation-specific factor 30 (CPSF30), NS1 proteins from more evolved EIVs specifically block the induction of IFN-stimulated genes by interfering with the JAK/STAT pathway. These contrasting anti-IFN strategies are associated with two mutations that appeared sequentially and were rapidly selected for during EIV evolution, highlighting the importance of evolutionary processes in immune evasion mechanisms during IAV adaptation. IMPORTANCE Influenza A viruses (IAVs) infect certain avian reservoir species and occasionally transfer to and cause epidemics of infections in some mammalian hosts. However, the processes by which IAVs gain the ability to efficiently infect and transmit in mammals remain unclear. H3N8 equine influenza virus (EIV) is an avian-origin virus that successfully established a new lineage in horses in the early 1960s and is currently circulating worldwide in the equine population. Here, we analyzed the molecular evolution of the virulence factor nonstructural protein 1 (NS1) and show that NS1 proteins from different time periods after EIV emergence counteract the host innate immune response using contrasting strategies, which are associated with two mutations that appeared sequentially during EIV evolution. The results shown here indicate that the interplay between virus evolution and immune evasion plays a key role in IAV mammalian adaptation.

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Long-term adaptation following influenza A virus host shifts results in increased within-host viral fitness due to higher replication rates, broader dissemination within the respiratory epithelium and reduced tissue damage

PLoS Pathogens ◽

10.1371/journal.ppat.1010174 ◽

2021 ◽

Vol 17 (12) ◽

pp. e1010174

Author(s):

Julien A. R. Amat ◽

Veronica Patton ◽

Caroline Chauché ◽

Daniel Goldfarb ◽

Joanna Crispell ◽

...

Keyword(s):

Influenza A ◽

Respiratory Epithelium ◽

Viral Fitness ◽

Equine Influenza Virus ◽

Influenza A Viruses ◽

Virus Genotype ◽

Equine Influenza ◽

Host Shifts ◽

Mammalian Cell Lines

The mechanisms and consequences of genome evolution on viral fitness following host shifts are poorly understood. In addition, viral fitness -the ability of an organism to reproduce and survive- is multifactorial and thus difficult to quantify. Influenza A viruses (IAVs) circulate broadly among wild birds and have jumped into and become endemic in multiple mammalian hosts, including humans, pigs, dogs, seals, and horses. H3N8 equine influenza virus (EIV) is an endemic virus of horses that originated in birds and has been circulating uninterruptedly in equine populations since the early 1960s. Here, we used EIV to quantify changes in infection phenotype associated to viral fitness due to genome-wide changes acquired during long-term adaptation. We performed experimental infections of two mammalian cell lines and equine tracheal explants using the earliest H3N8 EIV isolated (A/equine/Uruguay/63 [EIV/63]), and A/equine/Ohio/2003 (EIV/2003), a monophyletic descendant of EIV/63 isolated 40 years after the emergence of H3N8 EIV. We show that EIV/2003 exhibits increased resistance to interferon, enhanced viral replication, and a more efficient cell-to-cell spread in cells and tissues. Transcriptomics analyses revealed virus-specific responses to each virus, mainly affecting host immunity and inflammation. Image analyses of infected equine respiratory explants showed that despite replicating at higher levels and spreading over larger areas of the respiratory epithelium, EIV/2003 induced milder lesions compared to EIV/63, suggesting that adaptation led to reduced tissue pathogenicity. Our results reveal previously unknown links between virus genotype and the host response to infection, providing new insights on the relationship between virus evolution and fitness.

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Differential sensitivity of human, avian, and equine influenza a viruses to a glycoprotein inhibitor of infection: Selection of receptor specific variants

Virology ◽

10.1016/0042-6822(83)90507-x ◽

1983 ◽

Vol 131 (2) ◽

pp. 394-408 ◽

Cited By ~ 146

Author(s):

Gary N. Rogers ◽

Thomas J. Pritchett ◽

Jeri L. Lane ◽

James C. Paulson

Keyword(s):

Influenza A ◽

Differential Sensitivity ◽

Influenza A Viruses ◽

Equine Influenza ◽

Selection Of

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Equine influenza: a comprehensive review from etiology to treatment

Animal Health Research Reviews ◽

10.1017/s1466252321000050 ◽

2021 ◽

pp. 1-16

Author(s):

Luís Dionísio ◽

Francisco Medeiros ◽

Manuel Pequito ◽

Ana I. Faustino-Rocha

Keyword(s):

Diagnostic Tests ◽

Influenza A ◽

Clinical Signs ◽

Vaccination Status ◽

Upper Respiratory Tract ◽

Influenza A Viruses ◽

Comprehensive Review ◽

Equine Influenza ◽

Rapid Spread ◽

Upper Respiratory

Abstract Influenza is an extremely contagious respiratory disease, which predominantly affects the upper respiratory tract. There are four types of influenza virus, and pigs and chickens are considered two key reservoirs of this virus. Equine influenza (EI) virus was first identified in horses in 1956, in Prague. The influenza A viruses responsible for EI are H7N7 and H3N8. Outbreaks of EI are characterized by their visible and rapid spread, and it has been possible to isolate and characterize H3N8 outbreaks in several countries. The clinical diagnosis of this disease is based on the clinical signs presented by the infected animals, which can be confirmed by performing complementary diagnostic tests. In the diagnosis of EI, in the field, rapid antigen detection tests can be used for a first approach. Treatment is based on the management of the disease and rest for the animal. Regarding the prognosis, it will depend on several factors, such as the animal's vaccination status. One of the important points in this disease is its prevention, which can be done through vaccination. In addition to decreasing the severity of clinical signs and morbidity during outbreaks, vaccination ensures immunity for the animals, reducing the economic impact of this disease.

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