Clinical and molecular epidemiology of influenza viruses from Romanian patients hospitalized during the 2019/20 season

Two main mechanisms contribute to the continuous evolution of influenza viruses: accumulation of mutations in the hemagglutinin and neuraminidase genes (antigenic drift) and genetic re-assortments (antigenic shift). Epidemiological surveillance is important in identifying new genetic variants of influenza viruses with potentially increased pathogenicity and transmissibility. In order to characterize the 2019/20 influenza epidemic in Romania, 1042 respiratory samples were collected from consecutive patients hospitalized with acute respiratory infections in the National Institute for Infectious Diseases “Prof. Dr. Matei Balș”, Bucharest Romania and tested for influenza A virus, influenza B virus and respiratory syncytial virus (RSV) by real-time PCR. Out of them, 516 cases were positive for influenza, with relatively equal distribution of influenza A and B. Two patients had influenza A and B co-infection and 8 patients had influenza-RSV co-infection. The most severe cases, requiring supplemental oxygen administration or intensive care, and the most deaths were reported in patients aged 65 years and over. Subtyping showed the predominance of A(H3N2) compared to A(H1N1)pdm09 pdm09 (60.4% and 39.6% of all subtyped influenza A isolates, respectively), and the circulation of Victoria B lineage only. Influenza B started to circulate first (week 47/2019), with influenza A appearing slightly later (week 50/2019), followed by continued co-circulation of A and B viruses throughout the season. Sixty-eight samples, selected to cover the entire influenza season and all circulating viral types, were analysed by next generation sequencing (NGS). All A(H1N1)pdm09 sequences identified during this season in Romania were clustered in the 6b1.A clade (sub-clades: 6b1.A.183P -5a and 6b1.A.187A). For most A(H1N1)pdm09 sequences, the dominant epitope was Sb (pepitope = 0.25), reducing the vaccine efficacy by approximately 60%. According to phylogenetic analysis, influenza A(H3N2) strains circulating in this season belonged predominantly to clade 3C.3A, with only few sequences in clade 3C.2A1b. These 3C.2A1b sequences, two of which belonged to vaccinated patients, harbored mutations in antigenic sites leading to potential reduction of vaccine efficacy. Phylogenetic analysis of influenza B, lineage Victoria, sequences showed that the circulating strains belonged to clade V1A3. As compared to the other viral types, fewer mutations were observed in B/Victoria strains, with limited impact on vaccine efficiency based on estimations.

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Serological studies of influenza viruses in pigs in Great Britain 1991–2

Epidemiology and Infection ◽

10.1017/s0950268800052225 ◽

1995 ◽

Vol 114 (3) ◽

pp. 511-520 ◽

Cited By ~ 31

Author(s):

I. H. Brown ◽

P. A. Harris ◽

D. J. Alexander

Keyword(s):

Great Britain ◽

Influenza A ◽

H1n1 Virus ◽

Haemagglutination Inhibition ◽

Influenza Viruses ◽

Antigenic Drift ◽

H3n2 Virus ◽

Influenza B Virus ◽

Influenza B ◽

Influenza A Viruses

SUMMARYSamples from a sow serum bank representative of the pig population of Great Britain collected during 1991–2, were examined for antibodies to influenza A, B and C viruses, using viruses which had been isolated from a variety of hosts. For influenza A viruses there was evidence of the continued circulation of ‘classical swine’ H1N1 virus (26%) seroprevalence), and human H3N2 viruses (39%) which are antigenically most closely-related to A/Port Chalmers/1/73 virus. In addition antibodies were detected to A/swine/England/201635/92 (8%), a strain of H3N2 virus which appears to have arisen by antigenic drift from conventional H3N2 swine strains. Specific antibodies (2%) were detected to an H1N1 virus (A/swine/England/195852/92) related most closely to avian H1N1 strains. In tests with human H1N1 and H3N2 viruses, excluding isolates from pigs, the highest seroprevalence was detected to the prevailing strains from the human population. Serological tests with avian H4 and H10, human H2, equine 1 and 2 influenza A viruses were all negative. Seven pigs seropositive by haemagglutination-inhibition, virus neutralization and immunoblotting assays for antibody to influenza B virus, were randomly distributed geographically suggesting that influenza B viruses may be transmitted to pigs but fail to spread. The seroprevalence to influenza C viruses was 9·9% indicating that these viruses are widespread in pigs. These results provide further evidence that the pig can be infected by a number of influenza viruses, some of which may have significance in the epidemiology of human influenza.

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Molecular Characterization of Influenza A Viruses Detected in Children Attending Yangon Children’s Hospital, 2016

Myanmar Health Sciences Research Journal ◽

10.34299/mhsrj.00925 ◽

2019 ◽

Vol 31 (1) ◽

pp. 72-80

Keyword(s):

Phylogenetic Analysis ◽

Influenza A Virus ◽

Influenza A ◽

Epidemiological Studies ◽

Influenza Viruses ◽

Influenza B Virus ◽

Influenza B ◽

Influenza A Viruses ◽

B Virus ◽

Na Gene

Sequence analysis of the influenza virus strains is important for molecular epidemiological studies and evolutional studies of influenza viruses as well as for the assessment of vaccine effectiveness. The aim of this study was to determine and characterize predominant subtype of influenza A viruses among children attending Yangon Children’s Hospital (YCH). It was a cross-sectional descriptive study conducted at YCH. Nasopharyngeal swabs were collected from 153 children who attended the hospital due to influenza-like illness (ILI) during January-December, 2016. Viral RNA was extracted by QIAamp® Viral Mini Kit. Matrix genes of influenza A and influenza B virus were detected by multiplex Reverse TranscriptionPolymerase Chain Reaction (RT-PCR). Influenza A virus matrix gene positive samples were subjected to subtyping. Predominant subtypes were subjected to sequencing and phylogenetic analysis of their HA gene and neuraminidase (NA) gene. Influenza viruses were detected in about 14% of children with ILI. Among them, 55% showed influenza A virus positive and 45% showed influenza B virus positive. Influenza A (H3N2) virus was found to be predominant among influenza A virus positive children accounting for 83.4%. There was one case (8.3%) of influenza A (H1N1) pdm09 virus and one case (8.3%) of unsubtyped influenza A virus. Phylogenetic analysis of HA and NA gene of two Myanmar strains of H3N2 subtype revealed that they belonged to clade 3C.2a1. They had 99.3-99.4% nucleotide identity with A/Hong Kong/ 4801/2014, vaccine strain of H3N2 subtype, that was contained in southern hemisphere influenza vaccine for 2016 and northern hemisphere vaccine for 2016-2017 season. This study generated information useful for the assessment of influenza outbreaks, selection of upcoming vaccine strains and further evolutionary and epidemiological studies on influenza viruses.

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Sensitivity of influenza viruses to specific drugs in Russia during 2017−2020. The rare finds and perspective antivirals

Epidemiology and Infectious Diseases (Russian Journal) ◽

10.17816/eid46440 ◽

2020 ◽

Vol 25 (2) ◽

pp. 65-77

Author(s):

Natalia V. Breslav ◽

Kirill G. Krasnoslobotsev ◽

Evgeniya A. Mukasheva ◽

Elena S. Kirillova ◽

Alexandra G. Rosatkevich ◽

...

Keyword(s):

Influenza A ◽

Influenza Viruses ◽

Epidemiological Surveillance ◽

Influenza B Virus ◽

Influenza B ◽

Neuraminidase Inhibitors ◽

Chemotherapy Drugs ◽

Pdm09 Virus ◽

Severe Acute Respiratory Infection ◽

Influenza A H1n1

BACKGROUND: The article presents the results of studying the effectiveness of anti-influenza drugs in Russia in the period 20172020. The sensitivity of circulating strains of influenza viruses A(H1N1)pdm09, A(H3N2) and B to neuraminidase inhibitors oseltamivir, zanamivir and rimantadine was determined. The analysis of scientific articles by both domestic and foreign researchers on new promising chemotherapy drugs for influenza viruses was carried out. AIMS: study of the sensitivity of influenza viruses circulating strains to specific anti-influenza drugs in the framework of monitoring in the period 20172020. MATERIALS AND METHODS: The study was conducted within the framework of epidemiological surveillance of the influenza viruses circulation using the collection of the influenza etiology and epidemiology laboratory with the following criteria for selecting strains isolated from pregnant women, patients with complicated flu infection and severe acute respiratory infection (SARI), lethal outcomes, as well as patients undergoing treatment with specific drugs. Virological, immunological, and molecular genetic methods were used in the study, and following drugs substances were used: oseltamivir carboxylate, zanamivir, and rimantadine. RESULTS: For the period 20172020, the sensitivity of 541 influenza A and B viruses epidemic strains to anti-influenza drugs was studied. Most of the studied strains remained sensitive to neuraminidase inhibitors. The exceptions were: in 2017/2018 5 strains of the influenza A(H1N1)pdm09 virus resistant to oseltamivir and 2 strains of the influenza B virus, one with reduced sensitivity to oseltamivir, the second to zanamivir; in 2019/2020 influenza A(H1N1)pdm09 virus strain with reduced sensitivity to both drugs. In the 2018/2019 season, an influenza A/Moscow/246/2018 A(H1N1)pdm09 strain was found to be sensitive to rimantadine. CONCLUSIONS: The main and most common genetic markers of influenza viruses resistance to specific drugs are: for oseltamivir substitution H274Y in the influenza A(H1N1)pdm09 virus NA; for rimantadine substitution S31N in the influenza A(H1N1)pdm09 and A(H3N2) viruses M2 protein. Taking into account the low frequency of strains with reduced sensitivity to drugs with antineuraminidase activity, can confidently approve that they remain the drugs of choice for the treatment and prevention of influenza infection.

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Influenza

10.1093/med/9780198570028.003.0037 ◽

2011 ◽

Author(s):

D. J. Alexander ◽

N. Phin ◽

M. Zuckerman

Keyword(s):

Sialic Acid ◽

Human Population ◽

Influenza A ◽

Influenza Viruses ◽

Antigenic Drift ◽

Host Cells ◽

Influenza B Virus ◽

Influenza B ◽

Human Populations ◽

Influenza A Viruses

Influenza is a highly infectious, acute illness which has affected humans and animals since ancient times. Influenza viruses form the Orthomyxoviridae family and are grouped into types A, B, and C on the basis of the antigenic nature of the internal nucleocapsid or the matrix protein. Infl uenza A viruses infect a large variety of animal species, including humans, pigs, horses, sea mammals, and birds, occasionally producing devastating pandemics in humans, such as in 1918 when it has been estimated that between 50–100 million deaths occurred worldwide.There are two important viral surface glycoproteins, the haemagglutinin (HA) and neuraminidase (NA). The HA binds to sialic acid receptors on the membrane of host cells and is the primary antigen against which a host’s antibody response is targeted. The NA cleaves the sialic acid bond attaching new viral particles to the cell membrane of host cells allowing their release. The NA is also the target of the neuraminidase inhibitor class of antiviral agents that include oseltamivir and zanamivir and newer agents such as peramivir. Both these glycoproteins are important antigens for inducing protective immunity in the host and therefore show the greatest variation.Influenza A viruses are classified into 16 antigenically distinct HA (H1–16) and 9 NA subtypes (N1–9). Although viruses of relatively few subtype combinations have been isolated from mammalian species, all subtypes, in most combinations, have been isolated from birds. Each virus possesses one HA and one NA subtype.Last century, the sudden emergence of antigenically different strains in humans, termed antigenic shift, occurred on three occasions, 1918 (H1N1), 1957 (H2N2) and 1968 (H3N2), resulting in pandemics. The frequent epidemics that occur between the pandemics are as a result of gradual antigenic change in the prevalent virus, termed antigenic drift. Epidemics throughout the world occur in the human population due to infection with influenza A viruses, such as H1N1 and H3N2 subtypes, or with influenza B virus. Phylogenetic studies have led to the suggestion that aquatic birds that show no signs of disease could be the source of many influenza A viruses in other species. The 1918 H1N1 pandemic strain is thought to have arisen as a result of spontaneous mutations within an avian H1N1 virus. However, most pandemic strains, such as the 1957 H2N2, 1968 H3N2 and 2009 pandemic H1N1, are considered to have emerged by genetic re-assortment of the segmented RNA genome of the virus, with the avian and human influenza A viruses infecting the same host.Influenza viruses do not pass readily between humans and birds but transmission between humans and other animals has been demonstrated. This has led to the suggestion that the proposed reassortment of human and avian influenza viruses takes place in an intermediate animal with subsequent infection of the human population. Pigs have been considered the leading contender for the role of intermediary because they may serve as hosts for productive infections of both avian and human viruses, and there is good evidence that they have been involved in interspecies transmission of influenza viruses; particularly the spread of H1N1 viruses to humans. Apart from public health measures related to the rapid identification of cases and isolation. The main control measures for influenza virus infections in human populations involves immunization and antiviral prophylaxis or treatment.

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Molecular Characterization of Seasonal Influenza A and B from Hospitalized Patients in Thailand in 2018–2019

Viruses ◽

10.3390/v13060977 ◽

2021 ◽

Vol 13 (6) ◽

pp. 977

Author(s):

Kobporn Boonnak ◽

Chayasin Mansanguan ◽

Dennis Schuerch ◽

Usa Boonyuen ◽

Hatairat Lerdsamran ◽

...

Keyword(s):

Amino Acid ◽

Influenza A ◽

Seasonal Influenza ◽

Influenza Viruses ◽

Surface Proteins ◽

Antigenic Drift ◽

Influenza B ◽

Receptor Binding Site ◽

Antigenic Sites ◽

Ha Protein

Influenza viruses continue to be a major public health threat due to the possible emergence of more virulent influenza virus strains resulting from dynamic changes in virus adaptability, consequent of functional mutations and antigenic drift in surface proteins, especially hemagglutinin (HA) and neuraminidase (NA). In this study, we describe the genetic and evolutionary characteristics of H1N1, H3N2, and influenza B strains detected in severe cases of seasonal influenza in Thailand from 2018 to 2019. We genetically characterized seven A/H1N1 isolates, seven A/H3N2 isolates, and six influenza B isolates. Five of the seven A/H1N1 viruses were found to belong to clade 6B.1 and were antigenically similar to A/Switzerland/3330/2017 (H1N1), whereas two isolates belonged to clade 6B.1A1 and clustered with A/Brisbane/02/2018 (H1N1). Interestingly, we observed additional mutations at antigenic sites (S91R, S181T, T202I) as well as a unique mutation at a receptor binding site (S200P). Three-dimensional (3D) protein structure analysis of hemagglutinin protein reveals that this unique mutation may lead to the altered binding of the HA protein to a sialic acid receptor. A/H3N2 isolates were found to belong to clade 3C.2a2 and 3C.2a1b, clustering with A/Switzerland/8060/2017 (H3N2) and A/South Australia/34/2019 (H3N2), respectively. Amino acid sequence analysis revealed 10 mutations at antigenic sites including T144A/I, T151K, Q213R, S214P, T176K, D69N, Q277R, N137K, N187K, and E78K/G. All influenza B isolates in this study belong to the Victoria lineage. Five out of six isolates belong to clade 1A3-DEL, which relate closely to B/Washington/02/2009, with one isolate lacking the three amino acid deletion on the HA segment at position K162, N163, and D164. In comparison to the B/Colorado/06/2017, which is the representative of influenza B Victoria lineage vaccine strain, these substitutions include G129D, G133R, K136E, and V180R for HA protein. Importantly, the susceptibility to oseltamivir of influenza B isolates, but not A/H1N1 and A/H3N2 isolates, were reduced as assessed by the phenotypic assay. This study demonstrates the importance of monitoring genetic variation in influenza viruses regarding how acquired mutations could be associated with an improved adaptability for efficient transmission.

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Clinical Investigations. Comparison of Directigen Flu A+B with Real Time PCR in the Diagnosis of Influenza / Сравнение Иммунохроматографического Метода (Directigen Flu A+B) И Теста RT-PCR При Инфекциях Гриппа

Folia Medica ◽

10.1515/folmed-2015-0027 ◽

2015 ◽

Vol 57 (2) ◽

pp. 104-110 ◽

Cited By ~ 4

Author(s):

Golubinka Bosevska ◽

Nikola Panovski ◽

Elizabeta Janceska ◽

Vladimir Mikik ◽

Irena Kondova Topuzovska ◽

...

Keyword(s):

Real Time ◽

Influenza A Virus ◽

Real Time Pcr ◽

Influenza A ◽

Age Groups ◽

Influenza Viruses ◽

Influenza B Virus ◽

Influenza B ◽

B Virus ◽

Nose And Throat

AbstractEarly diagnosis and treatment of patients with influenza is the reason why physicians need rapid high-sensitivity influenza diagnostic tests that require no complex lab equipment and can be performed and interpreted within 15 min. The Aim of this study was to compare the rapid Directigen Flu A+B test with real time PCR for detection of influenza viruses in the Republic of Macedonia. MATERIALS AND METHODS: One-hundred-eight respiratory samples (combined nose and throat swabs) were routinely collected for detection of influenza virus during influenza seasons. Forty-one patients were pediatric cases and 59 were adult. Their mean age was 23 years. The patients were allocated into 6 age groups: 0 - 4 yrs, 5 - 9 yrs, 10 - 14 yrs, 15 - 19 yrs, 20-64 yrs and > 65 yrs. Each sample was tested with Directigen Flu A+B and CDC real time PCR kit for detection and typisation/subtypisation of influenza according to the lab diagnostic protocol. RESULTS: Directigen Flu A+B identified influenza A virus in 20 (18.5%) samples and influenza B virus in two 2 (1.9%) samples. The high specificity (100%) and PPV of Directigen Flu A+B we found in our study shows that the positive results do not need to be confirmed. The overall sensitivity of Directigen Flu A+B is 35.1% for influenza A virus and 33.0% for influenza B virus. The sensitivity for influenza A is higher among children hospitalized (45.0%) and outpatients (40.0%) versus adults. CONCLUSION: Directigen Flu A+B has relatively low sensitivity for detection of influenza viruses in combined nose and throat swabs. Negative results must be confirmed.

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Haemagglutination-inhibition antibodies against influenza A and influenza B in maternal and neonatal sera

Journal of Hygiene ◽

10.1017/s0022172400053353 ◽

1978 ◽

Vol 80 (1) ◽

pp. 13-19 ◽

Cited By ~ 6

Author(s):

N. Masurel ◽

J. I. de Bruijne ◽

H. A. Beuningh ◽

H. J. A. Schouten

Keyword(s):

Influenza Virus ◽

Maternal Age ◽

Influenza A ◽

Haemagglutination Inhibition ◽

Influenza Viruses ◽

Influenza B Virus ◽

Influenza B ◽

B Virus ◽

Duration Of Pregnancy ◽

Pregnancy And Birth

SUMMARYHaemagglutination inhibition (HI) antibodies against the influenza viruses A/Hong Kong/8/68 (H3N2) and B/Nederland/77/66 were determined in 420 paired sera from mothers and newborns (umbilical cord sera), sampled in 1970–1.A higher concentration of antibodies against influenza A virus was found more frequently in neonatal than in maternal sera. By contrast, low titres against influenza B virus were more frequently observed in neonatal than in maternal sera. Maternal age, duration of pregnancy, and birth-weight did not affect the results of the tests.It is suggested that the titre of the newborn against an epidemic influenza virus can be predicted from that of the mother. Furthermore, the maternal titre may be an indication of the susceptibility of the newborn infant to influenza infections.

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Influenza A and B viruses in the population of Vojvodina, Serbia

Archives of Biological Sciences ◽

10.2298/abs1401043r ◽

2014 ◽

Vol 66 (1) ◽

pp. 43-50 ◽

Cited By ~ 2

Author(s):

J. Radovanov ◽

V. Milosevic ◽

I. Hrnjakovic ◽

V. Petrovic ◽

M. Ristic ◽

...

Keyword(s):

Influenza A ◽

Respiratory Infections ◽

Influenza Viruses ◽

Influenza B Virus ◽

Nasopharyngeal Swab ◽

Influenza B ◽

Influenza A Viruses ◽

B Virus ◽

Life Threatening ◽

Seasonal Epidemic

At present, two influenza A viruses, H1N1pdm09 and H3N2, along with influenza B virus co-circulate in the human population, causing endemic and seasonal epidemic acute febrile respiratory infections, sometimes with life-threatening complications. Detection of influenza viruses in nasopharyngeal swab samples was done by real-time RT-PCR. There were 60.2% (53/88) positive samples in 2010/11, 63.4% (52/82) in 2011/12, and 49.9% (184/369) in 2012/13. Among the positive patients, influenza A viruses were predominant during the first two seasons, while influenza B type was more active during 2012/13. Subtyping of influenza A positive samples revealed the presence of A (H1N1)pdm09 in 2010/11, A (H3N2) in 2011/12, while in 2012/13, both subtypes were detected. The highest seroprevalence against influenza A was in the age-group 30-64, and against influenza B in adults aged 30-64 and >65.

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Non-Uniform and Non-Random Binding of Nucleoprotein to Influenza A and B Viral RNA

Viruses ◽

10.3390/v10100522 ◽

2018 ◽

Vol 10 (10) ◽

pp. 522 ◽

Cited By ~ 10

Author(s):

Valerie Le Sage ◽

Adalena Nanni ◽

Amar Bhagwat ◽

Dan Snyder ◽

Vaughn Cooper ◽

...

Keyword(s):

Influenza A ◽

Gene Segment ◽

Influenza Viruses ◽

Viral Rna ◽

Influenza B Virus ◽

Viral Gene ◽

Influenza B ◽

Influenza A Viruses ◽

Binding Profile ◽

Random Manner

The genomes of influenza A and B viruses have eight, single-stranded RNA segments that exist in the form of a viral ribonucleoprotein complex in association with nucleoprotein (NP) and an RNA-dependent RNA polymerase complex. We previously used high-throughput RNA sequencing coupled with crosslinking immunoprecipitation (HITS-CLIP) to examine where NP binds to the viral RNA (vRNA) and demonstrated for two H1N1 strains that NP binds vRNA in a non-uniform, non-random manner. In this study, we expand on those initial observations and describe the NP-vRNA binding profile for a seasonal H3N2 and influenza B virus. We show that, similar to H1N1 strains, NP binds vRNA in a non-uniform and non-random manner. Each viral gene segment has a unique NP binding profile with areas that are enriched for NP association as well as free of NP-binding. Interestingly, NP-vRNA binding profiles have some conservation between influenza A viruses, H1N1 and H3N2, but no correlation was observed between influenza A and B viruses. Our study demonstrates the conserved nature of non-uniform NP binding within influenza viruses. Mapping of the NP-bound vRNA segments provides information on the flexible NP regions that may be involved in facilitating assembly.

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Detection of severe acute respiratory syndrome coronavirus 2 and influenza viruses based on CRISPR-Cas12a

Experimental Biology and Medicine ◽

10.1177/1535370220963793 ◽

2020 ◽

pp. 153537022096379

Author(s):

Oraphan Mayuramart ◽

Pattaraporn Nimsamer ◽

Somruthai Rattanaburi ◽

Naphat Chantaravisoot ◽

Kritsada Khongnomnan ◽

...

Keyword(s):

Influenza Virus ◽

Severe Acute Respiratory Syndrome ◽

Influenza A ◽

Limit Of Detection ◽

Cross Reactivity ◽

Influenza Viruses ◽

Influenza B Virus ◽

Influenza B ◽

Influenza Virus A ◽

B Virus

Due to the common symptoms of COVID-19, patients are similar to influenza-like illness. Therefore, the detection method would be crucial to discriminate between SARS-CoV-2 and influenza virus-infected patients. In this study, CRISPR-Cas12a-based detection was applied for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus, and influenza B virus which would be a practical and attractive application for screening of patients with COVID-19 and influenza in areas with limited resources. The limit of detection for SARS-CoV-2, influenza A, and influenza B detection was 10, 103, and 103 copies/reaction, respectively. Moreover, the assays yielded no cross-reactivity against other respiratory viruses. The results revealed that the detection of influenza virus and SARS-CoV-2 by using RT-RPA and CRISPR-Cas12a technology reaches 96.23% sensitivity and 100% specificity for SARS-CoV-2 detection. The sensitivity for influenza virus A and B detections was 85.07% and 94.87%, respectively. In addition, the specificity for influenza virus A and B detections was approximately 96%. In conclusion, the RT-RPA with CRISPR-Cas12a assay was an effective method for the screening of influenza viruses and SARS-CoV-2 which could be applied to detect other infectious diseases in the future.

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