Rapid detection for primary screening of influenza A virus: microfluidic RT-PCR chip and electrochemical DNA sensor

Introduction: The influenza A virus is responsible for high morbidity and mortality in children and adults worldwide. Thus, a rapid, sensitive, and specific diagnosis tool is required. Methodology: An immunofluorescence assay (DFA) and a lateral-flow immunochromatographic assay were compared with RT-PCR for detection of the influenza A virus in 113 nasopharyngeal wash samples obtained from pediatric patients. Samples were collected between July and December 2009, during the pandemic outbreak of influenza A H1N1/09. Results: The sensitivity, specificity, and positive and negative predictive values obtained for the DFA were 68.97%, 76.63%, 75.47%, and 70%, respectively, while the values obtained for the immunochromatographic assay were 58.62%, 81.82%, 77.27%, and 65.22%, respectively. The frequency of the influenza A virus was 51.33%, and a total of 27 samples were positive for the pandemic influenza A H1N1/09. Conclusions: DFA and the immunochromatographic assay can be important tools for patient care during influenza season and in outbreaks as they usually provide results within 45 minutes. Furthermore, positive results in conjunction with the patient’s symptoms could provide a correct diagnosis, thus facilitating appropriate patient management. Nonetheless, the results of these assays still require confirmation by RT-PCR.

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Shedding and transmission of a live attenuated influenza A virus vaccine in pre-weaned pigs under field conditions

PLoS ONE ◽

10.1371/journal.pone.0246690 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0246690

Author(s):

Gustavo Lopez Moreno ◽

Jayaveeramuthu Nirmala ◽

Christa Goodell ◽

Marie Culhane ◽

Montserrat Torremorell

Keyword(s):

Influenza A Virus ◽

Influenza A ◽

Rt Pcr ◽

Pcr Assay ◽

Post Vaccination ◽

Nasal Swabs ◽

Common Strategy ◽

Low Levels ◽

Live Attenuated Influenza Virus ◽

Pig Health

Influenza A virus (IAV) is one of the most important respiratory viruses affecting pig health and vaccination is the most common strategy to control influenza infections. In this field study we assessed the onset and duration of shedding of a live attenuated influenza virus (LAIV) vaccine, its ability to transmit to non-vaccinated pigs and whether the LAIV could be aerosolized and detected in the environment. Thirty-three litters (n = 33) of a farm using the LAIV vaccine were selected for the study, a subset of them (n = 12) were left unvaccinated and a subset of piglets (n = 3) in vaccinated litters were also left unvaccinated to serve as sentinels. Selected piglets from the litters were sampled multiple days post vaccination (DPV) by collecting nasal swabs and blood, and were tested using a LAIV vaccine specific RT-PCR assay and hemagglutination inhibition assay against the LAIV strains respectively. Environmental specimens consisting of air and surface wipes were also collected. One hundred percent (21/21) of the vaccinated litters tested LAIV positive 1 DPV and until 6 DPV. In contrast, only five (5/33) of the thirty-three non-vaccinated pigs tested positive during the course of the study. Viable LAIV was confirmed in vaccinated pigs by cell culture and whole genome sequencing. In addition, low levels of LAIV RNA (RT-PCR Ct values ranging between 33 and 38) were detected in all air specimens collected on the day of vaccination and until 6 DPV (3/10). Pigs had maternally derived antibodies reactive against the LAIV strains which may have influenced the degree of shedding observed. Under the conditions of this study, shedding of the LAIV from vaccinated pigs was limited in time, resulted in minimal transmission to non-vaccinated pigs and was detected in low levels in aerosols collected in the vaccinated rooms likely influenced by the presence of maternally derived antibodies against the LAIV strains.

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