Laboratory diagnosis of influenza: recent advances

Primer development to obtain complete coding sequence of HA and NA genes of influenza A/H3N2 virus

Background

Influenza is an acute respiratory illness and has become a serious public health problem worldwide. The need to study the HA and NA genes in influenza A virus is essential since these genes frequently undergo mutations. This study describes the development of primer sets for RT-PCR to obtain complete coding sequence of Hemagglutinin (HA) and Neuraminidase (NA) genes of influenza A/H3N2 virus from Indonesia. The primers were developed based on influenza A/H3N2 sequence worldwide from Global Initiative on Sharing All Influenza Data (GISAID) and further tested using Indonesian influenza A/H3N2 archived samples of influenza-like illness (ILI) surveillance from 2008 to 2009.

Results

An optimum RT-PCR condition was acquired for all HA and NA fragments designed to cover complete coding sequence of HA and NA genes. A total of 71 samples were successfully sequenced for complete coding sequence both of HA and NA genes out of 145 samples of influenza A/H3N2 tested.

Conclusions

The developed primer sets were suitable for obtaining complete coding sequences of HA and NA genes of Indonesian samples from 2008 to 2009.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-016-2235-8) contains supplementary material, which is available to authorized users.

Performance characteristics of a rapid immunochromatographic assay for detection of influenza virus in children during the 2003 to 2004 influenza season

STUDY OBJECTIVE

We evaluate the performance of a rapid assay (Binax NOW) for the detection of influenza A virus in children.

METHODS

The performance of an in vitro rapid immunochromatographic assay for detection of influenza A virus was compared to viral culture in 4,383 consecutive respiratory specimens received during the 2003 to 2004 season, which included an influenza A epidemic in October and November of 2003.

RESULTS

The overall test sensitivity was 61.6% (95% confidence interval [CI] 60.3% to 63.2%) and specificity was 95.8% (95% CI 95.1% to 96.3%). In preplanned subset analyses, we found the test more sensitive in infants aged 90 days or younger (sensitivity 70.3%; specificity 96.6%) and less specific during the epidemic (sensitivity 61.7%; specificity 90.4%).

CONCLUSION

This rapid assay was highly specific for detecting influenza A in children and thus appears useful for confirming this infection. Because of its limited sensitivity, however, a negative test cannot rule out influenza A.

Influenza burden of illness, diagnosis, treatment, and prevention: what is the evidence in children and where are the gaps?

Influenza is a disease of global public health significance. Traditionally the emphasis has been on adult disease because of the impact of influenza related mortality in the elderly and other high risk groups. However, it is becoming increasingly better recognised that young children suffer considerable morbidity from influenza. There are also potential consequences for siblings, parents, other carers, and extended family members in terms of secondary infections and carer leave. Influenza infection in childhood could be effectively prevented through vaccination. However, the United States is the only industrialised country currently recommending universal influenza vaccination for young children (between the ages of 6 and 23 months), as opposed to vaccinating only those with high risk conditions.

Comparison of a new lateral-flow chromatographic membrane immunoassay to viral culture for rapid detection and differentiation of influenza A and B viruses in respiratory specimens

The performance of a new rapid lateral-flow chromatographic membrane immunoassay test kit for detection of influenza virus was evaluated and compared to that of viral culture in respiratory secretions collected from 400 adults and children seen at three large university hospitals during the recent 2003 influenza season. The rapid test provided results in 15 min, with excellent overall performance statistics (sensitivity, 94.4%; specificity, 100%; positive predictive value, 100%; negative predictive value, 97.5%). Both influenza A and B type viruses were reliably detected, with no significant difference in performance statistics noted by influenza virus type or by the center performing the test.

Comparison of the directigen flu A+B membrane enzyme immunoassay with viral culture for rapid detection of influenza A and B viruses in respiratory specimens

The performance of a commercially available, rapid membrane enzyme immunoassay for influenza A and B virus detection was compared to that of viral culture in 4,092 respiratory specimens collected from patients presenting with respiratory symptoms during the 2002-2003 influenza season. The test's overall sensitivity was 43.83%, lower than previously reported but similar for detection of both influenza A and B viruses (42.98 versus 44.76%). However, specificity, 99.74%, was excellent for both influenza A and B viruses (99.82 versus 99.92%). These values make this test a very good confirmatory test when clinical suspicion is high, but a less accurate screening test for large populations.

Influenza A community-acquired pneumonia in East London infants and young children

BACKGROUND

Community-acquired pneumonia (CAP) is common in young children, but there are few data in Europe on influenza A virus as a cause of childhood CAP. The aim of this study was to determine the relative contributions of different etiologic agents to CAP in children.

METHODS

This was a 6-month prospective study of pediatric accident and emergency and general practice consultations with a diagnosis of CAP. Nasopharyngeal aspirates for viral immunofluorescence and PCR studies and blood cultures for bacterial studies were taken from 51 children with symptoms, signs and chest radiographic features that satisfied a diagnosis of pneumonia.

RESULTS

An etiologic agent was isolated from 25 patients (49%). A viral cause was identified in 22 patients (43%), and influenza A virus and respiratory syncytial virus (RSV) were detected in 16 and 18% of all cases, respectively. Only four patients (8%) had a positive bacterial blood culture; three had Streptococcus pneumoniae and one had Neisseria meningitidis W135. Mycoplasma pneumoniae was detected in 2 children, and mixed infections were detected in 5 (10%). The use of viral PCR increased the detection rate of influenza A virus by 100%.

CONCLUSION

Influenza A virus caused more than one-third of all viral CAP cases, a rate comparable with that of RSV CAP. Viral PCR doubled the diagnostic yield of influenza A virus. The clinical burden of influenza A CAP was comparable with that of RSV CAP, as measured by the duration of fever, hospital stay and total duration of illness.

Comparison of lateral-flow immunoassay and enzyme immunoassay with viral culture for rapid detection of influenza virus in nasal wash specimens from children

The performance of two commercially available rapid test kits for influenza virus detection was compared to that of viral culture by using 356 nasal wash specimens collected during the 2001 to 2002 influenza season. Overall, the two rapid tests were easy to perform and showed comparable sensitivities (70.4 and 72.2%) and specificities (97.7 and 98.3%); for both test kit groups, most of the specimens that yielded false-negative results were found to be growing influenza B virus.