Integrated analysis of human influenza A(H1N1)virus infectionrelated genes to construct a suitable diagnostic model

The genome characteristics and structural functions of coding proteins correlate with the genetic diversity of the H1N1 virus,which aids in the understanding of its underlying pathogenic mechanism.In this study,analyses of the characteristic of the H1N1 virus infection-related genes,their biological functions,and infection-related reversal drugs were performed.Additionally,we used multi-dimensional bioinformatics analysis to identify the key genes and then used these to construct a diagnostic model for the H1N1 virus infection.There was a total of 169 differently expressed genes in the samples between 21 h before infection and 77 h after infection.They were used during the protein-protein interaction(PPI)analysis,and we obtained a total of 1725 interacting genes.Then,we performed a weighted gene co-expression network analysis(WGCNA)on these genes,and we identified three modules that showed significant potential for the diagnosis of the H1N1 virus infection.These modules contained 60 genes,and they were used to construct this diagnostic model,which showed an effective prediction value.Besides,these 60 genes were involved in the biological functions of this infectious virus,like the cellular response to type I interferon and in the negative regulation of the viral life cycle.However,20 genes showed an upregulated expression as the infection progressed.Other 36 upregulated genes were used to examine the relationship between genes,human influenza A virus,and infection-related reversal drugs.This study revealed numerous important reversal drug molecules on the H1N1 virus.They included rimantadine,interferons,and shikimic acid.Our study provided a novel method to analyze the characteristic of different genes and explore their corresponding biological function during the infection caused by the H1N1 virus.This diagnostic model,which comprises 60 genes,shows that a significant predictive value can be the potential biomarker for the diagnosis of the H1N1 virus infection.

Novel H1N1 influenza A virus infection in a patient with acute rejection after liver transplantation

BACKGROUND:The 2009 H1N1 influenza A virus was first identified in April 2009 and rapidly evolved into a pandemic. Recipients of solid-organ transplants have a higher risk for severe infection because of immunosuppression.There are limited reports of 2009 H1N1 influenza in liver transplant recipients,especially in China. METHODS:We present a case of a 48-year-old male liver transplant recipient with 2009 H1N1 influenza A virus.He received therapy for acute rejection after transplantation and was confirmed with H1N1 virus infection. RESULTS:The patient was started on oseltamivir(75 mg, orally twice daily)and had a benign hospital course,with defervescence and resolution of symptoms within 72 hours. The follow-up chest radiograph after discharge was normal. CONCLUSIONS:The 2009 H1N1 influenza in this hospitalized transplant recipient was relatively mild,and prolonged viral shedding was not noted.Oseltamivir can be a valid measure in immunocompromised individuals.

Clinical Characteristics of H1N1 Influenza A-Associated Mild Encephalopathy with Reversible Splenial Lesion: 4 Pediatric Cases

Objective Mild encephalopathy with reversible splenial lesion(MERS)is associated with a variety of infections and anti-epileptic drug withdrawal.Here we report the clinical characteristics of H1N1 influenza A-associated MERS based on our experience of four pediatric cases.Methods A detailed retrospective analysis of four patients with H1N1 influenza A-associated MERS was performed at Guangzhou Women and Children’s Medical Center.Results All patients exhibited mild influenza-like illness and seizures.Three patients presented with a new-onset seizure with fever after 5 years of age.75%patients had altered mental status.For all four patients,influenza A(H1N1)viral RNA was detected in throat swab specimens at least twice.Brain magnetic resonance images revealed similar ovoid lesions in the corpus callosum,mainly in the splenium and for one patient in the splenium and genu of the corpus callosum.Only one patient had an abnormal electroencephalogram tracing.Cells and protein in the cerebrospinal fluid were normal in all patients.All patients received oseltamivir and one patient received intravenous immunoglobulin.As a result,all patients fully recovered after 2 months and showed no neurologic sequelae at discharge.Conclusion This case series provides insight towards clinical features of H1N1 influenza A-associated MERS.

Knowledge and preventive measures practiced by junior high school students from Mexico City regarding influenza A (H1N1)

Background: Influenza A (H1N1) is the most recent pandemic disease that has affected the human population. Objective: To evaluate knowledge and preventive measures related with this disease one year after the epidemic of Mexico- that took place in 2009. Material and methods: An epidemiologic survey regarding influenza A (H1N1) was conducted in June 2010 among 2541 students from the second grade of all public high schools in a borough in Mexico City. The questionnaire included items on the knowledge of the disease and practice of preventive measures. Results: Most students obtained the information from television, half of them from parents and only one fifth from teachers;72% of the participants had a favorable knowledge about the disease and the measures to avoid being infected. However, only 37% practiced such preventive measures. Conclusion: Knowledge has a positive influence on practices towards health. Parents and teachers have an important role in health education, thus efforts should be directed to involve them more intensely in health education.

In silico modification of oseltamivir as neuraminidase inhibitor of influenza A virus subtype H1N1

This research focused on the modification of the functional groups of oseltamivir as neuraminidase inhibitor against influenza A virus subtype H1N1.Interactions of three of the best ligands were evaluated in the hydrated state using molecular dynamics simulation at two different temperatures.The docking result showed that AD3BF2 D ligand（N-[（1S,6R）-5-amino-5-{[（2R,3S,4S）-3,4-dihydroxy-4-（hydroxymethyl） tetrahydrofuran-2-yl]oxy}-4-formylcyclohex-3-en-1-yl]acetamide-3-（1-ethylpropoxy）-1-cyclohexene-1-carboxylate） had better binding energy values than standard oseltamivir.AD3BF2 D had several interactions,including hydrogen bonds,with the residues in the catalytic site of neuraminidase as identified by molecular dynamics simulation.The results showed that AD3BF2 D ligand can be used as a good candidate for neuraminidase inhibitor to cope with influenza A virus subtype H1N1.

Effect of Aluminum Hydroxide Adjuvant on the Immunogenicity of the 2009 Pandemic Influenza A/H1N1 Vaccine:Multi-level Modeling of Data with Repeated Measures

Objective To evaluate the effect of the aluminum hydroxide （Al-OH） adjuvant on the 2009 pandemic influenza A/H1N1 （pH1N1） vaccine. Methods In a multicenter, double-blind, randomized, placebo-controlled trial, participants received two doses of split-virion formulation containing 15 ug hemagglutinin antigen, with or without aluminum hydroxide （N-OH）. We classified the participants into six age categories （〉61 years, 41-60 years, 19-40 years, 13-18 years, 8-12 years, and 3-7 years） and obtained four blood samples from each participant on days 0, 21, 35, and 42 following the first dose of immunization. We assessed vaccine immunogenicity by measuring the geometric mean titer （GMT） of hemagglutination inhibiting antibody. We used a two-level model to evaluate the fixed effect of aluminum Al-OH and other factors, accounting for repeated measures. Results The predictions of repeated measurement on GMTs of formulations with or without Al-OH, were 80.35 and 112.72, respectively. Al-OH significantly reduced immunogenicity after controlling for time post immunization, age-group and gender. Conclusion The Al-OH adjuvant does not increase but actually reduces the immunogenicity of the split-virion pH1N1 vaccine.

Morphofunctional Characteristics of Pulmonary Surfactant System and Its Effect on Immune Cells in Influenza A (H1N1) Pathogenesis

There is an annual increase of influenza-related SARI cases in winter months. Despite the high relevance of this problem, influenza pathogenesis and the role of surfactant system and its SP-A (surfactant protein A) enzyme in antiviral defense remain poorly understood. SP-A activates macrophage M1 polarization and triggers an antiviral response due to the activation of T-cells and dendritic cells. Therefore, surfactant system is an important element of infection protection and a promising therapeutic target.

Seroprevalence study of infection with influenza A(H1N1)pdm09 virus in San Felipe Town, Chile

Objective: To know the natural history of the first wave of pandemic influenza A(H1N1)pdm09 in the Southern hemisphere, through the detection of antibodies against influenza A(H1N1)pdm09 in a selected community, to estimate the population attack rate and its variations, the consultation rates, hospitallization and mortality rates. Methodology: A representative random sample of the population of a commune in Chile (San Felipe) was interviewed and taken blood samples between January and March 2010. A study against the antibodies of the influenza A(H1N1) pdm09 virus was conducted, by the technique of the Hemaglutination Inhibition (HAI) according to standardized methodology. Subjects with antibody titers ≥1:40 were considered positive. Results: 13.5% of the population of San Felipe had antibodies against influenza A(H1N1)pdm09;this percentage reached 30% of the population between 0 and 18 years and 6.1% among those over 19 years. The age variable was the only factor that evidenced significant differences in the prevalence of antibodies. There were no significant differences related to gender, vaccination history against seasonal inluenza, or comorbidity. 51% of people with positive serology showed IN-FLUENZA-LIKE SYMPTOMS. Conclusions: A relevant percentage of subclinical disease was detected in the first pandemic wave in Chile and the proportion of people with SARI and deaths was small. Data from epidemiological surveillance were useful to estimate the trend of TSI but not its magnitude.

Molecular Characterization of Avian-like H1N1 Swine Influenza A Viruses Isolated in Eastern China, 2011

Currently, three predominant subtypes of influenza virus are prevalent in pig populations worldwide： H1N1, H3N2, and H1N2. European avian-Hke H1N1 viruses, which were initially detected in European pig populations in 1979, have been circulating in pigs in eastern China since 2007. In this study, six influenza A viruses were isolated from 60 swine lung samples collected from January to April 2011 in eastern China. Based on whole genome sequencing, molecular characteristics of two isolates were determined. Phylogenetic analysis showed the eight genes of the two isolates were closely related to those of the avian-like H1N1 viruses circulating in pig populations, especially similar to those found in China. Four potential glycosylation sites were observed at positions 13, 26, 198, 277 in the HA1 proteins of the two isolates. Due to the presence of a stop codon at codon 12, the isolates contained truncated PB1-F2 proteins. In this study, the isolates contained 591Q, 627E and 701N in the polymerase subunit PB2, which had been shown to be determinants of virulence and host adaptation. The isolates also had a D rather than E at position 92 of the NS1, a marker of mammalian adaptation. Both isolates contained the GPKV motif at the PDZ ligand domain of the 3＇ end of the NS1, a characteristic marker of the European avian-like swine viruses since about 1999, which is distinct from those of avian, human and classical swine viruses. The M2 proteins of the isolates have the mutation （S31N）, a characteristic marker of the European avian-like swine viruses since about 1987, which may confer resistance to amantadine and rimantadine antivirals. Our findings further emphasize the importance of surveillance on the genetic diversity of influenza A viruses in pigs, and raise more concerns about the occurrence of cross-species transmission events.

The interaction between the 2009 H1N1 influenza A hemagglutinin and neuraminidase: mutations, co-mutations, and the NA stalk motifs

As the world is closely watching the current 2009 H1N1 pandemic unfold, there is a great interest and need in understanding its origin, genetic structures, virulence, and pathogenicity. The two surface proteins, hemagglutinin (HA) and neuraminidase (NA), of the influenza virus have been the focus of most flu research due to their crucial biological functions. In our previous study on 2009 H1N1, three aspects of NA were investigated: the mutations and co-mutations, the stalk motifs, and the phylogenetic analysis. In this study, we turned our attention to HA and the interaction between HA and NA. The 118 mutations of 2009 H1N1 HA were found and mapped to the 3D homology model of H1, and the mutations on the five epitope regions on H1 were identified. This information is essential for developing new drugs and vaccine. The distinct response patterns of HA to the changes of NA stalk motifs were discovered, illustrating the functional dependence between HA and NA. With help from our previous results, two co-mutation networks were uncovered, one in HA and one in NA, where each mutation in one network co-mutates with the mutations in the other network across the two proteins HA and NA. These two networks residing in HA and NA separately may provide a functional linkage between the mutations that can impact the drug binding sites in NA and those that can affect the host immune response or vaccine efficacy in HA. Our findings demonstrated the value of conducting timely analysis on the 2009 H1N1 virus and of the integrated approach to studying both surface proteins HA and NA together to reveal their interdependence, which could not be accomplished by studying them individually.

Structure and Anti-influenza A(H1N1) Virus Activity of Three Polysaccharides from Eucheuma denticulatum

Three polysaccharides （EW, EH and EA） were prepared from a red alga Eucheuma denticulatum by sequential extraction with cold water, hot water and sodium hydroxide water solution. Their monosaccharide compositions, relative molecular mass and structural characterization were determined by gas chromatography, high performance liquid chromatography, fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy methods. EW was hybrid l/k/v-carrageenan （701/17k/13v-car- rabiose）, EH was mainly t-carrageenan, and EA was mainly α-1,4-Glucan （88%） but mixed with small amount of t-carrageenan （12%）. The relative molecular mass ofEW, EH and EA was 480, 580 and 510kDa, respectively. The anti-influenza A （H1N1） virus activity of these three polysaccharides was evaluated using the Madin-Darby canine kidney cells model. EW showed good anti-H1N1 virus activity, its ICso was 276.5 μg mL-1, and the inhibition rate to H1N1 virus was 52% when its concentration was 250 μgmL-1. The ICs0 of t-carrageenan EH was 366.4 μgmL1, whereas EA showed lower anti-H1N1 virus activity （IC50〉430μgmL-1）. Available data obtained give positive evidence that the hybrid carrageenan EW from Eueheuma denticulatum can be used as potential anti-H1N1 virus inhibitor in future.

Genetic Characteristics of 2009 Pandemic H1N1 Influenza A Viruses Isolated from China's Mainland

A total of 100 H1N1 flu real-time-PCR positive throat swabs collected from fever patients in Zhejiang, Hubei and Guangdong between June and November 2009, were provided by local CDC laboratories. After MDCK cell culture, 57 Influenza A Pandemic （H1N1） viruses were isolated and submitted for whole genome sequencing. A total of 39 HA sequences, 52 NA sequences, 36 PB2 sequences, 31 PB1 sequences, 40 PA sequences, 48 NP sequences, 51 MP sequences and 36 NS sequences were obtained, including 20 whole genome sequences. Sequence comparison revealed they shared a high degree of homology （96%-99%） with known epidemic strains （A/Califomia/04/2009（H1N1）. Phylogenetic analysis showed that although the sequences were highly conserved, they clustered into a small number of groups with only a few distinct strains. Site analysis revealed three substitutions at loop 220 （221-228） of the HA receptor binding site in the 39 HA sequences： A/Hubei/86/2009 PKVRDQEG→PKVRDQEA, A/Zhejiang/08/2009 PKVRDQEG→PKVRDQER, A/Hubei/75/2009 PKVRDQEG→PKVRDQGG, the A/Hubei/75/2009 was isolated from an acute case, while the other two were from patients with mild symptoms. Other key sites such as 119, 274, 292 and 294 amino acids of NA protein,627 of PB2 protein were conserved. Meanwhile, all the M2 protein sequences possessed the Ser32Asn mutation, suggesting that these viruses were resistant to adamantanes. Comparison of these sequences with other H1N1 viruses collected from the NCBI database provides insight into H1N1 transmission and circulation patterns.

Clinical Analysis of Influenza A (H1N1) Viral Pneumonia Complicated with Bacterial Infection

Purpose: We investigated the efficacy of potent or combined antibiotics in patients suffering bacterial infections secondary to H1N1 by retrospectively analyzing their bacterial pathogen spectrum and clinical characteristics. Methods: Multi-center retrospective analysis was performed using clinical data of H1N1 patients from 27 hospitals in Hebei Province, China, from November 1 to December 31, 2009. Results: Of 480 H1N1-infected patients enrolled from an inpatient clinic, 91 were positive for bacterial culture. Bacteria were detected in sputum culture at 7.00 ± 8.87 days post-admission. Compared with the negative group, the patients in the positive sputum culture group had a higher mean age and prevalence of basic diseases, higher APECHEII (Acute Physiology and Chronic Health Evaluation II) score within 24 hours of admission, longer hospital stays, and higher mortality. In total, 189 bacterial strains were isolated, with the majority of samples testing positive for Acinetobacter baumanii (47), Streptococcus viridians (26), or Pseudomonas aeruginosa (19). S. viridians was the major cause of infection within 3 days of admission, while A. baumanii infection was more prevalent from 4 days post-admission;there was a significant difference in the constituent ratio between the two pathogens (p 0.001). Compared with patients administered common antibiotics, the potent antibiotics group showed no significant difference in hospitalization time, time until bacterial detection, mortality, or detection ratio of resistant strains (p > 0.05). Conclusions: Complicated bacterial infection in H1N1 patients increases hospitalization time and mortality. Gram-negative bacilli and multi-resistant strains are the main sources of infection. Early administration of potent or combined antibiotics, even during the period of rapid onset, may not be suitable in H1N1-infected patients, particularly previously healthy young patients.

Severe Novel Influenza A(H1N1) in Shanghai:Clinical Features, Therapeutic Management and Risk Factors for Mortality

Objective To analyze the clinical features,therapeutic management and risk factors for mortality of patients with severe novel A(H1N1)influenza in Shanghai,China.Methods All patients were diagnosed by influenza A(H1N1)virus mRNA detection.Chest CT scan,routine blood,hepatic function,humoral and cellular immunity,sputum smears,and sputum cultures were performed.Logistic analysis was applied to identify risk factors for mortality.Results Total of 68 patients were enrolled in this study,the primary clinical symptoms including cough(66,97.1%),expectoration(41,60.3%),and polypnea(41,60.3%).Altogether,37(54.4%)and 11(16.2%)patients were infected with bacterial and fungal,respectively.CT scan demonstrated that 67(98.6%)patients had pneumonia.Oxygen therapy,oseltamivir,antibiotic and antifungal drugs were performed in 68(100%),66(97.1%),39(57.4%),and 11(16.2%)patients,respectively.Finally,4 of 68 patients died.Logistic analysis demonstrated that there was a significant correlation between the percentage of neutrophils and mortality before therapy and direct bilirubin content and mortality after therapy,respectively.Conclusions Patients with severe H1N1 influenza were susceptible to bacterial and/or fungal infection.The risk factors for mortality may be associated with pre-therapeutic neutrophil percentage and post-therapeutic direct bilirubin content.

Factors Associated with Death Due to 2009 Influenza A (H1N1) Virus Infection and Acute Respiratory Distress Syndrome in Beijing, 2009-2011

Objective Patients with H1N1 virus infection were hospitalized and quarantined, and some of them developed into acute respiratory failure, and were transfered to the medical intensive care unit of Beijing Ditan Hospital, Capital Medical University in Beijing, China. Methods The clinical features and preliminary epidemiologic findings among 30 patients with confirmed H1N1 virus infection who developed into acute respiratory failure for ventilatory support were investigated. Results A total of 30 patients(37.43 ± 18.80 years old) with 2009 influenza A(H1N1) related acute respiratory distress syndrome(ARDS) received treatment with mechanical ventilation, 15 cases of whom were male and 17 cases died of ARDS. Fatal cases were significantly associated with an APACHE Ⅱ score(P = 0.016), but not with PaO 2 /FIO 2(P = 0.912) and chest radiograph(P = 0.333). The most common complication was acute renal failure(n = 9). Five patients received extracorporeal membrane oxygenation(ECMO), 3 of whom died and the others survived. The major causes of death were multiple organ dysfunction syndrome(MODS)(39%), intractable respiratory failure(27%) and sepsis(20%). Conclusions Most patients with respiratory failure due to influenza A(H1N1) virus infection were young, with a high mortality, particularly associated with APACHE Ⅱ score, secondary infection of lung or type 2 diabetes mellitus.

Identification of the child with influenza A (H1N1): Clinical criteria versus the rapid influenza A-B test

Introduction: During the influenza A (H1N1) pandemic infection, the Ministry of Health in Mexico recommended that it be considered as a suggestive clinical picture in patients with fever, cough and headache. In some places where the resource was available, the rapid seasonal influenza (A-B) test was used as an alternative identification strategy. Methods: From April 2009 to May 2010, patients under 18 years of age with acute respiratory tract symptoms were included in a retrospective study. They underwent the following procedures: 1) application of the clinical criteria recommended by the federal Ministry of Health during the A (H1N1) pandemic;2) rapid test for seasonal influenza (A-B), and 3) search for the influenza A (H1N1) virus by means of the real time polymerase chain reaction (RT-PCR). The study was approved by the research and ethics committee at the Central South Hospital of the government-owned Mexican Petroleum Company (PEMEX). Results: One hundred and thirty pediatric patients with a median age of eight years and a range between one and 17 years were included. Taking into account the Ministry of Health’s criteria, we found the following: 50% sensitivity, 69% specificity, 80% positive predictive value and 27% negative predictive value versus the rapid test that displayed 82% sensitivity, 70% specificity, 80% positive predictive value and 27% negative predictive value. Conclusions: Clinical criteria display low sensitivity in the infected children studied, whereas the rapid influenza A-B test constitutes a better option to identify these patients.

Intergenic subset organization within a set of geographically-defined viral sequences from the 2009 H1N1 influenza A pandemic

We report a bioinformatic analysis of the datasets of sequences of all ten genes from the 2009 H1N1 influenza A pandemic in the state of Wisconsin. The gene with the greatest summed information entropy was found to be the hemagglutinin (HA) gene. Based upon the viral ID identifier of the HA gene sequence, the sequences of all of the genes were sorted into two subsets, depending upon whether the nucleotide occupying the position of maximum entropy, position 658 of the HA sequence, was either A or U. It was found that the information entropy (H) distributions of subsets differed significantly from each other, from H distributions of randomly generated subsets and from the H distributions of the complete datasets of each gene. Mutual information (MI) values facilitated identification of nine nucleotide positions, distributed over seven of the influenza genes, at which the nucleotide subsets were disjoint, or almost disjoint. Nucleotide frequencies at these nine positions were used to compute mutual information values that subsequently served as weighting factors for edges in a graph net-work. Seven of the nucleotide positions in the graph network are sites of synonymous mutations. Three of these sites of synonymous mutation are within a single gene, the M1 gene, which occupied the position of greatest graph centrality. It is proposed that these bioinformatic and network graph results may reflect alterations in M1-mediated viral packaging and exteriorization, known to be susceptible to synonymous mutations.

Novel host markers in the 2009 pandemic H1N1 influenza a virus

The winter of 2009 witnessed the concurrent spread of 2009 pandemic H1N1 with 2009 seasonal H1N1. It is clinically important to develop knowledge of the key features of these two different viruses that make them unique. A robust pattern recognition technique, Random Forests, was employed to uncover essential amino acid markers to differentiate the two viruses. Some of these markers were also part of the previously discovered genomic signature that separate avian or swine from human viruses. Much research to date in search of host markers in 2009 pandemic H1N1 has been primarily limited in the context of traditional markers of avian-human or swine-human host shifts. However, many of the molecular markers for adaptation to human hosts or to the emergence of a pandemic virus do not exist in 2009 pandemic H1N1, implying that other previously unrecognized molecular determinants are accountable for its capability to infect humans. The current study aimed to explore novel host markers in the proteins of 2009 pandemic H1N1 that were not present in those classical markers, thus providing fresh and unique insight into the adaptive genetic modifications that could lead to the generation of this new virus. Random Forests were used to find 18 such markers in HA, 15 in NA, 9 in PB2, 11 in PB1, 13 in PA, 10 in NS1, 1 in NS2, 11 in NP, 3 in M1, and 1 in M2. The amino acids at many of these novel sites in 2009 pandemic H1N1 were distinct from those in avian, human, and swine viruses that were identical at these positions, reflecting the uniqueness of these novel sites.

An Epidemiological Study on Influenza A(H1N1) in Makkah

The flu pandemic is a global outbreak of a new strain of influenza A virus subtype H1N1, termed Pandemic H1N1/09 virus by the World Health Organization (WHO), which was first identified in April 2009. The disease has also been termed novel Influenza A(H1N1) and 2009 H1N1 flu by the US Centers for Disease Control and Prevention (CDC), and is commonly known as swine flu. The main strain of the virus has been termed A/California/07/2009 (H1N1) by scientists. This study was conducted to describe the epidemiology of influenza A(H1N1) infections in KSA during 2009. A descriptive study was carried out among attendants at hospitals and primary health care centers in Makkah during 2009, irrespective of age and sex. The data were collected by interviewing suspected persons using a pre-designed questionnaire, clinical examination, and specific laboratory investigation. A total of 1138 subjects were included in the study. Among the study population, 25% of the cases between 15 and 24 years old were found positive for influenza A(H1N1) by PCR technique. Although a significant population was affected by influenza A(H1N1) during 2009 in Makkah, the efforts and steps taken by health authorities at all levels―especially those in Directorate of Health Affairs of Makkah—helped to avert the mortality associated with the H1N1 influenza among the residents and those coming for Umrah and Hajj to Makkah by providing and timely diagnosis.

Successful High-Dosage Dexamethasone Treatment of H1N1 Influenza A Pneumonia Complicated with Acute Necrotizing Encephalitis in an HIV-Infected Adult

Neurological manifestations in H1N1 influenza A infection are very rare, especially in adults, and its mechanism of action is still uncertain. Here, we reported the case of a 53-year-old woman with human immunodeficiency virus infection (HIV) who had H1N1 influenza A pneumonia complicated with very rare acute necrotizing encephalitis, although the HIV was under control. With prompt identification and administration of high dosage of dexamethasone, her mental status improved from stupor to clear, with minimal right hemiparesis. Further, brain magnetic resonance image revealed great resolution of mass effect. This dramatic improvement in response to the treatment may improve our understanding of the pathophysiology between H1N1 influenza A infection and acute necrotizing encephalitis.