Advances in laboratory assays for detecting human metapneumovirus

Epidemiology and diagnosis technologies of human metapneumovirus in China: a mini review

Human metapneumovirus (HMPV) is a newly identified pathogen causing acute respiratory tract infections in young infants worldwide. Since the initial document of HMPV infection in China in 2003, Chinese scientists have made lots of efforts to prevent and control this disease, including developing diagnosis methods, vaccines and antiviral agents against HMPV, as well as conducting epidemiological investigations. However, effective vaccines or special antiviral agents against HMPV are currently not approved, thus developing early diagnosis methods and knowing its epidemiological characteristics will be beneficial for HMPV control. Here, we summarized current research focused on the epidemiological characteristics of HMPV in China and its available detection methods, which will be beneficial to increase the public awareness and disease control in the future.

Identification of γ-Fagarine as a novel antiviral agent against respiratory virus (hMPV) infection

Human metapneumovirus (hMPV) causes significant upper and lower respiratory disease in all age groups worldwide. However, there is no licensed drugs or vaccine available against hMPV. γ-Fagarine, an alkaloid isolated from the root of zanthoxylum, has been reported to be effective in the treatment of cancer, inflammatory diseases and antivirals. However, little is known about the inhibitory effect of γ-Fagarine against respiratory virus infection and the mechanism. In this study, we aim to investigate the effect of γ-Fagarine on hMPV infection and explore its underlying molecular mechanisms. Vero-E6 and 16HBE cells were used as cell models. Virus replication and microcosm character were explored in Vero-E6 cells. Then, the antiviral activities were investigated by quantitative real-time PCR (RT-qPCR), western blotting (WB), and indirect immunofluorescence assays (IFAs) in Vero-E6 and 16HBE. Potential mechanisms of γ-Fagarine related to HSPG and lysosome pH were assessed in 16HBE cells. Lastly, a virus-infected mouse model was established and antiviral assay in vivo was conducted. γ-Fagarine showed no toxicity toward Vero-E6 cells and 16HBE cells but demonstrated anti-hMPV activity. Virus titers of γ-Fagarine group were reduced to 33% and 45% of the hMPV groups, respectively. Besides, mechanistic studies revealed that γ-Fagarine could inhibit hMPV by dual mechanisms of direct restraining virus binding with HSPG and influencing lysosome pH. Furthermore, oral delivery of γ-Fagarine to hMPV-infected mice at a dosage of 25 mg/kg reduced the hMPV load in lung tissues. After γ-Fagarine treatment, pathological damage caused by viral infection was also ameliorated. These findings suggest that γ-Fagarine has antiviral effects in vitro and in vivo, which are associated with its ability to restrain virus binding with HSPG and influence lysosome pH, thus indicating that γ-Fagarine has the potential to serve as a candidate to fight against hMPV infection and other respiratory viruses such as influenza viruses and SARS-CoV-2.

Immunogenicity and protective efficacy of human metapneumovirus virus-like particles produced by a recombinant baculovirus in mice

BACKGROUND

Human metapneumovirus (HMPV) causes respiratory tract infections among infant, elderly, and immunocompromised patients, with significant mortality. Currently no licensed vaccines or therapeutic agents of HMPV exist.

METHODS

HMPV virus-like particle (VLP) was constructed by co-expressing fusion protein of HMPV and matrix 1 protein of influenza virus using the baculovirus expression. Mice were immunized with VLP with or without aluminum hydroxide (alum) adjuvant by intramuscular route respectively. Sera were determined for titers of IgG and neutralizing antibody. Splenic lymphocytes were determined by IFN-γ and IL-4 ELISPOT. Mice were challenged with HMPV, and protective efficacy was evaluated.

RESULTS

We generated HMPV VLP in baculovirus expression system. After three times immunization, IgG antibody titers induced by VLP formulated with or without alum adjuvant group were 273,066 ± 100,331 and 136,533 ± 47,269 respectively, there was no difference (p ˃ 0.05); the neutralizing antibody titers vaccinated with VLP plus with alum adjuvant (266 ± 92) were higher than those of the VLP alone group (106 ± 37). For IFN-γ, mice vaccinated with VLP with or without alum adjuvant are 151 ± 36.4 and 77.0 ± 17.1SFC/106 respectively, there was difference (p = 0.03); For IL-4, they are 261.3 ± 38.7 versus 125.67 ± 29.78SFC/106 respectively, the difference was significant (p = 0.009). After challenge, in pathological analysis, the overall lesion scores in the VLP plus with and without alum adjuvant were 3.25 and 5.6 respectively, those of control group is 8. For immunohistochemical analyses, the average optical density of the lungs in the VLP immunized group containing adjuvant (9.07 ± 1.74) was lower than that in the VLP group without adjuvant (12.83 ± 2.31, p = 0.14).

CONCLUSIONS

This is the first study to demonstrate that HMPV VLP was successfully prepared in the baculovirus expression system. HMPV VLP could induce specific humoral and cellular immune responses as well as protective efficacy, and aluminum hydroxide may be an effective adjuvant in mice.

Exploring the Potential of Nanotechnology in Pediatric Healthcare: Advances, Challenges, and Future Directions

The utilization of nanotechnology has brought about notable advancements in the field of pediatric medicine, providing novel approaches for drug delivery, disease diagnosis, and tissue engineering. Nanotechnology involves the manipulation of materials at the nanoscale, resulting in improved drug effectiveness and decreased toxicity. Numerous nanosystems, including nanoparticles, nanocapsules, and nanotubes, have been explored for their therapeutic potential in addressing pediatric diseases such as HIV, leukemia, and neuroblastoma. Nanotechnology has also shown promise in enhancing disease diagnosis accuracy, drug availability, and overcoming the blood-brain barrier obstacle in treating medulloblastoma. It is important to acknowledge that while nanotechnology offers significant opportunities, there are inherent risks and limitations associated with the use of nanoparticles. This review provides a comprehensive summary of the existing literature on nanotechnology in pediatric medicine, highlighting its potential to revolutionize pediatric healthcare while also recognizing the challenges and limitations that need to be addressed.

Non-COVID-19 respiratory viral infection

Implemented control measures brought about by the coronavirus disease 2019 (COVID-19) pandemic have changed the prevalence of other respiratory viruses, often relegating them to a secondary plan. However, it must not be forgotten that a diverse group of viruses, including other human coronaviruses, rhinoviruses, respiratory syncytial virus, human metapneumoviruses, parainfluenza and influenza, continue to be responsible for a large burden of disease. In fact, they are among the most common causes of acute upper and lower respiratory tract infections globally. Viral respiratory infections can be categorised in several ways, including by clinical syndrome or aetiological agent. We describe their clinical spectrum. Distinctive imaging features, advances in microbiological diagnosis and treatment of severe forms are also discussed.

Non-COVID-19 respiratory viral infections are a major burden of disease. Emerging molecular-based detection methods and knowledge of viral lower respiratory tract infections’ distinctive features improve diagnosis, treatment and outcome of severe forms.https://bit.ly/3qMqk3T

Human metapneumovirus-associated community-acquired pneumonia in adults during the first wave of COVID-19

Objective: The clinical course of human metapneumovirus (hMPV) infection is similar to that of coronavirus 2019 disease (COVID-19). However, community-acquired hMPV infections in adults have not yet been sufficiently investigated. We examined the detection status of hMPV antigens and the clinical features of positive patients during the first wave of COVID-19, which coincided with the epidemic season of hMPV infection in Japan.

Methods: In this cross-sectional, observational, and single-center study, we recruited consecutive individuals who visited the Japan Agricultural Cooperatives Kochi Hospital due to fever, respiratory symptoms, or close contact with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected persons during the period from January to May 2020.

Results: The positive rate of immunochromatography for hMPV antigens from nasopharyngeal swabs was 9.5% (4/42), and four positive cases were community-acquired pneumonia (CAP) (5.3% of all CAP). The positive rate of hMPV antigens in the CAP group (30.8%, 4/13) was higher than that in the non-pneumonia group (0.0%, 0/19) (p < 0.05). The average age of the four adult patients with CAP was 69.8 years (range 35–93). Mean white blood cell counts and C-reactive protein blood levels were 6,250 cells/μL (3,500–12,180) and 4.30 mg/dL (4.05–7.04), respectively. Chest computed tomography images were diverse and two patients showed dense consolidation. No multi-organ disorder was noted during the clinical course in any of the four cases, and their prognoses were good.

Conclusion: hMPV infection may be considered in the differential diagnosis of COVID-19 and CAP in Japan under the preventive measures for SARS-CoV-2 infection, at least during the epidemic season of hMPV infection.