The severity of MeV infection has been greatly reduced by the development of a live attenuated vaccine, which has been incorporated into vaccination programs in many countries. However, poor access to health facilities, and above all, the increase in anti-vaccination movements, has prevented the achievement of sufficient vaccination coverage. In outbreak scenarios, a rapid and transportable method can improve differential diagnosis, including removing ambiguity in suspected measles cases, contacts, or a cohort. In response to the need, we have developed a new RT-qPCR-based MeV detection assay. The LOD of the developed assay was determined on different PCR machines and the higher threshold was 1–1.2 10³ copies/mL. The joint diagnostic sensitivity of ELISA and RT-PCR (used together) was 100%, and used combinedly, these two methods enable detection of all measles-infected persons, which is extremely important for controlling contagion and spread of infection. During the clinical validation of the assay on 200 clinical samples from measles-suspected cases using ELISA, 157 samples showed a positive result, while 163 positive cases were confirmed by the RT-qPCR assay. The concordance between the two techniques was 93%. According to our results, the real-time RT-PCR approach used in our study is more sensitive and appears to be a more promising method for measles diagnosis during early stages of the disease, likely before the rise of specific IgM antibodies detected by ELISA.

In this report, we document and analyze a case in which the Irkut virus (IRKV) (Mononegavirales: Rhabdoviridae) caused a fatal human case following a bat bite in June 2021. Unfortunately, the available data did not permit a detailed taxonomic classification of the carrier bat (Chiroptera). The event occurred in the southwestern part of the Sikhote-Alin mountain region (Russian Far East) covered by the Ussuri taiga forest. The symptoms of the illness began with the following: fever; pronounced psychomotor and motor agitation; tremor of the lower jaw and tongue; aphasia; dyslexia; and dysphagia. These rapidly developed, leading to a severe and fatal encephalitis. The patient was not vaccinated for rabies and did not receive rabies immunoglobulin. Using brain sections prepared from the deceased, molecular diagnostics were performed: immunofluorescence (polyclonal anti-rabies immunoglobulin) indicating the presence of the lyssavirus antigen; and RT-PCR indicating traces of viral RNA. Sectional material (brain) was used for whole-genome sequencing, resulting in a near-complete sequence of the lyssavirus genome. The obtained genomic sequence was identified as the Irkut virus. A comparative analysis of the new sequence and other currently available IRKV sequences (NCBI) revealed differences. Specifically, amino acid differences between antigenic sites in the isolate and those of the rabies vaccine strain used regionally were noted. The patient history and subsequent analysis confirm human IRKV infection following bat contact. Like other fatal cases of IRKV infection described earlier, this case occurred in the southern part of the Russian Far East. Two have occurred in the southwestern part of the Sikhote-Alin mountain region. This indicates the possible existence of an active, natural viral focus.

Arboviruses, including but not limited to dengue virus (DENV), Zika virus (ZIKV), and chikungunya virus (CHIKV), pose a significant global threat to human health. The transmission of DENV, ZIKV, and CHIKV is facilitated by mosquitoes belonging to the genus Aedes, which are prevalent in both urban and rural regions of Vietnam. In 2023 an investigation into the population of mosquitoes was conducted in a number of provinces located within the central region of Vietnam. A total of 12,546 mosquitoes were collected during the study. The mosquitoes collected comprised the genera Culex spp., Aedes spp., Anopheles spp., and Armigeres spp. The Aedes spp. mosquitoes were predominant, being collected in 908 pools. These were then examined by RT-qPCR for the detection of DENV, ZIKV, and CHIKV. DENV viral RNA was detected in 92 mosquito pools, ZIKV was detected in 1 mosquito pool, and CHIKV was not detected. The typing of samples containing DENV RNA was carried out. It is evident from the results of the typing process that three distinct types of DENV have been identified. The three main dengue virus types are DENV-1, DENV-2, and DENV-4.

Mosquitoes are important vectors for various infectious pathogens. More than 200 species of mosquitoes are common in Vietnam, one of the main carriers of viruses that are important for humans is the mosquito of the genus Aedes aegypti. Metavirome sequencing can shed light on the diversity of mosquito-borne viruses classified as insect-specific viruses (ISV). After BLAST analysis using the viral database, contigs were classified as belonging to seventeen ISVs. Ten of them are distributed among five families: Totiviridae; Flaviviridae; Partitiviridae; Phenuiviridae; and Orthomyxoviridae. The other seven species belonged to recently identified RNA viruses whose taxonomic position is undefined in the current classification of the International Committee on Taxonomy of Viruses (ICTV). This is the first study to reveal the diversity of RNA viruses associated with Aedes aegypti mosquitoes in Vietnam, while highlighting the need for further study of ISV in mosquito vectors.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been responsible for over two years of the COVID-19 pandemic and a global health emergency. Genomic surveillance plays a key role in overcoming the ongoing COVID-19 pandemic despite its relative successive waves and the continuous emergence of new variants. Many technological approaches are currently applied for the whole genome sequencing (WGS) of SARS-CoV-2. They differ in key stages of the process, and they feature some differences in genomic coverage, sequencing depth, and in the accuracy of variant-calling options. In this study, three different protocols for SARS-CoV-2 WGS library construction are compared: an amplicon-based protocol with a commercial primer panel; an amplicon-based protocol with a custom panel; and a hybridization capture protocol. Specific differences in sequencing depth and genomic coverage as well as differences in SNP number were found. The custom panel showed suitable results and a predictable output applicable for the epidemiological surveillance of SARS-CoV-2 variants.

Background: Tick-borne encephalitis virus (TBEV, Orthoflavivirus encephalitidis ) is an arbovirus of the family Flaviviridae. It is the etiological agent of tick-borne encephalitis (TBE), a severe disease affecting the central nervous system. Among arboviral infections, TBE represents the greatest burden in northern Eurasia, both in terms of emerging infection risk and mortality. Globalization and climate change increase the risk of TBEV introduction into nonendemic countries. They may also lead to the emergence of new viral variants featuring increased virulence for humans or altered antigenic characteristics. Hence, sensitive and specific TBEV detection methods are needed not only for diagnostics but also for One Health approach goals (surveillance and identification of viral sources in the environment). Methods: Here, we describe a newly developed reverse transcription PCR (RT‒PCR) assay for TBEV detection. The assay was developed and evaluated using armored RNA positive control particles (ARCs). The assay was evaluated using several sample types: (1) a panel of heterologous viral and bacterial RNA/DNA; (2) RNA from TBEV strains isolated in different years in various Russian regions; and (3) RNA from TBEV-positive and TBEV-negative ticks (collected in northwest Russia). Results: The limit of detection (LOD) of the assay is 10 ³ copies/mL (20 copies/reaction) of TBEV RNA. The developed demonstrated 100% analytical specificity. The assay was compared with the two most commonly used Russian commercial kits for TBEV diagnostics. Conclusions: The results indicate that the developed RT‒PCR assay is a reliable and competitive method for the detection of TBEV RNA, which establishes its value as a tool for diagnosing and monitoring the virus. Graphical