Identification of Novel Rodent-Borne Orthohantaviruses in an Endemic Area of Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka

Coinfection with Orthohantavirus and Leptospira spp. in Rats Collected from Markets in Indonesia

Background: Rats are an important reservoir animal for several zoonotic pathogens worldwide, including hantaviruses and Leptospira spp., which are the causative agents of hemorrhagic fever with renal syndrome, hantavirus cardiopulmonary syndrome, and leptospirosis. Although a previous study indicated a high frequency of antihantaviral antibodies in patients with acute fever in Indonesia, circulating hantaviruses and their reservoir animals in the country remain limited. Materials and Methods: The presence of hantavirus in rats captured in the urban area of Bogor, Indonesia, from which Leptospira spp. were isolated using PCR, followed by DNA sequencing. Immunohistochemical analyses were performed to detect hantaviral and leptospiral antigens in rat kidney tissues. Results: Seoul of Orthohantavirus seoulense (SEOV) RNA was detected from 24 of 80 Rattus norvegicus (30%). SEOV and Leptospira coinfection was detected in 10 of 80 rats (12.5%). Immunohistochemistry revealed that hantavirus antigens were positively stained in the interstitial capillaries and cells, whereas Leptospira antigens were stained in the luminal side of the renal tubules. Conclusion: This study revealed a high prevalence of SEOV and SEOV and Leptospira coinfection among rats in the urban areas of Bogor, Indonesia, indicating a potential risk of rat-borne zoonotic diseases in the area.

Pending Reorganization of Hantaviridae to Include Only Completely Sequenced Viruses: A Call to Action

The official classification of newly discovered or long-known unassigned viruses by the International Committee on Taxonomy of Viruses (ICTV) requires the deposition of coding-complete or -near-complete virus genome sequences in GenBank to fulfill a requirement of the taxonomic proposal (TaxoProp) process. However, this requirement is fairly new; thus, genomic sequence information is fragmented or absent for many already-classified viruses. As a result, taxon-wide modern phylogenetic analyses are often challenging, if not impossible. This problem is particularly eminent among viruses with segmented genomes, such as bunyavirals, which were frequently classified solely based on single-segment sequence information. To solve this issue for one bunyaviral family, Hantaviridae, we call on the community to provide additional sequence information for incompletely sequenced classified viruses by mid-June 2023. Such sequence information may be sufficient to prevent their possible declassification during the ongoing efforts to establish a coherent, consistent, and evolution-based hantavirid taxonomy.

Evidence of orthohantavirus and leptospira infections in small mammals in an endemic area of Gampaha district in Sri Lanka

BACKGROUND

Orthohantaviruses and leptospira are emerging zoonotic pathogens of high public health significance. The epidemiology of orthohantavirus infections and leptospirosis is similar and presents related clinical pictures in humans. However, a paucity of data on actual reservoir hosts for orthohantaviruses and leptospira exists. Therefore, this study aimed at determining the occurrence of orthohantaviruses and leptospira in small mammals captured in an endemic region of Sri Lanka.

METHODS

Rodents and shrews were morphologically and/or genetically identified using morphological keys and DNA barcoding techniques targeting the cytochrome oxidase b subunit gene (Cytb). Lung tissues and sera were subsequently analyzed for the presence of orthohantavirus RNA using qRT-PCR. Sera of rats were tested for IgG antibodies against orthohantaviruses and leptospira.

RESULTS

Forty-three (43) small mammals representing: Rattus (R.) rattus (black rat) or R. tanezumi (Asian rat), Suncus murinus (Asian house shrew), R. norvegicus (brown rat) and Mus musculus (house mouse) were investigated. No orthohantavirus RNA was detected from the lung tissue or serum samples of these animals. Elevated levels of IgG antibodies against Puumala orthohantavirus (PUUV) and/or Seoul orthohantavirus (SEOV) antigens were detected in sera of 28 (72%) out of the 39 rats analysed. Interestingly, 36 (92%) of the 39 rats also showed presence of anti leptospira-IgG antibodies in their serum, representing dual infection or dual exposure in 26/39 (66.7%) of examined rats.

CONCLUSIONS

This project targets important public health questions concerning the occupational risk of orthohantavirus infections and/or leptospirosis in an endemic region of Sri Lanka. Most rats (72%) in our study displayed antibodies reacting to orthohantavirus NP antigens, related to PUUV and/or SEOV. No correlation between the orthohantavirus and leptospira IgG antibody levels were noticed. Finally, a combination of both morphological and DNA barcoding approaches revealed that several species of rats may play a role in the maintenance and transmission of orthohantavirus and leptospira in Sri Lanka.