Detection of Apparent Early Rabies Infection by LN34 Pan-Lyssavirus Real-Time RT-PCR Assay in Pennsylvania

Reemergence of a Big Brown Bat Lyssavirus rabies Variant in Striped Skunks in Flagstaff, Arizona, USA, 2021-2023

Background: Throughout the Americas, Lyssavirus rabies (RV) perpetuates as multiple variants among bat and mesocarnivore species. Interspecific RV spillover occurs on occasion, but clusters and viral host shifts are rare. The spillover and host shift of a big brown bat (Eptesicus fuscus) RV variant Ef-W1 into mesocarnivores was reported previously on several occasions during 2001-2009 in Flagstaff, Arizona, USA, and controlled through rabies vaccination of target wildlife. During autumn 2021, a new cluster of Ef-W1 RV cases infecting striped skunks (Mephitis mephitis) was detected from United States Department of Agriculture enhanced rabies surveillance in Flagstaff. The number of Ef-W1 RV spillover cases within a short timeframe suggested the potential for transmission between skunks and an emerging host shift. Materials and Methods: Whole and partial RV genomic sequencing was performed to evaluate the phylogenetic relationships of the 2021-2023 Ef-W1 cases infecting striped skunks with earlier outbreaks. Additionally, real-time reverse-transcriptase PCR (rtRT-PCR) was used to opportunistically compare viral RNA loads in brain and salivary gland tissues of naturally infected skunks. Results: Genomic RV sequencing revealed that the origin of the 2021-2023 epizootic of Ef-W1 RV was distinct from the multiple outbreaks detected from 2001-2009. Naturally infected skunks with the Ef-W1 RV showed greater viral RNA loads in the brain, but equivalent viral RNA loads in the mandibular salivary glands, compared to an opportunistic sample of skunks naturally infected with a South-Central skunk RV from northern Colorado, USA. Conclusion: Considering a high risk for onward transmission and spread of the Ef-W1 RV in Flagstaff, public outreach, enhanced rabies surveillance, and control efforts, focused on education, sample characterization, and vaccination, have been ongoing since 2021 to mitigate and prevent the spread and establishment of Ef-W1 RV in mesocarnivores.

Evaluation of LN34 Pan-Lyssavirus RT-qPCR assay for rabies diagnosis in Brazil

Rabies, a fatal zoonotic viral disease affecting mammals, including humans, remains a significant global health concern, particularly in low-income countries. The disease, primarily transmitted through infected animal saliva, prompts urgent diagnosis for timely post-exposure prophylaxis (PEP). The gold standard diagnostic test, direct fluorescent antibody test (dFAT), while sensitive, suffers from limitations such as subjective interpretation and high costs. As a confirmatory technique, the LN34 Pan-Lyssavirus RT-qPCR assay has emerged as a promising tool for universal Lyssavirus detection. This study evaluated its performance using 130 rabies virus isolates representing eleven Brazilian variants and 303 clinical samples from surveillance operations. The LN34 assay demonstrated 100% sensitivity and 98% specificity compared to dFAT. Additionally, it detected all samples, including those missed by dFAT, indicating superior sensitivity. The assay's specificity was confirmed through Sanger nucleotide sequencing, with only a minimal false-positive rate. Comparative analysis revealed higher accuracy and concordance with dFAT than traditional rabies tissue culture infection tests (RTCIT). False-negative RTCIT results were attributed to low viral load or suboptimal sampling. These findings underscore the LN34 assay's utility as a confirmatory technique, enhancing rabies surveillance and control in Brazil. Its widespread adoption could significantly improve diagnostic sensitivity, crucial for effective PEP and public health interventions.

Comparing the genetic typing methods for effective surveillance and rabies control in Georgia

A full nucleoprotein gene sequencing of 68 isolates collected from passive rabies surveillance system in Georgia between 2015 and 2016 identified two distinct dog rabies phylogroups, GEO_V1 and GEO_V2, which both belonged to the cosmopolitan dog clade. GEO_V1 was found throughout the country and was further divided into four sub-phylogroups that overlapped geographically; GEO_V2 was found in the southeast region and was closely related to dog rabies in Azerbaijan. A sequence analysis of the full N gene, partial nucleoprotein gene of N-terminal and C-terminal, and the amplicon sequences of pan-lyssavirus RT-qPCR LN34 showed that all four sequencing approaches provided clear genetic typing results of canine rabies and could further differentiate GEO_V1 and GEO_V2. The phylogenetic analysis results vary and were affected by the length of the sequences used. Amplicon sequencing of the LN34 assay positive samples provided a rapid and cost-effective method for rabies genetic typing, which is important for improving rabies surveillance and canine rabies eradication globally.

Special Issue "Advances in Rabies Research"

Rabies kills approximately 60,000 humans each year, with deaths mostly occurring in developing countries, where rabies lyssavirus (RABV) variants are maintained in dog populations [...].