Distribution Of Rabies Virus Research Articles

Geographic Distribution of Rabies Virus and Genomic Sequence Alignment of Wild and Vaccine Strains, Kenya.

Rabies, a viral disease that causes lethal encephalitis, kills ≈59,000 persons worldwide annually, despite availability of effective countermeasures. Rabies is endemic in Kenya and is mainly transmitted to humans through bites from rabid domestic dogs. We analyzed 164 brain stems collected from rabid animals in western and eastern Kenya and evaluated the phylogenetic relationships of rabies virus (RABV) from the 2 regions. We also analyzed RABV genomes for potential amino acid changes in the vaccine antigenic sites of nucleoprotein and glycoprotein compared with RABV vaccine strains commonly used in Kenya. We found that RABV genomes from eastern Kenya overwhelmingly clustered with the Africa-1b subclade and RABV from western Kenya clustered with Africa-1a. We noted minimal amino acid variances between the wild and vaccine virus strains. These data confirm minimal viral migration between the 2 regions and that rabies endemicity is the result of limited vaccine coverage rather than limited efficacy.

Genetic characteristics and geographic distribution of rabies virus in China.

China is one of the largest countries with endemic rabies. In this study, we examined the full-length genome sequences of 87 rabies virus (RABV) strains identified in China from 1931 to 2019. Chinese RABV isolates were divided into two major clades, GI and GII. Clade GI consisted of viruses from the Asian clade, which was further divided into three subclades: Asian1, Asian2, and Asian3. Clade GII consisted of viruses from the Cosmopolitan, Arctic-related, and Indian clades. A phylogeographic network showed that the variation of rabies virus was more closely associated with geographic location than with the host species. Recombination appears to be one of the factors driving the emergence of new viral strains.

Large-scale phylogenetic analysis reveals genetic diversity and geographic distribution of rabies virus in South-East and South Asia.

South-East Asia (SEA) and South Asia (SA) are two important geographic regions with the most severe enzootic rabies in the world. In these regions, phylogenetic analysis of rabies virus (RABV) has been conducted only at a country level; the results obtained from different countries are scattered and unequal, with a non-uniform system to name RABV genotypes. Therefore, it is difficult to undertake origin-tracking and compare inter-country RABV evolution and transmission. To avoid the confusion in understanding and to generate a panoramic picture of RABV genetic diversity, distribution, and transmission in SEA and SA, the present study conducted a systematic phylogenetic analysis by combining all sequences representing 2368 RABV strains submitted to GenBank by 14 rabies endemic SEA and SA countries. The results showed that RABVs circulating in two regions were classified into four major clades and many subclades: the Asia clade is circulating only in SEA, the Indian subcontinent, and Arctic-like clades only in SA, while the Cosmopolitan clade has been detected in both regions. The results also showed a wide range of hosts were infected by divergent RABV subclades, with dogs being the major transmission source. However, wildlife rabies was also found to be an important issue with 6 wild carnivore species identified as potential sources of spillover risk for sylvatic rabies to humans, domestic animals, and other wild animals. Current findings indicate that the two regions have separate virus clades circulating thus indicating the absence of cross-transmission between the regions. The study emphasizes the importance of phylogenetic analysis in the regions using uniform genotyping and naming systems for rabies surveillance, to coordinate actions of member countries to eliminate dog-mediated human rabies by 2030.

Aptamer and RVG functionalized gold nanorods for targeted photothermal therapy of neurotropic virus infection in the mouse brain

The infection of the neurotropic virus damages the central nervous system (CNS) and often leads to humans' fatal symptoms. Rabies is a lethal disease caused by a typical neurotropic virus, rabies virus (RABV). To date, there is no effective clinical therapy for rabies. In this report, an aptamer conjugated RVG-Apt-PEG-Silica gold nanorods (AuNR)-based photothermal therapy (PTT) was developed and evaluated in a mouse model. The DNA aptamer was conjugated on the nanoparticle to provide specificity for targeting RABV glycoprotein in cells and mouse brains. A 29-aa rabies virus glycopeptide (RVG) was conjugated on the nanoparticle to enhance CNS delivery. The virions were inactivated in cell supernatant, and an approximately 100-fold decrease of viral load was observed in cells 5 min post-PTT. This AuNR did not cause distinct apoptosis, inflammation, or pathological lesion in the mouse brains post PTT. At 3 day post-infection, significantly enhanced survival ratio (60%) was observed in mice received PTT compared with the mice without PTT. In the PTT group, both the viral RNA level and the distribution of RABV in mouse brains were significantly decreased. Collectively, aptamer conjugated RVG-Apt-PEG-Silica AuNR-based PTT could be considered as a promising strategy for clinical treatment with neurotropic virus infection.

Animal Rabies Surveillance, China, 2004-2018.

Rabies is a severe zoonotic disease in China, but the circulation and distribution of rabies virus (RABV) within animal reservoirs is not well understood. We report the results of 15 years of surveillance of the first Chinese Rabies Surveillance Plan in animal populations, in which animal brain tissues collected during 2004–2018 were tested for RABV and phylogenetic and spatial–temporal evolutionary analyses performed using obtained RABV sequences. The results have provided the most comprehensive dataset to date on the infected animal species, geographic distribution, transmission sources, and genetic diversity of RABVs in China. In particular, the transboundary transmission of emerging RABV subclades between China and neighboring countries was confirmed. The study highlights the importance of continuous animal rabies surveillance in monitoring the transmission dynamics, and provides updated information for improving current control and prevention strategies at the source.

High-Resolution 3D Imaging of Rabies Virus Infection in Solvent-Cleared Brain Tissue.

The visualization of infection processes in tissues and organs by immunolabeling is a key method in modern infection biology. The ability to observe and study the distribution, tropism, and abundance of pathogens inside of organ tissues provides pivotal data on disease development and progression. Using conventional microscopy methods, immunolabeling is mostly restricted to thin sections obtained from paraffin-embedded or frozen samples. However, the limited 2D image plane of these thin sections may lead to the loss of crucial information on the complex structure of an infected organ and the cellular context of the infection. Modern multicolor, immunostaining-compatible tissue clearing techniques now provide a relatively fast and inexpensive way to study high-volume 3D image stacks of virus-infected organ tissue. By exposing the tissue to organic solvents, it becomes optically transparent. This matches the sample's refractive indices and eventually leads to a significant reduction of light scattering. Thus, in combination with long free working distance objectives, large tissue sections up to 1 mm in size can be imaged by conventional confocal laser scanning microscopy (CLSM) at high resolution. Here, we describe a protocol to apply deep-tissue imaging after tissue clearing to visualize rabies virus distribution in infected brains in order to study topics like virus pathogenesis, spread, tropism, and neuroinvasion.

Spatiotemporal distribution of a non-haematophagous bat community and rabies virus circulation: a proposal for urban rabies surveillance in Brazil.

In Brazil, rabies surveillance is based on monitoring domestic and wild animals, although the most prevalent lineage of the rabies virus (RABV) currently diagnosed in Brazil is associated with bats, particularly non-haematophagous bats. Disease control is based on the mass vaccination of dogs and cats. We used data collected by the passive surveillance system of the city of Campinas from 2011 to 2015, to describe the temporal and geographic distributions of the bat specimens and RABV and discuss the current rabies surveillance with the advent of the declaration of canine and feline rabies-free areas in Brazil. We described the species, locations and health statuses of the collected bat specimens. Moreover, all samples were submitted for RABV diagnosis. Then, we performed a time series decomposition for each bat family. Additionally, we determined the spatiotemporal relative risk for RABV infection using the ratio of the kernel-smoothed estimates of spatiotemporal densities of RABV-positive and RABV-negative bats. From the 2537 bat specimens, the most numerous family was Molossidae (72%), followed by Vespertilionidae (14%) and Phyllostomidae (13%). The bat families behaved differently in terms of seasonal and spatial patterns. The distribution of bats varied geographically in the urban environment, with Molossidae and Phyllostomidae being observed downtown and Vespertilionidae being observed in peripheral zones. Concurrently, a significant relative risk of RABV infection was observed downtown for Vespertilionidae and in peripheral zones for Molossidae. No RABV-positive sample clusters were observed. As a result of the official declaration of RABV-free areas in southern Brazil, mass dog and cat vaccinations are expected to halt in the near future. This stoppage would make most dog and cat populations susceptible to other RABV lineages, such as those maintained by non-haematophagous bats. In this scenario, all information available on bats and RABV distribution in urban areas is essential. Currently, few studies have been conducted. Some local health authorities, such as that in Campinas, are spontaneously basing their surveillance efforts on bat rabies, which is the alternative in reality scenario of increased susceptibility to bat-associated RABV that is developing in Brazil.

Rabies virus distribution in tissues and molecular characterization of strains from naturally infected non-hematophagous bats

Bats are main reservoirs for Lyssavirus worldwide, which is an important public health issue because it constitutes one of the big challenges in rabies control. Yet, little is known about how the virus is maintained among bats, and the epidemiological relationships remain poorly understood. The aim of the present study was to investigate the distribution of the rabies virus (RABV) in bat tissues and organs and to genetically characterize virus isolates from naturally infected non-hematophagous bats. The heminested reverse transcriptase polymerase chain reaction (hnRT-PCR) and sequencing using primers to the nucleoprotein coding gene were performed. The results showed a dissemination of the RABV in different tissues and organs, particularly in the salivary glands, tongue, lungs, kidneys, bladder, intestine and feces, suggesting other possible forms of RABV elimination and the possibility of transmission among these animals. The phylogenetic analysis confirmed that different variants of RABV are maintained by non-hematophagous bats in nature and have similar tissue distribution irrespective of bat species and phylogenetic characterization.

Study on the status of infection and distribution of rabies virus in China

To investigate the status of infection and distribution of rabies virus (RV) in different epidemic areas in China. Brain specimens from animals and suspected patients were collected at the districts of high-, medium- and low incidence rates of human rabies and detected by both direct Immunofluorescence assay (DFA) and RT-PCR. 254 of 3007 specimens of dog brains showed RV positive by DFA (positive rate of 8.4%). Among these 254 samples, 78 showed positive (positive rate of 30.7%) by RT-PCR. 93 specimens from dogs and cats that had attacked human beings, 63 of them showed positive by DFA (positive rate of 67.7%) and all of them were also positive by RT-PCR. In addition, RV could also be detected in Apodemus agrarius, ferret badger, and suspected patients specimens from the districts under survey. There was no statistical difference between the infection rates of RV in different provinces and regions with different incidence of rabies. There might be a relatively high infection rate of RV among the domestic dogs/cats in the endemic areas in China. Wild animals might have been infected with RV in the districts under survey.

Molecular epidemiology investigation of rabies virus nucleoprotein genes in China

To study the relationship between the distribution of rabies virus and genetic variation, the genetic characterization and variation of rabies virus strains in China were analyzed. The downstream 720 nucleotides of Nucleoprotein (N) gene coding region of the rabies specimens from different areas and host animals were sequenced, and then homology and phylogenesis were analyzed. Nucleotide similarities of 34 N gene sequences were 87.5%-100%, and the deduced amino acid similarities were 93.3%-99.6%. Most of the nucleotide variations were synonymous mutations. The 34 rabies specimens all belong to genotype I and are of regional characteristic. The rabies viruses in high-incidence areas in China are of various origins and present the transmission tendency from high-incidence areas to surrounding regions. There may be cross-infection and mutual spread of rabies virus between wildlife and domestic animals as well as native and foreign animals.

Correlation of cytokine expression with rabies virus distribution in rabies encephalitis

Rabies encephalitis is a significant health hazard, particularly in Asia. To understand the role of immune mechanisms and cytokines in rabies encephalitis, we performed a retrospective and prospective study on the autopsy material. Representative histopathological sections were studied and subjected to immunostaining for rabies virus antigen, TNF-α and IL-1β. Immunohistochemistry for IL-1β and TNF-α revealed expression of these cytokines in 96% of cases in microglial cells, macrophages and lymphocytes with a strong positive correlation between IL-1β and TNF-α immunopositivity and degree of perivascular and parenchymal inflammation. In addition, expression of IL-1β and TNF-α also correlated positively with each other. However there was no direct correlation of viral antigen load with grading of cytokine expression. These findings indicate that IL-1β and TNF-α together may play an important role to coordinate the dramatic inflammatory response associated with the rabies-encephalopathy. They may serve as important targets for future therapy.

The heminested RT-PCR for the study of rabies virus pathogenesis

The aim of the present trial was to evaluate the heminested RT-PCR for the study of rabies virus distribution in mice inoculated experimentally. Inoculation was by the intramuscular route in 150 mice, using the dog street rabies virus. Groups of five animals were killed at different times. Fragments of different organs were collected and the material was tested by Fluorescent Antibody Test (FAT) and heminested RT-PCR (hn RT-PCR). Positive results were obtained beginning on the 10th day after inoculation in the brain, spinal cord, salivary gland, limbs, lungs, liver, spleen, urinary bladder, tongue and right kidney. Hn RT-PCR was shown to be more efficient for the study of rabies virus distribution in different tissues and organs.

Distribution of rabies virus in infected mice, vaccinated and submitted to P.acnes as immunomodulator

The lethality and distribution of rabies virus were evaluated in swiss mice experimentally infected with street rabies virus, vaccinated and submitted to immunomodulation by P.acnes (formerly Corynebacterium parvum). The animals were sacrificed at different times,when the different tissues were collected and submitted to fluorescent antibody test (FAT) and mouse inoculation test (MIT). The group submitted to vaccination and P.acnes treatment presented a percentage of survival superior to that observed in infected mice only treated with P.acnes. Control infected animals had the lowest survival rates.The distribution of rabies virus in spleen of infected mice, vaccinated and submitted to P.acnes was superior to that verified in infected mice not treated with P.acnes. The increased survival correlated with the distribution of rabies virus in lymphoid tissues, could be interpreted as the consequence of P.acnes activity on macrophages. The results suggest the role of macrophages against rabies virus infection in mice and the importance of vaccination in the post expositive treatment of rabies.

Antigenic diversity and distribution of rabies virus in Mexico.

Rabies remains a public health problem in the Americas because of the great diversity of wild reservoirs that maintain the virus in nature. Here we report the antigenic characterization of 254 rabies viruses isolated from 148 nonreservoir and 106 reservoir hosts collected in 27 states of Mexico. Nine out of 11 antigenic variants previously reported in the United States were detected in Mexico by using the limited panel of monoclonal antibodies donated by the Centers for Disease Control and Prevention. Some rabies virus variants were isolated from their natural reservoirs, which were also taxonomically identified. Terrestrial reservoirs included stray dogs with V1, Urocyon cineroargenteus (gray foxes) with V7, and two subspecies of Spilogale putorius (spotted skunks) with different viral variants (V8 and V10). Aerial hosts included Tadarida brasiliensis mexicana and Desmodus rotundus, which harbored V9 and V4 and harbored V11, respectively. All variants, with the exception of V9, were isolated from nonreservoir hosts, while V3, V4, and V5 were not isolated from their natural reservoirs but only from livestock. Rabies virus antigenic typing allowed us to determine rabies reservoirs and their distribution in Mexico, data which will probably improve prevention and control of the illness in humans and in the reservoir hosts.

Distribution of rabies virus, interferon and interferon-mediated enzymes in the brains of virus-infected rats.

The distribution of rabies virus, interferon and interferon-mediated enzymes, pppA(2'p5'A)n synthetase (2-5A synthetase) and poly(rI) . poly(rC)-Sepharose-bound protein kinase, was studied in different regions of the brains of rabies virus-infected rats. A broad range of virus infectivity was found in the brain stem, cerebellum, cortex, hippocampus and striatum. Similarly, the levels of interferon were variable (2500 to 60 000 units/mg protein in tissue extracts) in the different brain regions studied but were unrelated to the corresponding infectivities . The level of 2-5A synthetase and protein kinase was enhanced several-fold in the individual brain regions and the degree of such enhancement was correlated with the level of interferon.