Re-emergence of rabies in the Guangxi province of Southern China

Apolipoprotein D facilitates rabies virus propagation by interacting with G protein and upregulating cholesterol

Rabies virus (RABV) causes a fatal neurological disease, consisting of unsegmented negative-strand RNA, which encodes five structural proteins (3'-N-P-M-G-L-5'). Apolipoprotein D (ApoD), a lipocalin, is upregulated in the nervous system after injury or pathological changes. Few studies have focused on the role of ApoD during virus infection so far. This study demonstrated that ApoD is upregulated in the mouse brain (in vivo) and C8-D1A cells (in vitro) after RABV infection. By upregulating ApoD expression in C8-D1A cells, we found that ApoD facilitated RABV replication. Additionally, Co-immunoprecipitation demonstrated that ApoD interacted with RABV glycoprotein (G protein). The interaction could promote RABV replication by upregulating the cholesterol level. These findings revealed a novel role of ApoD in promoting RABV replication and provided a potential therapeutic target for rabies.

Transcriptomic Analysis of mRNA Expression Profiles in the Microglia of Mouse Brains Infected with Rabies Viruses of Varying Virulence

Rabies is a lethal encephalitis caused by the rabies virus (RABV) with a fatality rate near 100% after the onset of clinical symptoms in humans and animals. Microglia are resident immune cells in the central nervous system. Few studies have been conducted on the functional role of microglia in RABV infection. Here, we performed a transcriptomic analysis of mRNA expression profiles in the microglia of mouse brains intracerebrally infected with RABV. We successfully isolated single microglial cells from the mouse brains. The survival rate of dissociated microglial cells was 81.91%-96.7%, and the purity was 88.3%. Transcriptomic analysis revealed 22,079 differentially expressed mRNAs identified in the microglia of mouse brains infected with RABV strains (rRC-HL, GX074, and CVS-24) of varying virulence at 4 and 7 days post-infection (dpi) compared to the control group. The numbers of DEGs versus the control at 4 and 7 dpi in mice infected with rRC-HL, GX074, and CVS-24 were 3622 and 4590, 265 and 4901, and 4079 and 6337. The GO enrichment analysis showed that response to stress, response to external stimulus, regulation of response to stimulus, and immune system process were abundant during RABV infection. The KEGG analysis indicated that the Tlr, Tnf, RIG-I, NOD, NF-κB, MAPK, and Jak-STAT signaling pathways were involved in RABV infection at both 4 and 7 dpi. However, some phagocytosis and cell signal transduction processes, such as endocytosis, p53, phospholipase D, and oxidative phosphorylation signaling pathways, were only expressed at 7 dpi. The involvement of the Tnf and Tlr signaling pathways prompted us to construct a protein-protein interaction (PPI) network of these pathways. The PPI revealed 8 DEGs, including Mmp9, Jun, Pik3r1, and Mapk12. Notably, Il-1b interacted with Tnf and Il-6 with combined scores of 0.973 and 0.981, respectively. RABV causes significant changes in mRNA expression profiles in the microglia in mice. 22,079 differentially expressed mRNAs were identified in the microglia of mice infected with RABV strains of varying virulence at 4 and 7 dpi. The DEGs were evaluated using GO, KEGG, and PPI network analysis. Many immune pathways were up-regulated in RABV-infected groups. The findings will help elucidate the microglial molecular mechanisms of cellular metabolism dysregulated by RABV and may provide important information for investigating RABV pathogenesis and therapeutic methods.

Host Desmin Interacts with RABV Matrix Protein and Facilitates Virus Propagation

Microfilaments and microtubules, two crucial structures of cytoskeletal networks, are usurped by various viruses for their entry, egress, and/or intracellular trafficking, including the Rabies virus (RABV). Intermediate filaments (IFs) are the third major component of cytoskeletal filaments; however, little is known about the role of IFs during the RABV infection. Here, we identified the IF protein desmin as a novel host interactor with the RABV matrix protein, and we show that this physical interaction has a functional impact on the virus lifecycle. We found that the overexpression of desmin facilitates the RABV infection by increasing the progeny virus yield, and the suppression of endogenous desmin inhibits virus replication. Furthermore, we used confocal microscopy to observe that the RABV-M co-localizes with desmin in IF bundles in the BHK-21 cells. Lastly, we found that mice challenged with RABV displayed an enhanced expression of desmin in the brains of infected animals. These findings reveal a desmin/RABV-M interaction that positively regulates the virus infection and suggests that the RABV may utilize cellular IFs as tracks for the intracellular transport of viral components and efficient budding.

Vaccination demonstration zone successfully controls rabies in Guangxi Province, China

BACKGROUND

Guangxi is the province most seriously affected by rabies virus (RABV) in China. Those most affected by RABV each year are people in rural areas, where dogs are the main cause of human infection with the virus.

METHODS

In this study, we established a rabies vaccination demonstration program that included eradication, core, and peripheral areas. This program was implemented for 9 years and comprised three stages: 12 counties in the first stage (2008-2010), 21 counties in the second stage (2011-2013), and then extending to all counties of Guangxi Province in the third stage (2014-2016). The program included a dog vaccination campaign, surveillance of clinically healthy dogs who may be potential RABV carriers, monitoring anti-RABV antibody titers in vaccinated dogs, and compiling and reporting statistics of human rabies cases.

RESULTS

The target effectiveness was achieved in the eradication, core, and peripheral areas in all three stages. The vaccination demonstration program successfully promoted RABV vaccination of domestic dogs throughout Guangxi Province by drawing upon the experience gained at key points. Compared with a vaccination coverage rate of 39.42-46.85% in Guangxi Province overall during 2003-2007, this rate gradually increased to 48.98-52.67% in 2008-2010, 60.24-69.67% in 2011-2013, and 70.09-71.53% in 2014-2016, thereby meeting World Health Organization requirements. The total cases of human rabies in the province decreased from 602 in 2004 to 41 cases in 2017.

CONCLUSIONS

The present pilot vaccination program obviously increased the rabies vaccination and seroconversion rates, and effectively reduced the spread of rabies from dogs to humans as well as the number of human rabies cases, thus successfully controlling rabies in Guangxi.

Evolutionary analysis of rabies virus isolates from Guangxi Province of southern China

Background

Rabies is a severe epidemic in Guangxi province, China, with hundreds of deaths occurring each year. In the past six decades, rabies has emerged three times in Guangxi, and the province has reported the largest number of rabies cases in China. The domestic dog is the principal vector for rabies, and 95% of human cases are associated with transmission from dogs.

Results

To understand the genetic relationship between street rabies virus (RABV) from Guangxi, genetic diversity analysis was performed using RABV isolates collected between 1999 and 2012. The N gene of 42 RABV isolates, and the P and M genes, as well as fragments of the 3′ terminus (L^1–680) and the polymerase activity module of the L gene (L^pam) of 36 RABV isolates were sequenced. In addition, whole genome sequencing was performed for 5 RABV isolates. There was evidence of topological discrepancy in the phylogenetic trees based on different genes of the RABV isolates. Amino acid variation of the deduced N protein exhibited different patterns to those obtained from the P and M proteins reported here, and the previously reported G protein (Tang H. et al., PLoS Negl Trop Dis, 8(10): e3114, 2014), and L^1–680 and L^pam. These RABV isolates were divided into three main branches against fixed strains.

Conclusion

RABV is prevalent in Guangxi province and strains collected over the last two decades belong mainly to three groups (I, II, III). These RABV isolates reveal genetic diversity. Individual RABV genes from Guangxi exhibit different evolutionary characteristics. The results will have benefits for continuing comprehensive rabies surveillance, prevention and control in China.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1514-0) contains supplementary material, which is available to authorized users.

Community-based interventions to enhance knowledge, protective attitudes and behaviors towards canine rabies: results from a health communication intervention study in Guangxi, China

BACKGROUND

In China canine rabies poses a serious public health problem in that human mortality ranks the second highest globally. While rabies health education interventions are advocated by WHO to be critical components of modern rabies control and prevention programs, available studies have not adequately investigated the relative efficacy of their implementation in at-risk populations. This study aims to measure and compare the effect on knowledge and protective behavior towards rabies of health education interventions that include a novel Short Messaging Service via cell phone (SMS) and rabies health information sessions (IS).

METHODS

The study used a between-subject design involving repeated measures of rabies-related KAP (knowledge, attitude and practice). A total of 350 randomly selected villagers were randomly allocated into three intervention (SMS, IS and SMS + IS) and one control group. The content of SMS and IS covered topics about rabies prevention and route of transmission. The SMS intervention consisted of ten separate messages delivered three times two weeks after the pretest; the IS intervention was conducted once immediately after the pretest. A validated questionnaire was used to capture demographic information and KAP information. Ordinary Least Squares regression was used to contrast the effects of interventions.

RESULTS

Our results indicate that overall SMS outperforms IS at improving knowledge and protective behavior against rabies. Our results suggest that a combined intervention of SMS and IS can result in higher scores than any of the two in isolation. The impact of SMS, IS and SMS + IS is greatest on knowledge, followed by attitude and practice scores.

CONCLUSION

This study demonstrated that health communication modes based on SMS, IS and a combination of the two are all effective to improve rabies-related KAP in the short term. These findings highlight the potential usefulness of SMS as an additional tool for public health communication and promotion; further studies are needed to investigate the long term benefits of these interventions on the reduction of dog bites and resulting human rabies incidence.

Viperin inhibits rabies virus replication via reduced cholesterol and sphingomyelin and is regulated upstream by TLR4

Viperin (virus inhibitory protein, endoplasmic reticulum-associated, IFN-inducible) is an interferon-inducible protein that mediates antiviral activity. Generally, rabies virus (RABV) multiplies extremely well in susceptible cells, leading to high virus titres. In this study, we found that viperin was significantly up-regulated in macrophage RAW264.7 cells but not in NA, BHK-21 or BSR cells. Transient viperin overexpression in BSR cells and stable expression in BHK-21 cells could inhibit RABV replication, including both attenuated and street RABV. Furthermore, the inhibitory function of viperin was related to reduce cholesterol/sphingomyelin on the membranes of RAW264.7 cells. We explored the up-stream regulation pathway of viperin in macrophage RAW264.7 cells in the context of RABV infection. An experiment confirmed that a specific Toll-like receptor 4 (TLR4) inhibitor, TAK-242, could inhibit viperin expression in RABV-infected RAW264.7 cells. These results support a regulatory role for TLR4. Geldanamycin, a specific inhibitor of interferon regulatory factor 3 (IRF3) (by inhibiting heat-shock protein 90 (Hsp90) of the IRF3 phosphorylation chaperone), significantly delayed and reduced viperin expression, indicating that IRF3 is involved in viperin induction in RAW264.7 cells. Taken together, our data support the therapeutic potential for viperin to inhibit RABV replication, which appears to involve upstream regulation by TLR4.