Incidence and seroprevalence of rabies virus in humans, dogs and other animal species in Africa, a systematic review and meta-analysis

Immunological findings of West Caucasian bat virus in an accidental host

The Lyssavirus genus includes seventeen viral species able to cause rabies, an acute and almost invariably fatal encephalomyelitis of mammals. Rabies virus (RABV), which represents the type species of the genus, is a multi-host pathogen that over the years has undergone multiple events of host-switching, thus occupying several geographical and ecological niches. In contrast, non-RABV lyssaviruses are mainly confined within a single natural host with rare spillover events. In this scenario, unveiling the mechanisms underlying the host immune response against a virus is crucial to understand the dynamics of infection and to predict the probability of colonization/adaptation to a new target species. Presently, the host response to lyssaviruses has only been partially explored, with the majority of data extrapolated from RABV infection. West Caucasian bat virus (WCBV), a divergent lyssavirus, has recently been associated with a spillover event to a domestic cat, raising concern about the risks to public health due to the circulation of the virus in its natural host. Through this study we have investigated the immune response determined by the WCBV versus two widely known lyssaviruses. We selected the Syrian hamster as representative of an accidental host, and chose the intramuscular route in order to mimic the natural infection. In hamsters, WCBV was highly pathogenic, determining 100% lethality and mild encephalitis. In comparison with Duvenhage virus (DUVV) and RABV, we found that WCBV displayed an intermediate ability to promote cellular antiviral response, produce pro-inflammatory cytokines, and recruit and activate lymphocytes in the hamsters' central nervous system.

IMPORTANCE

Although all lyssaviruses cause fatal encephalomyelitis in mammals, they display a different host tropism and pathogenicity, with the ecology of Rabies virus (RABV) continually evolving and adapting to new host species. In 2020, West Caucasian bat virus (WCBV) was identified as the causative agent of rabies in a domestic cat in Italy. This event raised concerns about its public health consequences, due to the absence of biologicals against the infection. Our study investigates the host immune response triggered by WCBV in comparison with a pathogenic strain of RABV and the low pathogenic Duvenhage lyssavirus (DUVV), as a proxy to understand the mechanisms leading to lyssavirus spillover and pathogenicity. We overall confirm that previous evidence indicating an inverse relationship between lyssavirus pathogenicity and immune response is applicable for WCBV as well. Importantly, this work represents the first transcriptomic analysis of the WCBV interaction in the central nervous system with an accidental host.

Epidemiological characteristics and surveillance of animal bite injuries, in Kerman city, Iran

BACKGROUND

Animal bites are a major threat to human health. The present study was designed to determine the incidence and epidemiological factors and to investigate the process of referral and treatment of animal bite cases in Kerman city.

MATERIALS AND METHODS

This was a cross-sectional (descriptive-analytical) study. All the cases of animal bites that were referred to rabies treatment and prevention centers under the coverage of Kerman health center during 2019 and 2021 were investigated. The data were collected from the health center of Kerman city in Excel form that was registered in the portal of the Ministry of Health. The Chi-square test and Fisher's exact test were used in SPSS24 software to analyze the data.

RESULTS

In this study, 5407 people (4076 men and 1331 women) were bitten by animals. The average incidence of animal bites was 313 per hundred thousand people. The mean ± SD age of the injured was 31.38 ± 17.72 years. 73.2% of cases of attacking animals were dogs, and half of those dogs had owners. 58.6% of cases were injured in the hand, and 94.2% referred to rabies treatment and prevention centers in the first 48 h after the bite. No cases of animal-bitten deaths were reported during this period. Between gender (P = 0.006), age (P = 0.013), place of residence (P = 0.003), occupation (P < 0.000), history of previous bites and vaccinations (P = 0.001), and injured limb (P < 0.000) and not going to receive the next round of vaccinations, there was a statistically significant correlation.

CONCLUSION

Animal bites are a major health problem in Kerman, and due to creating health problems and economic losses, it is necessary to take serious action to control and prevent this health threat.

Adaptive Evolution of the OAS Gene Family Provides New Insights into the Antiviral Ability of Laurasiatherian Mammals

Many mammals risk damage from virus invasion due to frequent environmental changes. The oligoadenylate synthesis (OAS) gene family, which is an important component of the immune system, provides an essential response to the antiviral activities of interferons by regulating immune signal pathways. However, little is known about the evolutionary characteristics of OASs in Laurasiatherian mammals. Here, we examined the evolution of the OAS genes in 64 mammals to explore the accompanying molecular mechanisms of the antiviral ability of Laurasiatherian mammals living in different environments. We found that OAS2 and OAS3 were found to be pseudogenes in Odontoceti species. This may be related to the fact that they live in water. Some Antilopinae, Caprinae, and Cervidae species lacked the OASL gene, which may be related to their habitats being at higher altitudes. The OASs had a high number of positive selection sites in Cetartiodactyla, which drove the expression of strong antiviral ability. The OAS gene family evolved in Laurasiatherian mammals at different rates and was highly correlated with the species' antiviral ability. The gene evolution rate in Cetartiodactyla was significantly higher than that in the other orders. Compared to other species of the Carnivora family, the higher selection pressure on the OAS gene and the absence of positive selection sites in Canidae may be responsible for its weak resistance to rabies virus. The OAS gene family was relatively conserved during evolution. Conserved genes are able to provide better maintenance of gene function. The rate of gene evolution and the number of positively selected sites combine to influence the resistance of a species to viruses. The positive selection sites demonstrate the adaptive evolution of the OAS gene family to the environment. Adaptive evolution combined with conserved gene function improves resistance to viruses. Our findings offer insights into the molecular and functional evolution of the antiviral ability of Laurasian mammals.

Alkaloids as potential antivirals. A comprehensive review

Alkaloids are a diverse group of natural phytochemicals. These phytochemicals in plants provide them protection against pests, and herbivorous organisms and also control their development. Numerous of these alkaloids have a variety of biological effects, and some have even been developed into medications with different medicinal properties. This review aims to provide a broad overview of the numerous naturally occurring alkaloids (isolated from both terrestrial and aquatic species) along with synthetically produced alkaloid compounds having prominent antiviral properties. Previous reviews on this subject have focused on the biological actions of both natural and synthetic alkaloids, but they have not gone into comprehensive detail about their antiviral properties. We reviewed here several antiviral alkaloids that have been described in the literature in different investigational environments i.e. (in-vivo, in-ovo, in-vitro, and in-silico), and found that these alkaloid compounds have significant antiviral properties against several infectious viruses. These alkaloids repressed and targeted various important stages of viral infection at non-toxic doses while some of the alkaloids reported here also exhibited comparable inhibitory activities to commercially used drugs. Overall, these anti-viral effects of alkaloids point to a high degree of specificity, implying that they could serve as effective and safe antiviral medicines if further pursued in medicinal and pharmacological investigations.