Serosurvey of rabies virus, canine distemper virus, parvovirus, and influenza virus in military working dogs in Korea

Over-expression of IL-33 enhances rabies virus early antigen presentations and cellular immune responses in mice

Human inactivated rabies virus (RABV) vaccines have been widely used worldwide over 30 years. The mechanisms of humoral immunity elicited by previously reported rabies candidate vaccines have been fully investigated, but little is known about the cellular immunity profiles. Herein, the recombinant RABV rLBNSE-IL-33 overexpressing the mouse interleukin-33 (IL-33) proliferated well in Neuro-2a cells and had no effects with the parent virus on growth kinetic in vitro and viral pathogenicity in mice. The rLBNSE-IL-33 experienced more antigen presentations by MHC-II on DCs and activated more CD4+ T cells which helped recruit more CD19+CD40+ B cells in blood and promote rapid and robust IgG1 antibodies responses at initial infection stage compared with the parent rLBNSE strain. Simultaneously, the rLBNSE-IL-33 were also presented by MHC-I to CD8+ T cells which contributed to produce high levels of IgG2a. The rLBNSE-IL-33 elicited significantly high levels of RABV-specific IFN-γ secreting memory CD4+ T cells, more RABV-specific IL-4 and IFN-γ secreting memory CD8+ T cells in spleens at early infection stage in mice. Altogether, overexpression of IL-33 in rLBNSE-IL-33 enhanced early antigen presentation, markedly promote CD4+, memory CD4+ and CD8+ T cells-mediated responses and provided a 100 % protection from lethal RABV challenge in mice. These findings provided an alternative novel therapy and vaccine strategy in future.

Prevalence of Serum Antibody Titers against Core Vaccine Antigens in Italian Dogs

Canine vaccination is the main tool for preventing dangerous and widespread diseases. The strongly recommended (core) dog vaccines are against Canine Parvovirus type 2 (CPV-2), Canine Distemper Virus (CDV), and Canine Adenovirus (CAdV-1), but vaccination protocols should be tailored to dog lifestyles. Vaccination guidelines suggest vaccinating adult dogs no more frequently than every 3 years using modified live (attenuated) vaccines (MLV), thus obtaining a long-lasting (sometimes throughout life) specific protection in many but not all animals. The aim of this study was to determine the actual levels of seroprotection against CPV-2, CDV and CAdV-1 in a cohort of Italian dogs by using the in-practice test VacciCheck. A total of 1,027 dogs (951 vaccinated and 76 unvaccinated) were analyzed for Protective Antibody Titers (PATs) against CPV-2, CDV, and CAdV-1. Differences related to sex, age, breed size, health status, and time elapsed since last vaccination were evaluated. Half of the entire canine cohort (50.6%) had PATs for all three viruses (68.5% considering only vaccinated dogs). In particular, 90.8% of dogs were protected against CPV-2, 68.6% against CDV, and 79.8% against CAdV-1. Most dogs remained protected for 3 years after vaccination or longer. Revaccination on a 3-year basis can then be recommended for core MLV vaccines without altering individual's seroprotection or even herd immunity.

Long-term humoral immunogenicity, safety and protective efficacy of inactivated vaccine against reindeer rabies

The core element of the reindeer rabies eradication strategy is regular application of vaccines to obtain and uphold a vaccination coverage sufficient for the ceasing of rabies virus transmission. This article presents the results of reindeer humoral immunity intensity and duration study after the immunization with two form of inactivated rabies vaccines (adjuvanted liquid vaccine and non-adjuvanted lyophilized vaccine) based on the Shchelkovo-51 rabies virus strain. Efficiency of post-vaccine immunity was assessed by measuring the animal blood serum virus-neutralizing antibody level in a neutralization test. The study determined the efficient rabies vaccine injection dose as equal to 3 ml. A single dose of 3 ml of these vaccines induced stable production of specific neutralizing antibodies in reindeer as early as 7 day after administration, and by 30 days after immunization, it significantly exceeded the minimal threshold level accepted by OIE. Two doses of vaccines administration with an interval of 30 days are required to achieve a strong immunity with the rabies-specific virus-neutralizing antibody titer of more than 0.5 IU/ml for at least 2 years. Our data do not support the benefit of an adjuvanted vaccine for the prevention of rabies in reindeer.

A recombinant rabies virus expressing Echinococcus granulosus EG95 induces protective immunity in mice

Cystic echinococcosis (CE), caused by Echinococcus granulosus (E, is a zoonosis with a worldwide distribution, resulting in heavy impact to public health and social economics. In this study, we generated a recombinant rabies virus (RABV) expressing EG95 protein of E. granulosus (LBNSE-EG95) as a bivalent candidate vaccine for use in sheep and cattle against CE and rabies, which is another severe health threat in CE-endemic areas. It was found that EG95 was successfully expressed without altering the pathogenicity of parent LBNSE vector. Further study showed that LBNSE-EG95 immunization in mice elicited activation of dendric cells (DCs) and B cells and induced Th1-/Th2-mediated cellular immune responses, leading to robust production of RABV neutralizing antibodies and high level of EG95-sepecific antibodies with more than 90% protection against CE. In addition, single dose of LBNSE-EG95 conferred full protection against lethal RABV challenge in mice. Collectively, these results suggest that the recombinant LBNSE-EG95 has the potential to be developed as an efficient bivalent vaccine for sheep and cattle use in endemic areas of CE and rabies.

The first study on confirmation and risk factors of acute and chronic canine distemper in stray dogs in Wasit Province, Iraq, using enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction

Background and Aim:

In Iraq, stray dogs represent a critical population of free-roaming animals, which probably play a role in the transmission of different infections to other animals. Canine distemper is one of the most growing viral threats to carnivores in many countries worldwide, including Iraq. Therefore, this study was aimed to diagnose the disease using serological and molecular assay and the role of risk factors in the spreading infection.

Materials and Methods:

In all, 158 venous blood samples were collected randomly from stray dogs in rural and sub-urban areas of Iraq from May 2019 to December 2020. The samples were examined serologically using two enzyme-linked immunosorbent assay (ELISA) kits, immunoglobulin G (IgG) and immunoglobulin M (IgM), and molecularly by reverse transcription-polymerase chain reaction (RT-PCR) to detect and confirm chronic and acute infections. To determine the association between infection and various risk factors, the study animals were divided according to their locations, sexes, and ages. The age groups were ≤8 months (puppy), 1-3 years (young), and ≥3 years (old/mature).

Results:

ELISA result shows that 6.96% and 19.62% of dogs were seropositive for acute and chronic distemper, respectively. The titer of chronic infections (0.421±0.027) was significantly higher (p≤0.025) than that of acute canine distemper (0.337±0.016). On RT-PCR, 8.86% of dogs were found positive for distemper. Using RT-PCR as the gold standard, the sensitivity and specificity of the IgM ELISA kit were 75% and 98.63%, respectively, whereas the positive and negative predictivity were 81.82% and 97.96%, respectively. A significant variation (p<0.05) was observed in the distribution of positive findings among the different epidemiological risk factors. Compared with rural areas, positivity was significantly higher (p<0.05) in sub-urban areas on IgM (26.92%) and IgG (64.15%) ELISA and RT-PCR (34.62%). On IgM ELISA and RT-PCR, no significant differences (p>0.05) were found among the three age groups; however, positivity was significantly higher (p≤0.048) in the ≥3 years group (22.73%) on IgG ELISA. Furthermore, only IgG ELISA showed a significantly higher (p≤0.032) positivity rate in female dogs (25.23%) than in male dogs (7.84%).

Conclusion:

To the best of our knowledge, this is the first Iraqi study to demonstrate acute and chronic canine distemper in stray dogs, suggesting that the prolonged shedding of virus from positive dogs is a critical point in the epidemiology of the disease. Additional studies in dogs or other carnivores are required to establish baseline data on the prevalence of the disease in Iraq.

Investigation of protective level of rabies antibodies in vaccinated dogs in Chennai, India

BACKGROUND

Rabies is still endemic in India causing an estimated 20,000 human deaths a year. Free roaming dogs and unvaccinated owned dogs play a major role in the maintenance of the disease. Dog vaccination is the most crucial aspect of rabies prevention and control strategies; therefore vaccine immunogenicity and longevity are important determinants of the efficiency of rabies control efforts.

METHODS

In this study at Madras Veterinary College, India, a total of 297 serum samples were collected from owned dogs that were vaccinated against rabies. Data regarding age, gender, breed, neuter status and last date of vaccination were collected at the time of blood collection. The level of rabies virus neutralising antibodies in the sera of these dogs was measured through rapid focus fluorescence inhibition test. The factors associated with protective level of rabies antibodies in vaccinated dogs were investigated through multivariable regression analysis.

RESULTS

This cross-sectional investigation shows that only 40% (119/297) of the all the dogs in the study showed presence of protective level of anti-rabies antibodies, and 40% (72/180) of the dogs vaccinated within the last year showed presence of protective levels of antibodies causing concern about rabies vaccine quality and its impact on rabies control. The study also shows that older and neutered dogs are more likely to have protective titre among vaccinated dogs, while non-descript breed dogs are less likely to have a protective titre compared to pure breeds.

CONCLUSION

In this study 60% (108/180) of young prima dogs and adult dogs did not show protective levels of antibodies within the year of last rabies vaccination, although they had previous vaccination history. This high percentage of apparent non-responders is a cause of concern of administration, distribution, storage, potency and quality management of vaccines in India.

Inherent Serum Inhibition of Influenza Virus Neuraminidases

Influenza virus vaccines have been designed for human and veterinary medicine. The development for broadly protective influenza virus vaccines has propelled the vaccine field to investigate and include neuraminidase (NA) components into new vaccine formulations. The antibody-mediated protection induced by NA vaccines is quantified by inhibition of sialic acid cleavage. Non-immune inhibitors against influenza viruses naturally occur in varying proportions in sera from different species. In this brief report, the inherent ability of raw animal sera to inhibit a panel of influenza virus NA was determined. Raw sera from the same species inhibited more than 50% of influenza viruses tested from four different subtypes, but the breadth of inhibiting NA activity depended on the source of sera. Furthermore, different influenza viruses were inhibited by different sources of sera. Overall, additional studies are needed to ensure that scientific methods are consistent across studies in order to compare NA inhibition results. Through future investigation into the differences between sera from different animal species and how they influence NA inhibition assays, there can be effective development of a broadly protective influenza virus vaccines for veterinary and human use.

Preventive Health Care for Working Dogs

The goal of preventive care is to maintain and optimize health by averting preventable problems. Effective preventive care programs for working dogs must incorporate standard procedures applicable to dogs in general with additional elements pertinent to the more specific characteristics of breed, geographic location, living and working conditions, and physical and mental tasks required of the working dog. This article covers the basic essential preventive health guidelines for all working dogs as well as the specific breed, occupational, and regional considerations to be taken into account.

Genetically modified rabies virus vector-based bovine ephemeral fever virus vaccine induces protective immune responses against BEFV and RABV in mice

Bovine ephemeral fever (BEF), caused by the bovine ephemeral fever virus (BEFV), is associated with an acute febrile infection in cattle and widespread in tropical and subtropical areas, leading to great economic losses to cattle and milk industry. However, no efficacious BEF vaccine is currently available in China. Herein, we generated a recombinant rabies virus (RABV) expressing BEFV glycoprotein (LBNSE-BG), utilizing a reverse genetics system based on the recombinant rabies virus strain LBNSE. It was found that mice immunized with LBNSE-BG produced robust neutralizing antibodies against both BEFV and RABV, and developed complete protection from lethal RABV challenge. Further studies showed that LBNSE-BG activated more dendritic cells (DCs), B cells and T cells in immunized mice than the parent virus LBNSE. Collectively, these findings demonstrate that the recombinant LBNSE-BG described here has the potential to be developed as a cost-effective and efficacious bivalent vaccine for cattle use in endemic areas of BEF and rabies.

Recombinant Human Adenovirus Type 5 Co-expressing RABV G and SFTSV Gn Induces Protective Immunity Against Rabies Virus and Severe Fever With Thrombocytopenia Syndrome Virus in Mice

Both severe fever with thrombocytopenia syndrome (SFTS) and rabies are severe zoonotic diseases. As co-hosts of rabies virus (RABV) and SFTS virus (SFTSV), dogs and cats could not only be infected but also transmit the virus to human. Hence, developing a bivalent vaccine against both SFTS and rabies is urgently needed. In this study, we generated a recombinant replication-deficient human adenovirus type 5 (Ad5) co-expressing RABV G and SFTSV Gn (Ad5-G-Gn) and evaluated its immunogenicity and efficacy in mice. Ad5-G-Gn immunization activated more dendritic cells (DCs) and B cells in lymph nodes (LNs) and induced Th1-/Th2-mediated responses in splenocytes, leading to robust production of neutralizing antibodies against SFTSV and RABV. In addition, single dose of Ad5-G-Gn conferred mice complete protection against lethal RABV challenge and significantly reduced splenic SFTS viral load. Therefore, our data support further development of Ad5-G-Gn as a potential bivalent vaccine candidate against SFTS and rabies for dog and cat use.

Molecular and serological surveys of canine distemper virus: A meta-analysis of cross-sectional studies

BACKGROUND

Canine morbillivirus (canine distemper virus, CDV) persists as a serious threat to the health of domestic dogs and wildlife. Although studies have been conducted on the frequency and risk factors associated with CDV infection, there are no comprehensive data on the current epidemiological magnitude in the domestic dog population at regional and national levels. Therefore, we conducted a cross-sectional study and included our results in a meta-analysis to summarize and combine available data on the frequency and potential risk factors associated with CDV infection.

METHODS

For the cross-sectional study, biological samples from dogs suspected to have canine distemper (CD) were collected and screened for viral RNA. Briefly, the PRISMA protocol was used for the meta-analysis, and data analyses were performed using STATA IC 13.1 software.

RESULTS

CDV RNA was detected in 34% (48/141) of dogs suspected to have CD. Following our meta-analysis, 53 studies were selected for a total of 11,527 dogs. Overall, the pooled frequency of CDV positivity based on molecular and serological results were 33% (95% CI: 23-43) and 46% (95% CI: 36-57), respectively. The pooled subgroup analyses of clinical signs, types of biological samples, diagnostic methods and dog lifestyle had a wide range of CDV positivity (range 8-75%). Free-ranging dogs (OR: 1.44, 95% CI: 1.05-1.97), dogs >24 months old (OR: 1.83, 95% CI: 1.1-3) and unvaccinated dogs (OR: 2.92, 95% CI: 1.26-6.77) were found to be positively associated with CDV infection. In contrast, dogs <12 months old (OR: 0.36, 95% CI: 0.20-0.64) and dogs with a complete anti-CDV vaccination (OR: 0.18, 95% CI: 0.05-0.59) had a negative association.

CONCLUSION

Considering the high frequency of CDV positivity associated with almost all the variables analyzed in dogs, it is necessary to immediately and continuously plan mitigation strategies to reduce the CDV prevalence, especially in determined endemic localities.