Pathogenicity of novel hantavirus isolate and antigenicity and immunogenicity of novel strain-based inactivated vaccine

BACKGROUND

Hantaan virus (HTNV, Orthohantavirus hantanensae species, Hantaviridae family) is the main etiological agent responsible for hemorrhagic fever with renal syndrome (HFRS). The novel HTNV may pose a potential danger to the control and prevention of HFRS in China, which highlights the importance of vaccine development in public health management. In previous studies, our laboratory discovered and successfully isolated a new HTNV strain, HV004 strain, from Apodemus agrarius captured in an epidemic area in Hubei, China.

METHODS

An initial biological and pathogenicity characterization of HTNV 76-118 (standard train), HV114 strain (a clinical isolate from Hubei province in 1986), and the novel isolate HV004 strain from the epidemic areas of Hubei province were performed in susceptible cells and in vivo. An experimental HV004 strain inactivated vaccine was prepared, and its corresponding immunogenicity was analyzed in BALB/c mice.

RESULTS

HV004 strain had a similar but higher pathogenicity than HTNV 76-118 and HV114 in suckling mice. A subcutaneous vaccination (s.c.) with the inactivated HTNV vaccine adjuvanted with aluminum, followed by a challenge intraperitoneally with 106 FFU/ml HTNV, afforded full protection against an HTNV challenge. All immunized mice in every group elicited serum neutralizing antibodies with increasing dosages, which may protect mice from HTNV infection. A dose-dependent stimulation index of splenocytes was also observed in immunized mice. The percentage of IFN-γ-producing CD3+CD8+ T cells was significantly higher in the spleens of immunized mice than in those of control mice.

CONCLUSIONS

These findings suggest that the inactivated HTNV vaccine may stimulate mice to produce high levels of antibodies with neutralization activity and elicit specific anti-HTNV humoral and cellular immune responses in BALB/c mice against the prevalent strain of HTNV in south central China.

Investigation of a subunit protein vaccine for HFRS based on a consensus sequence between envelope glycoproteins of HTNV and SEOV

Due to the global resurgence of hemorrhagic fever with renal syndrome (HFRS), more attention is being focused on this dangerous illness. In China and Korea, the only vaccines available are the virus-inactivated vaccine against Hantaan virus (HTNV) or Seoul virus (SEOV), but their efficacy and safety are inadequate. Therefore, it is important to develop new vaccines that are safer and more efficient to neutralize and regulate areas with a high prevalence of HFRS. We employed bioinformatics methods to design a recombinant protein vaccine based on conserved regions of protein consensus sequences in HTNV and SEOV membranes. The S2 Drosophila expression system was utilized to enhance protein expression, solubility and immunogenicity. After the Gn and Gc proteins of HTNV and SEOV were successfully expressed, mice were immunized, and the humoral immunity, cellular immunity, and in vivo protection of the HFRS universal subunit vaccine were systematically evaluated in mouse models. These results indicated that the HFRS subunit vaccine generated elevated levels of binding and neutralizing antibodies, particularly IgG1, compared to that of the traditional inactivated HFRS vaccine. Additionally, the spleen cells of immunized mice secreted IFN-r and IL-4 cytokines effectively. Moreover, the HTNV-Gc protein vaccine successfully protected suckling mice from HTNV infection and stimulated GC responses. In this research, a new scientific approach is investigated to develop a universal HFRS subunit protein vaccine that is capable of producing effective humoral and cellular immunity in mice. The results suggest that this vaccine could be a promising candidate for preventing HFRS in humans.

Hemorrhagic Fever with Renal Syndrome in Asia: History, Pathogenesis, Diagnosis, Treatment, and Prevention

Hemorrhagic Fever with Renal Syndrome (HFRS) is the most frequently diagnosed zoonosis in Asia. This zoonotic infection is the result of exposure to the virus-contaminated aerosols. Orthohantavirus infection may cause Hemorrhagic Fever with Renal Syndrome (HRFS), a disease that is characterized by acute kidney injury and increased vascular permeability. Several species of orthohantaviruses were identified as causing infection, where Hantaan, Puumala, and Seoul viruses are most common. Orthohantaviruses are endemic to several Asian countries, such as China, South Korea, and Japan. Along with those countries, HFRS tops the list of zoonotic infections in the Far Eastern Federal District of Russia. Recently, orthohantavirus circulation was demonstrated in small mammals in Thailand and India, where orthohantavirus was not believed to be endemic. In this review, we summarized the current data on orthohantaviruses in Asia. We gave the synopsis of the history and diversity of orthohantaviruses in Asia. We also described the clinical presentation and current understanding of the pathogenesis of orthohantavirus infection. Additionally, conventional and novel approaches for preventing and treating orthohantavirus infection are discussed.

Spatiotemporal association of rapid urbanization and water-body distribution on hemorrhagic fever with renal syndrome: A case study in the city of Xi'an, China

Hemorrhagic fever with renal syndrome (HFRS) is a zoonosis characterized by clinical features of high fever, hemorrhage, and renal damage. China has the largest number of HFRS cases worldwide, accounting for over 90% of the total reported cases. In this paper, we used surveyed HFRS data and satellite imagery to conduct geostatistical analysis for investigating the associations of rapid urbanization, water bodies, and other factors on the spatiotemporal dynamics of HFRS from year 2005 to 2018 in Xi'an City, Northwest China. The results revealed an evident epidemic aggregation in the incidence of HFRS within Xi'an City with a phenomenal fluctuation in periodic time series. Rapid urbanization was found to greatly affect the HFRS incidence in two different time phases. HFRS caused by urbanization influences farmers to a lesser extent than it does to non-farmers. The association of water bodies with the HFRS incidence rate was found to be higher within the radii of 696.15 m and 1575.39 m, which represented significant thresholds. The results also showed that geomatics approaches can be used for spatiotemporally investigating the HFRS dynamic characteristics and supporting effective allocations of resources to formulate strategies for preventing epidemics.

Effects and interaction of meteorological factors on hemorrhagic fever with renal syndrome incidence in Huludao City, northeastern China, 2007-2018

Background

Hemorrhagic fever with renal syndrome (HFRS), a rodent-borne disease, is a severe public health threat. Previous studies have discovered the influence of meteorological factors on HFRS incidence, while few studies have concentrated on the stratified analysis of delayed effects and interaction effects of meteorological factors on HFRS.

Objective

Huludao City is a representative area in north China that suffers from HFRS with primary transmission by Rattus norvegicus. This study aimed to evaluate the climate factors of lag, interaction, and stratified effects of meteorological factors on HFRS incidence in Huludao City.

Methods

Our researchers collected meteorological data and epidemiological data of HFRS cases in Huludao City during 2007–2018. First, a distributed lag nonlinear model (DLNM) for a maximum lag of 16 weeks was developed to assess the respective lag effect of temperature, precipitation, and humidity on HFRS incidence. We then constructed a generalized additive model (GAM) to explore the interaction effect between temperature and the other two meteorological factors on HFRS incidence and the stratified effect of meteorological factors.

Results

During the study period, 2751 cases of HFRS were reported in Huludao City. The incidence of HFRS showed a seasonal trend and peak times from February to May. Using the median WAT, median WTP, and median WARH as the reference, the results of DLNM showed that extremely high temperature (97.5^th percentile of WAT) had significant associations with HFRS at lag week 15 (RR = 1.68, 95% CI: 1.04–2.74) and lag week 16 (RR = 2.80, 95% CI: 1.31–5.95). Under the extremely low temperature (2.5^th percentile of WAT), the RRs of HFRS infection were significant at lag week 5 (RR = 1.28, 95% CI: 1.01–1.67) and lag 6 weeks (RR = 1.24, 95% CI: 1.01–1.57). The RRs of relative humidity were statistically significant at lag week 10 (RR = 1.19, 95% CI: 1.00–1.43) and lag week 11 (RR = 1.24, 95% CI: 1.02–1.50) under extremely high relative humidity (97.5^th percentile of WARH); however, no statistically significance was observed under extremely low relative humidity (2.5^th percentile of WARH). The RRs were significantly high when WAT was -10 degrees Celsius (RR = 1.34, 95% CI: 1.02–1.76), -9 degrees Celsius (1.37, 95% CI: 1.04–1.79), and -8 degrees Celsius (RR = 1.34, 95% CI: 1.03–1.75) at lag week 5 and more than 23 degrees Celsius after 15 weeks. Interaction and stratified analyses showed that the risk of HFRS infection reached its highest when both temperature and precipitation were at a high level.

Conclusions

Our study indicates that meteorological factors, including temperature and humidity, have delayed effects on the occurrence of HFRS in the study area, and the effect of temperature can be modified by humidity and precipitation. Public health professionals should pay more attention to HFRS control when the weather conditions of high temperature with more substantial precipitation and 15 weeks after the temperature is higher than 23 degrees Celsius.

Climate change impacts vector-borne disease incidence by influencing vectors’ habitat and behaviors. As a rodent-borne disease, HFRS’s incidence rate fluctuates with the change of meteorological factors. In this study, we model the meteorological factors and time-series cases to explore the exposure-lag-response effect and interaction between meteorological factors on the risk of HFRS, respectively. The result showed there exist a lag effect between meteorological factors and the occurrence of HFRS and we find that a temperature higher than 23 Celsius degrees resulted in a significantly higher HFRS incidence after 15 weeks; a relative humidity higher than 93% led to a significantly higher incidence after 10 weeks. Also, a synergistic interaction between high temperature and high precipitation on HFRS risk was detected, this effect can be attributed to increased animal reproduction and food resources under this environment. This study provides a basis for in-depth evaluating the impact of meteorological factors and their interaction on HFRS.

Intrinsic and extrinsic drivers of transmission dynamics of hemorrhagic fever with renal syndrome caused by Seoul hantavirus

Seoul hantavirus (SEOV) has recently raised concern by causing geographic range expansion of hemorrhagic fever with renal syndrome (HFRS). SEOV infections in humans are significantly underestimated worldwide and epidemic dynamics of SEOV-related HFRS are poorly understood because of a lack of field data and empirically validated models. Here, we use mathematical models to examine both intrinsic and extrinsic drivers of disease transmission from animal (the Norway rat) to humans in a SEOV-endemic area in China. We found that rat eradication schemes and vaccination campaigns, but below the local elimination threshold, could diminish the amplitude of the HFRS epidemic but did not modify its seasonality. Models demonstrate population dynamics of the rodent host were insensitive to climate variations in urban settings, while relative humidity had a negative effect on the seasonality in transmission. Our study contributes to a better understanding of the epidemiology of SEOV-related HFRS, demonstrates asynchronies between rodent population dynamics and transmission rate, and identifies potential drivers of the SEOV seasonality.

Seoul hantavirus (SEOV) infections are common in Europe and Asia where a considerably high seroprevalence among the population is found. However, only relatively few hemorrhagic fever with renal syndrome (HFRS) cases are reported. Comprehensive epidemiological data is necessary to study the patterns and drivers of this underestimated disease. Here, we analyzed rodent host surveillance and seroprevalence data from 1998 to 2015 for disease outbreaks in Huludao City, one of the typical SEOV-endemic areas for HFRS in China. Our mathematical models quantified the drivers on HFRS transmission and estimated the epidemiological parameters. Our study provides an understanding of its ecological process between intrinsic and extrinsic factors, human-rodent interface and disease dynamics.

REVIEW OF EPIDEMIOLOGIC SITUATION ON HEMORRHAGIC FEVER WITH RENAL SYNDROME (HERS) IN RUSSIAN FEDERATION IN 1990 - 2015

AIM

Analyze HFRS morbidity in Russian Federation during the last 25 years (1990 - 2015).

MATERIALS AND METHODS

Official statistics of Federal Service for Surveillance on Consumers' Rights Protection and Human Weillbeing (CPS), including Federal Centre of Hygiene and Epidemiology, were used for the analysis, as well as materials from regional departments of CPS and centers of hygiene and epidemiology. Epidemiologic analysis was the main method. Statistical treatment of the results obtained was carried out using gener- ally accepted methods of variation statistics with elements of system analysis. Results; For the studied period (1990 - 2015) 194 116 cases of HFRS were registered. Morbidity was registered in 8 federal districts of the Russian Federation in 58 subjects. The most intense epidemiologic situation was noted in Privolzhsky Federal District, that accounted for 86.4% of total HFRS morbidity during the -studied period. Analysis of morbidity was carried out in every federal district, most epidemically unfavorable territories are shown.

CONCLUSION

The data presented on HFRS morbidity reflect -unfavorable situation for this disease in Russian Federation. Measures to prevent the emergence of diseases to reduce the general level of morbidity in Russian Federation are presented.

Construction of a Seasonal Difference-Geographically and Temporally Weighted Regression (SD-GTWR) Model and Comparative Analysis with GWR-Based Models for Hemorrhagic Fever with Renal Syndrome (HFRS) in Hubei Province (China)

Hemorrhagic fever with renal syndrome (HFRS) is considered a globally distributed infectious disease which results in many deaths annually in Hubei Province, China. In order to conduct a better analysis and accurately predict HFRS incidence in Hubei Province, a new model named Seasonal Difference-Geographically and Temporally Weighted Regression (SD-GTWR) was constructed. The SD-GTWR model, which integrates the analysis and relationship of seasonal difference, spatial and temporal characteristics of HFRS (HFRS was characterized by spatiotemporal heterogeneity and it is seasonally distributed), was designed to illustrate the latent relationships between the spatio-temporal pattern of the HFRS epidemic and its influencing factors. Experiments from the study demonstrated that SD-GTWR model is superior to traditional models such as GWR- based models in terms of the efficiency and the ability of providing influencing factor analysis.

Beech Fructification and Bank Vole Population Dynamics--Combined Analyses of Promoters of Human Puumala Virus Infections in Germany

The transmission of wildlife zoonoses to humans depends, amongst others, on complex interactions of host population ecology and pathogen dynamics within host populations. In Europe, the Puumala virus (PUUV) causes nephropathia epidemica in humans. In this study we investigated complex interrelations within the epidemic system of PUUV and its rodent host, the bank vole (Myodes glareolus). We suggest that beech fructification and bank vole abundance are both decisive factors affecting human PUUV infections. While rodent host dynamics are expected to be directly linked to human PUUV infections, beech fructification is a rather indirect predictor by serving as food source for PUUV rodent hosts. Furthermore, we examined the dependence of bank vole abundance on beech fructification. We analysed a 12-year (2001-2012) time series of the parameters: beech fructification (as food resource for the PUUV host), bank vole abundance and human incidences from 7 Federal States of Germany. For the first time, we could show the direct interrelation between these three parameters involved in human PUUV epidemics and we were able to demonstrate on a large scale that human PUUV infections are highly correlated with bank vole abundance in the present year, as well as beech fructification in the previous year. By using beech fructification and bank vole abundance as predictors in one model we significantly improved the degree of explanation of human PUUV incidence. Federal State was included as random factor because human PUUV incidence varies considerably among states. Surprisingly, the effect of rodent abundance on human PUUV infections is less strong compared to the indirect effect of beech fructification. Our findings are useful to facilitate the development of predictive models for host population dynamics and the related PUUV infection risk for humans and can be used for plant protection and human health protection purposes.

A multi-head intradermal electroporation device allows for tailored and increased dose DNA vaccine delivery to the skin

The identification of an effective and tolerable delivery method is a necessity for the success of DNA vaccines in the clinic. This manuscript describes the development and validation of a multi-headed intradermal electroporation device which would be applicable for delivering multiple DNA vaccine plasmids simultaneously but spatially separated. Reporter gene plasmids expressing green and red fluorescent proteins were used to demonstrate the impact of spatial separation on DNA delivery to increase the number of transfected cells and avoid interference through visible expression patterns. To investigate the impact of plasmid interference on immunogenicity, a disease target was investigated where issues with multi-valent vaccines had been previously described. DNA-based Hantaan and Puumala virus vaccines were delivered separately or as a combination and the effect of multi-valence was determined by appropriate assays. While a negative impact was observed for both antigenic vaccines when delivered together, these effects were mitigated when the vaccine was delivered using the multi-head device. We also demonstrate how the multi-head device facilitates higher dose delivery to the skin resulting in improved immune responses. This new multi-head platform device is an efficient, tolerable and non-invasive method to deliver multiple plasmid DNA constructs simultaneously allowing the tailoring of delivery sites for combination vaccines. Additionally, this device would allow the delivery of multi-plasmid vaccine formulations without risk of impacted immune responses through interference. Such a low-cost, easy to use device platform for the delivery of multi-agent DNA vaccines would have direct applications by the military and healthcare sectors for mass vaccination purposes.

[A hantavirus killed an Israeli researcher: hazards while working with wild animals]

An Israeli researcher working in Finland with Bank Voles, contracted an infectious viral disease and died. This was a rare event, but it is important to learn about this class of viruses and to be aware of the hazards while working in the field in close contact with wild animals. The virus termed Puumala belongs to the genus Hanta from the Bunyaviridae family. The natural reservoir is rodents, mice, rats and Bank Votes for the Puuamala strain. The disease is termed HFRS (hemorrhagic fever with renal syndrome), is prevalent in Asia and Europe, affecting 200,000 people a year, with 5-15% percent mortality (although in Finland mortality rate is 0.1%). The New World strains cause HPS (hemorrhagic pulmonary syndrome) affecting 200 people a year with 40% mortality. Virus is present in all rodents excretions, and route of infection is by aerosols, hand to mucus membranes contamination, by rodents bites and by contaminated food or water. More than 226 work related infections were documented. Treatment with Ribavirin helps in HFRS but not in HPS. The virus is stable in the environment for long periods, and research must be carried out at biosafety level 3. Working outdoors in rodent infested area, should be carried out using protective clothing, gloves, googles and face mask whenever aerosol producing tasks are performed. Both indoor and outdoor, it is important to adhere to self-hygienic procedures, especially hand washing.

[Epidemiologic surveillance and prophylaxis of hemorrhagic fever with renal syndrome in Russian Federation]

Hemorrhagic fever with renal syndrome (HFRS) remains an actual natural-focal non-transmissible infection comprising more than 90% in structure of all the hemorrhagic fevers registered on the territory of Russian Federation. On the whole in multiyear dynamics of HFRS morbidity in Russia a pronounced tendency of growth with an average increase of morbidity of 1.7% per year that is caused by both improvement of clinical and laboratory diagnostics and objective increase of morbidity is noted. Currently a regulatory methodical base for organization of epidemiologic surveillance and prophylaxis of HFRS in Russian Federation is created.

[Comparison of direct immune-fluorescent assay and real-time quantitative PCR in detecting the Hantavirus]

OBJECTIVE

To compare the differences between the direct immuno-fluorescent assay (DFA) and real-time quantitative PCR in detecting the Hantavirus (HV) in rat lungs.

METHODS

From April to October in 2012, a total of 479 rats were caught by mouse-trap in residential or wild areas in Huxian, Jingyang, and Meixian of Shaanxi province, where haemorrhagic fever with renal syndrome (HFRS) was highly prevalent. The rats were dissected to take the two lungs, one was frozen and applied immuno-fluorescent assay to detect HV antigen while the other one was extracted its RNA and detected HV nucleic acid by real-time quantitative PCR. Then we compared the positive rate of the two methods.

RESULTS

Out of the 479 rats, 105 were caught from residential areas and the other 374 were caught from wild areas. Among the 105 rats caught from residential areas, no HV were detected out neither by DFA nor by real-time quantitative PCR. Among the 374 wild rats, 13.1% (49/374) were detected HV positive by DFA and 14.7% (55/374) were detected HV positive by real-time quantitative PCR. The difference showed no statistical significance (χ(2) = 0.402, P = 0.526). When detecting each lung sample, the HV positive rate was 10.2% (49/479) under the detection by DFA while the HV positive rate was 11.5% (55/479) under the detection by real-time quantitative PCR. The difference had no statistical significance (χ(2) = 1.286, P = 0.257) and the consistency coefficient was 68.2% under the paired chi-square test analysis, which showed high consistency (u = 11.759, P < 0.05). The sensitivity of real-time quantitative PCR to detect HV was 77.6% (38/49) comparing with DFA as standard, and the specificity was 96.1% (413/430). Out of the 9 suspected HV positive sample detected by DFA, 6 were confirmed positive by real-time quantitative PCR and 3 were denied.

CONCLUSION

Compared with the DFA, real-time quantitative PCR could also be used to detect the infection of HV in rats, and the result might be more stable.

[Actual problems of hemorrhagic fever with renal syndrome]

From 2000 to 2011 85 600 cases of hemorrhagic fever with renal syndrome (HFRS) were registered in Russian Federation. Epidemically active foci of HFRS infection are located generally in temperate latitudes of the European part and the Far East. In the Far East regions whose fraction of all the HFRS disease cases in Russia is around 2%, the causative agents of the infection are Hantaan, Amur, Seoul hantaviruses, the natural reservoir for those are striped field mouse, Korean field mouse and brown rat. In the European part of Russia the causative agent of the infection are Puumala hantavirus as well as 2 genetic subtypes of Dobrava virus, the main reservoirs of those in the nature are bank vole, striped field mouse and Black Sea field mouse, respectively. 9 strain of Puumala and 10 strains of Dobrava virus were isolated. Based on sequencing of Dobrava virus strains significant differences were detected between Dobrava virus strains isolated from Black Sea field mouse from Sochi and striped field mouse from Lipetsk Region. Cultural inactivated vaccine against HFRS was developed and completed preclinical trials.

[Study on comprehensive monitoring of mouse and effect of hemorrhagic fever with renal syndrome vaccine in high prevalence areas of natural focus infectious disease of Zhejiang province in 1994--2010]

OBJECTIVE

To study the comprehensive monitoring mechanism of mouse and the effect of hemorrhagic fever with renal syndrome (HFRS) vaccine in the high prevalence areas of natural focus infectious disease of Zhejiang province in 1994 - 2010.

METHODS

The night trapping method was used to monitor the population proportion, density and the rate of hantavirus (HV) carriers in mice in Xikou township Longyou county in August and September from 1994 to 2010. The healthy residents in Xikou township aged 16 to 60 years were recruited. The subjects were randomly selected as vaccination group and control group according to age, sex, occupational distribution (10 178 in intervention group and 16 159 in control group). Intervention group was given purified and inactivated vaccine from suckling mouse brain, while the control group received no intervention. The prevention effect was evaluated by protective rate of vaccine.

RESULTS

The mouse population was stable in the sixteen years and the apodemus agrarius was the main type (76.5% (564/737)). The average density of mouse was 4.73% (1170/24 727). The average rate of virus carrier of mouse was 3.87% (41/1033). In 1994 - 1995, the density of mouse was 22.82% (186/815) and the rate of virus carrier was 7.0% (10/143). In 2009 - 2010, the density of mouse decreased to 2.75% (119/4330) and the rate of virus carrier was 5.5% (13/237). The average antibody positive rate of mouse from 2005 to 2010 was 4.8% (35/728) and the rate was 4.4% (6/138), 0.0% (0/113), 11.8% (16/136), 1.0% (1/104), 3.7% (4/109) and 6.3% (8/128) in each year (P < 0.01). The protective rate of HFRS vaccine was 96.2% (1 case in intervention group and 41 cases in control group).

CONCLUSION

The density of mouse decreased significantly in Zhejiang province. The rate of virus carrier of mouse is stable. The vaccine is effective.

[Cardiopulmonary syndrome in hantavirus infection (an overview)]

The article provides an overview of domestic and foreign literature on modern aspects of hantavirus infection. Hemorrhagic fever with renal syndrome and hantavirus cardiopulmonary syndrome have a high epidemiological significance for Russia's Armed Forces and the armies of many foreign countries. Current knowledge of the various manifestations of the disease contribute to the improvement of diagnosis and timely delivery of medical and preventive measures.

[Problems in the organization of epidemiological surveillance of natural focal infections and ways of their solution]

The spread of natural focal infections is determined by a set of interrelated and interdependent populations of warm-blooded animals, arthropods, and microorganisms. Real danger to humans makes their foci be included into environmental risk factors in this or that area.

[Long term epidemiological effects of vaccination on hemorrhagical fever with renal syndrome (HFRS) in Shaanxi provincial HFRS epidemic areas]

OBJECTIVE

To evaluate the protective rate and the variation of HFRS-IgG on hemorrhagical fever with renal syndrome (HFRS) vaccine.

METHODS

Cluster, random sampling and cross-sectional study were used to assess the protective rate of HFRS vaccination. Level of HFRS-IgG was detected with ELISA in epidemic and non-epidemic areas of HFRS.

RESULTS

Curve equation was obtained as Yprotective rate=(0.863+0.283/Xvaccination term)×100% by protective rate with vaccination term. Protective rates showed a reducing trend, 90% after 7-8 years of vaccination, 88% after 10 years, and 94% on average. Absorbance (A) value of HFRS-IgG was 4 times higher in persons with vaccination than those without, in the epidemic area. Higher antibody level could be obtained after primary vaccination, but the level of antibody had a 50% reduction after 5-10 years of vaccination, and a 60% reduction after 10 years of vaccination.

CONCLUSION

HFRS antibody had a 50% reduction after 5-10 years of vaccination. The protective rate of HFRS vaccination had a 90% loss, after 7-8 years of vaccination. Booster dose was necessary after 7 years of vaccination.

Toxic epidermal necrolysis with ocular involvement following vaccination for hemorrhagic fever with renal syndrome

We report a case of toxic epidermal necrolysis with ocular involvement following vaccination for hemorrhagic fever with renal syndrome. A healthy 20-year-old male soldier presented with confluent purpuric and erythematous dusky red macules evolving to flaccid blister and epidermal detachment on the whole body with conjunctival injection. The patient had no antecedent medical or surgical conditions except for two doses of hemorrhagic fever with renal syndrome vaccination. With supportive care, skin lesions were improved. Ophthalmic examinations revealed conjunctival injection with epithelial defects in both eyes. Ocular complications were resolved after amniotic membrane transplantation. Toxic epidermal necrolysis may be considered as a possible complication of hemorrhagic fever with renal syndrome vaccination.

[Study on the integrated monitoring program regarding mouse and main mouse-borne disease in Zhejiang province]

OBJECTIVE

To study the integrated monitoring program regarding mouse and plague, hemorrhagic fever of renal syndrome (HFRS) and leptospirosis.

METHODS

Integrated monitoring plan was used. A designated office coordinated 5 departments' actions within the Zhejiang Provincial Center for Disease Control and Prevention (CDC). Cage-trapping method was conducted to monitor the density of mice from June to October, respectively.

RESULTS

Lishui municipal CDC had finished the integrated monitoring program on mouse and mouse-borne disease while the Longyou CDC had finished the field investigation, using the integrated monitoring program. Specimens were sent to provincial CDC. The integrated monitoring program needed more number of personnel and better coordination.Lishui reported 3 leptospirosis cases and 58 HFRS cases in 2009, with the incidence rates as 0.13 and 2.44 per 100 000, respectively. Longyou reported 2 leptospirosis case and 1 HFRS cases in 2009, with the incidence rates as 0.49 and 0.25 per 100 000, respectively. Lishui and Longyou had no plague case. Lishui caught 91 mice in 2009 and the density was 4.17%. Longyou caught 37 mice in 2009, with the density as 1.18 percent. Most mice caught from Lishui were Apodemus agrarius and the next was Mus musculus. In Longyou the Rattus tanezumi ranked the first, followed by Apodemus agrarius. The positive rate of HFRS antigen in Lishui and Longyou were 10.42% and 4.59% respectively. The positive rate of HFRS antibody in Longyou was 3.70%. The culture positive rate of leptospirosis in mouse renal of Lishui and Longyou were 0 and 0.98% respectively. The culture positive rate of leptospirosis in pig renal, duck renal, frog renal and cattle urine of Longyou was 0. The culture positive rate of leptospirosis in duck blood of Longyou was 80%.

CONCLUSION

The integrated monitoring program on mouse and mouse-borne disease seemed to be feasible and could promote the integrated surveillance and control program on mouse and mouse-borne diseases in China.

[A study on indicator system for early-warning on hemorrhagic fever with renal syndrome epidemic]

OBJECTIVE

To establish an early-warning indicator system on outbreak of hemorrhagic fever with renal syndrome by Delphi method seeking expert advices.

METHODS

Firstly, the literature review and the experts meeting method were used to formulate the initiator frame work and indicators. A two-round consultation was used to filter indicators, discuss the boundary of indicators and determine the weighting coefficient among 25 experts from 14 provinces, municipalities and autonomous regions. The relative weightiless of indicators was determined by the weight coefficients method.

RESULTS

The experts' average length of service in prevention and control of hemorrhagic fever with renal syndrome was (23.80 ± 11.70) years. The positivity coefficients of the two-round experts were 100% and 72%. Kendall's coefficients of the two-round consultation were 0.50 (χ(2)(R) = 148.95, P < 0.01) and 0.54 (χ(2)(R) = 212.63, P < 0.01) and opinions among experts became consistent and the consultation had achieved the need of forecast. Four first-class indicators (host animals, risk population, social environment and case-related indicators) and 14 second-class indicators were filtered to develop the indicators system. The weight coefficients of the first-class indicators were 0.28, 0.23, 0.23 and 0.26.

CONCLUSION

The early-warning index system of hemorrhagic fever with renal syndrome has been established and it could provide a reference for the forest and warning of HFRS outbreak.

Hantavirus infections in humans and animals, China

Hemorrhagic fever with renal syndrome (HFRS) is a serious public health problem in the People's Republic of China. Although 7 sero/genotypes of hantaviruses have been found in rodents, only Hantaan virus (carried by Apodemus agrarius mice) and Seoul virus (carried by Rattus norvegicus rats) reportedly cause disease in humans. During 1950-2007, a total of 1,557,622 cases of HFRS in humans and 46,427 deaths (3%) were reported in China. HFRS has been reported in 29 of 31 provinces in China. After implementation of comprehensive preventive measures, including vaccination, in the past decade in China, incidence of HFRS has dramatically decreased; only 11,248 HFRS cases were reported in 2007. Mortality rates also declined from the highest level of 14.2% in 1969 to ?1% during 1995-2007. However, the numbers of HFRS cases and deaths in China remain the highest in the world.

[Epidemiology and surveillance programs on hemorrhagic fever with renal syndrome in Mainland China, 2005 - 2008]

OBJECTIVE

To analyze the epidemiologic and surveillance data of hemorrhagic fever with renal syndrome (HFRS) in China, from 2005 to 2008, to describe the epidemiology and trend of HFRS.

METHODS

Descriptive epidemiology were studied to analyze the surveillance data from 2005 to 2008, collected from both the internet-based national notifiable disease reporting system and 40 HFRS sentinel sites developed since 2005 in 40 counties around China.

RESULTS

A total of 56 077 HFRS cases and 692 deaths reported in China with case fatality rate as 1.23%. Morbidity and mortality had been annually decreasing since 2004. The top 7 provinces with HFRS cases were Heilongjiang, Liaoning, Jilin, Shandong, Shaanxi, Hebei and Zhejiang, which had a total of 44 081 cases reported, accounting for 78.61% of the total number of cases, in the nation. More cases were reported in spring and autumn-winter season, with the peak in November. Cases reported in males were 3.13 times of the females and most cases seen in young and middle-aged farmers. The density and the virus carrying rate of animal hosts and the distribution of dominant species were relatively stable and similar to the previous findings. Apodemus agrarius and Rattus norvegicus were still the most common and predominant animal hosts. No genetic mutation of Hantavirus was detected in the surveillance program.

CONCLUSION

The continuous descending trend of the HFRS epidemics could be related to the successful strategies on comprehensive prevention and control measures, as controlling the number of rodents and vectors, carrying out HFRS vaccination campaign and health education by the local health care takers in the recent years. Implementation of the new national Expanded Program of Immunization on HFRS vaccine in high-risk areas may further reduce the epidemics. However, both the density and the virus carried rate among the host animals remain high in some areas, together with the emergence of new epidemic areas, all call for more attention to be paid on the disease.

[Epidemiological characteristics and the strategy of vaccination on hemorrhagic fever with renal syndrome in the last 10 years, in China]

OBJECTIVE

To study the epidemiological characteristics and vaccination strategy of hemorrhagic fever with renal syndrome (HFRS) in China, from 1998 to 2007.

METHODS

National data on the prevalence of HFRS during 1998 to 2007 were collected and analyzed. Spatial, time and population distributions of HFRS cases were described.

RESULTS

HFRS appeared to remain endemic in the country, while the majority of cases (accounting for 81.76% of total cases), were located in Shandong, Heilongjiang, Liaoning, Hebei, Shaanxi, Hunan, Jilin and Zhejiang provinces. The occurrence of HFRS appeared to be seasonal, with two peaks in spring season and autumn/winter season, with 10.00% of the cases occurred in these peak months. The incidence rates were at a relatively low level because of the continuous decline of HFRS in the recent years. With age distribution, 0.97% were younger than 10, 96.71% were between 10 and 70, 87.32% were between 15 and 60, and 2.31% were older than 70. The proportion of male patients accounted for three quarters. Around 70.00% of the cases were farmers. Young and middle-aged male farmers were at high risk.

CONCLUSION

The descriptive study on epidemiological characteristics of HFRS in the recent years had provided scientific evidence for vaccination strategy, suggesting the key regions, sub-populations as well as types of vaccines be determined.

[Immunogenicity of N-protein of Puumala hantavirus for noninbred mice in the intramuscular administration of its gene DNA]

The outbreaks of hantavirus infections in some regions of the Russian Federation in some years involve considerable material and social losses. In this connection, the designing of the most effective types of vaccines is an urgent task. The authors have created plasmid constructions containing the gene of hemorrhagic fever with renal syndrome virus, with whose Intramuscular injection there is a specific immune response and plasmid DNA is detectable in the adjacent tissues within a month after injection.

[Genotype and sequence analysis on G2 segments of hantavirus from HFRS patients in Hebei Province]

OBJECTIVE

To know the genotype and subtype of hantavirus (HV) which infected persons in Hebei province.

METHODS

According to G2 coding region of 76-118 and R22 strains, specific type primers were designed to detect and identity the types of HV in HFRS patients' sera with RT-nested PCR. Nucleotides were assayed from partial products after purification and reclaim. Then, gene analysis was done with DNAStar package.

RESULTS

17 out of 69 positive serum specimens were successfully detected by RT-PCR and the detection rate was 24.64%, among which, <or= 7 days was 34.29%, 8-14 days was 19.23%, >or= 14 days were 0. 17 positive specimens were all belonged to SEO. The nucleotide homology of 9 typical specimens was 92.0%-100%. Between HeB7 and other 8 specimens was 92%-95%, and they belonged to different subtypes. When HeB7 compared with R22 strain, it was 97.7%. HeB7 and R22 belonged to S1 subtype. The 8 specimens except HeB7 was 95.7%-100% and they all belonged to S3 subtype. When compared with 76-118 strain, 9 specimens' nucleotide homology was only 70.3%-72.7%, belonged to different type.

CONCLUSION

SEO was the major type of HV from HFRS patients in Hebei province, S3 was the major subtype and S1 was also existed. In a certain area, the HV which belonged to the same type was correspondingly conservative, and had the characteristic of regional stability.

[Study on a 10-year protective effects of vaccination against hemorrhagic fever with renal syndrome]

OBJECTIVE

To evaluate the epidemiological and serological efficacy after 10 years of vaccination against hemorrhagic fever with renal syndrome (HFRS) vaccines in Zhejiang province.

METHODS

One county was randomly chosen as the research unit with all the healthy people between 16 and 60 years old were equally divided into study and control groups. The study group was vaccinated. Immunofluorescent antibody assay was used to test specific IgG antibody and Mcro-CPE method was used to test the titer of neutralizing antibody.

RESULTS

Two weeks after the full-course immunization, the seroconversion rate became 100% (67/67, with 95% CI as 96.3%-100%) by immunofluorescent antibody test (IgG) and 44.4% (8/18 with 95% CI as 22.0%-69.0%) by neutralization test with GMT titers as 72.1 and 4.6 respectively. Booster immunization was provided one year later. Time span as two weeks prior to, one year, one and half years, two years, three years and five years after booster immunization, the rates of seroconversion on immunofluorescent antibody using IFAT method, were 28.6%, 83.3%, 75.0%, 53.1%, 22.6%, 10.0% and 55.0% respectively, and rates of seroconversion of neutralizing antibody by Mcro-CPE method were 14.8%, 55.6%, 35.0%, 31.3%, 26.0%, 10.0% and 50.0% respectively. Nine years after the reinforcement, the rates of seroconversion of immunofluorescent antibody by IFAT method was only 7.1%. The vaccinated group had no patient seen but the control group appeared 34 patients including 3 deaths. According to the ten-year observation, the vaccine seemed effective with the protection rate in population reached 100%.

CONCLUSION

HFRS vaccine was effective on epidemiological, social and economical efficacy.

[Epizootology of hemorrhagic fever with renal syndrome in the Central Chernozem Region]

A total of 5149 small mammals belonging to 16 species were collected from the Lipetsk, Voronezh, and Belgorod regions (40 administrative districts) in 2003-2004 and examined by ELISA and IFA to detect hantavirus antigen and antibodies in the lung tissues. Hantavirus circulation was revealed in 13 species, the highest hantavirus activity being detected in field (Apodemus agrarius) and small wood (A. (S) uralensis) mice (Dobrava-Belgrad virus), bank (Clethrionomis glareolus) (Puumala virus) and common (Microtus arvalis) (Tula virus) voles. These species were frequently found to have their untypical hantaviruses, which was most commonly observed in small wood mice. It is suggested that the small wood mouse is likely to take a certain part in maintaining the circulation of Dobrava-Belgrad virus.

Epidemiology of hemorrhagic fever with renal syndrome in endemic area of the Republic of Korea, 1995-1998

We conducted an epidemiologic study to understand temporal and spatial patterns of hemorrhagic fever with renal syndrome (HFRS) in the Republic of Korea (ROK). We estimated the incidence among civilians in endemic areas through the active surveillance system during the major epidemic periods, from September to December, between 1996 and 1998. We also estimated the prevalence among Korean military personnel from 1995 to 1998. In addition, we assessed seroprevalence, subclinical infection rate, and vaccination rates in both civilians and military personnel. The incidence in civilians ranged from 2.1 to 6.6 per 100, 000 person-months. The annual prevalence in the military personnel was 40-64 per 100, 000 military populations, and remained generally constant throughout the study period with seasonal variation. This is the prospective epidemiologic data set on HFRS in the ROK since the inactivated Hantaan virus vaccine was licensed for use in the late 1990s. These results will be invaluable in establishing a national immunization program against HFRS.

[Hemorrhagic fever with the renal syndrome: modern aspects of epidemiology and prophylaxis]

Hemorrhagic fever with the renal syndrome (HFRS) is a typical natural-and-focal virus infection having military-and-epidemiological importance for Armed Forces of most countries. Severe forms of this infection are typical for the Far East of Russia, countries of South-East Asia and especially for the American continent. The lethality from HFRS amounts to 15-50%. The main natural carriers and keepers of HFRS stimulus are various mouse-type rodents. In Russia besides well-studied natural focuses on the Far East, Siberia, Ural, Povolge other active HFRS focuses were determined not long ago (Moscow, Orel, Lipetsk, Tula and Voronezh regions, the territory of Big Sochi). A man is infected by an aerosol, forming during drying up of rodents' urine, feces, saliva containing HFRS virus. Vaccinal prevention of HFRS in Russia hasn't yet been worked out. Ribavirin is the most effective in the treatment for HFRS. The means of prevention of population and servicemen must exclude their contact with rodents both in natural conditions and in populated areas.

[The manifestation of necrophagy in the populations of rodents carrying the virus of hemorrhagic fever with renal syndrome]

The role of necrophagy in the epizootic manifestations of hemorrhagic fever with renal syndrome (HFRS) is first shown. By analyzing a great body of data obtained in the Saratov Region in 1982-2000, it has been established that the frequency of manifestations of necrophagy depends on many factors, the most important of which are a season, the size (density) of populations of small mammals, their species composition and the type of biotopes inhabited by these animals. Necrophagy is ascertained to be of great importance in HFRS foci as one of the alimentary routes of infection transmission in the parasitic systems. The presence or absence of necrophagy may serve as a preliminary test for the activity of HFRS foci.

[Hantavirus infection]

Hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS) are rodent borne viral zoonosis caused by hantavirus infection. HFRS and HPS cause epidemic in Eurasia continent and North and South American continent, respectively. Various species of wild rodents play as a reservoir animal in nature. Laboratory rat derived HFRS epidemic has also been reported in several countries including Japan. Recently, HFRS and HPS were classified to category 4 diseases in the Japanese law in which patient must be reported to municipality office. Since rat has widely been used in many institutions, prevention and control of the animal infection are quite important for both occupational hazard and research accomplishment point of view.

[Rodents as the vectors of infective agents in the natural foci of infections in the Moscow megapolis]

This work deals with the results of 40-year observations on the circulation of infective agents in the natural foci of infections (tularemia, leptospirosis, hemorrhagic fever with renal syndrome) among rodents and other small mammals in the territory of the Moscow. The monitoring of their frequency and the infection rates remains the main effective measure for the prophylaxis of dangerous infections among the population of the megapolis.

Inactivation of Hantaan Virus-Containing Samples for Subsequent Investigations outside Biosafety Level 3 Facilities

OBJECTIVES

The potential risk of accidental infection by hantaviruses in a clinical or research laboratory necessitates special precautionary measures. A biosafety program must address handling and disposal of infectious materials as well as appropriate virus inactivation or depletion procedures to permit necessary further processing of specimens outside the biosafety level 3 laboratory.

METHODS

To study the elimination of hantavirus infectivity, the effects of different chemical and physical inactivation and depletion procedures were investigated on Hantaan virus-containing materials. An infectivity assay for hantaviruses was utilised to verify these procedures which are commonly preceding investigations such as ELISA, flow cytometry analysis, Western blot or immunofluorescence assay.

RESULTS

Chemical inactivation with methanol, paraformaldehyde, acetone/methanol and detergent-containing lysis buffer as well as physical forces such as UV irradiation and filtration efficiently reduced viral infectivity in infected cells and their supernatants below the detection limit.

CONCLUSION

The virus inactivation and depletion methods described herein are suitable to prepare non-infectious samples for further use in immunological, virological and cell-biological assays.

Protective effectiveness of hantavirus vaccine

A case-control study in the Republic of Korea evaluated the protective effectiveness of the hantavirus vaccine. Point estimates showed increasing effectiveness with increasing numbers of doses received: 25% for one dose, 46% for two doses, and 75% for three doses. All 95% confidence intervals overlapped zero; therefore, the findings could be due to chance.

Hantaviruses: Immunology, Treatment, and Prevention

Hantaviruses are rodent-borne bunyaviruses that are associated with two main clinical diseases in humans: hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. It has been suggested that host-related immune mechanisms rather than direct viral cytopathology may be responsible for the principal abnormality (vascular dysfunction) in these syndromes. This review summarizes the current knowledge on hantaviral host immune responses, immune abnormalities, laboratory diagnosis, and antiviral therapy as well as the current approaches in vaccine development.

[Complex evaluation of endemicity level of the territory affected by hemorrhagic fever with renal syndorome]

A new formula for the calculation of the endemicity index of the territory affected by hemorrhagic fever with renal syndrome (HFRS) based on empiric data collected in the Volga region near Saratov in 1982-2000 is proposed. As found in this research 21% of the administrative districts of the region have a high endemicity level (with the average index for several years reaching 35 points), 8% of the districts have a medium enemicity level (20 points) and 71% of the districts--a low endemicity level (9 points). It is pointed out that under conditions of financial constraints territories with high and medium endemicity levels should be first examined for HFRS; these territories should also be given priority in prophylactic deratization in the field and human settlements.

[The epidemic characteristics and preventive measures of hemorrhagic fever with syndromes in China]

OBJECTIVE

To summarize and analyze the epidemic situation of hantaviruses including geographic distribution, types and prevalent intensity of epidemic areas of hantavirus for the last 30 years in China, and to discuss relative preventive measures.

METHODS

Collecting and analyzing the data of hantaviruses epidemics in China.

RESULTS

The annual number of cases of hantavirus disease rapidly increased from 3295 in 1970 to 115,804 in 1986 then sustained between 40,000 and 60,000 cases annually in the 1990's, and then decreased thereafter. The epidemic areas existed in all provinces except Qinhai and Xinjiang and there were the hospitalized cases of hantavirus disease reported in other provinces. In recent years, the prevalence of hantavirus infection had increased in some cities, and the seasonal distribution of the cases changed as well.

CONCLUSION

Data suggested that the new epidemic characteristics of hantaviruses had emerged in China suggesting that it was necessary to strengthen surveillance programs and to take comprehensive preventive measures for the control and prevention of hantaviruses in China.

[Serological surveillance on vaccine against hemorrhagic fever with renal syndrome]

OBJECTIVE

To observe the serological and epidemiological efficacy of hemorrhagic fever renal syndrome (HFRS) vaccine in Zhejiang province.

METHODS

Immunofluorescent antibody assay and Mcro-CPE method were used to test specific IgG antibody and the titer of neutralizing antibody.

RESULTS

Two weeks after the injection of the third dose, the sero-conversion rates by both immunofluorescent antibody test (IgG) and neutralization test were 100.0% (67/67) (95% CI: 96.3 - 100.0) and 44.4% (8/18)(95% CI: 22.0 - 69.0) with geometric mean titers (GMTs) 72.1 and 4.6 respectively. The rates of seroconversion of immunofluorescent antibody by immunofluorescence antibody assay (IFA) were 28.6%, 83.3%, 75.0%, 53.1%, 22.6%, 10.0% and 55.0% before reinforcement, two weeks, one year, one year and a half years, two years, three years and five years after reinforcement. The rates of neutralizing antibody seroconversion by the Mcro-CPE method were found as 14.8%, 55.6%, 35.0%, 31.3%, 26.0%, 10.0% and 50.0% respectively. We found some antibody dependent immunization enhancement phenomenon among the inoculated population, but further observation was needed.

CONCLUSION

HFRS vaccine was immunologically effective and the duration of serous antibody last long.

[Use of amixin in the therapy and prevention of some viral infections]

The trial of oral interferon inductor amixin for effectiveness in chronic viral hepatitis (CVH) and hemorrhagic fever with renal syndrome (HFRS) has shown that amixin in CVH improved general condition of the patients, removed yellowness of the skin and sclera, normalized activity of aminotransferases and blood bilirubin level. Virus replication was stopped in 25 and 1.6% in CVHB and CVGC, respectively. Amixin in HFRS was effective if received early. Preventive amixin therapy in population groups with high HFRS risk prevents development of HFRS and acute respiratory viral infection.