What Is a Hantavirus?

Hantavirus belongs to the Bunyaviridae family. It is a negative-stranded RNA virus with an envelope segment. The genome includes three fragments: L, M, and S, which encode the L polymerase protein, G1 and G2 glycoproteins, and nuclear protein. Hantavirus includes Hantaan virus (HTNV) that causes hemorrhagic fever with renal syndrome (HFRS), Seoul virus (SEOV), Puumala virus (PUUV), and dobravirus ( Dobrava virus (DOBV), a nameless virus (Sin Nombre virus (SNV)) that causes Hantavirus lung syndrome (HPS), New York virus (NYV), Black Creek Canal virus (BCCNV) , Bayou virus (BAYV), Andes virus (ANV), and a group of viruses whose relationship with human diseases is unclear, such as Prospect Hill virus (PHV), Thailand virus (Thailand virus) (THAIV), Tula virus (TULV), Thottapalayam virus (TPMV), Khabarovsk virus (KBRV), El Moro Canyon virus (ELMCV), Rio Segundo Virus (RIOSV), Isla Vista virus (ISLAV), Muleshoe virus (MULEV), Bloodland lake virus (BLLLV), Rio Mamore virus (RMV), Topografov virus (TOPV), etc. In recent years, with the application of new technologies and the discovery of new viruses, the research on Hantavirus and related diseases has developed rapidly. From March 5th to 7th, 1998, the 4th International HFRS and Hantavirus Conference was held in Atlanta, USA. Scholars and experts from all countries around the world exchanged the latest research methods and research results in this field.

Hantavirus

Hanta virus overview

Hantavirus classification and distribution

Hantavirus can be of two types: causing Hantavirus pulmonary syndrome (HPS), and the other causing Hantavirus renal syndrome hemorrhagic fever (HFRS). The former is mainly prevalent in the United States, and cases have been detected in Argentina, Brazil, Paraguay, Bolivia and Germany. Although China has not discovered it, it may happen. The main clinical manifestations are acute respiratory failure characterized by noncardiogenic pulmonary edema and high mortality (52.4% to 78.0%) after prodromal symptoms such as fever and headache around 4 days, and severe 3 to 7 days Death, the survivors recover quickly, without sequelae. The latter is common hemorrhagic fever with renal syndrome in China, and molecular biological research on it once again proves that its pathogenesis is mainly the direct pathogenic role of the virus, the kidney is an early primary damage to the organ, and the virus is the direct cause of kidney damage. factor.

Hantavirus laboratory diagnosis

The research of Hantavirus laboratory diagnosis mainly focuses on the application of recombinant antigens and the rapid, sensitive and specificity of laboratory diagnostic methods.

Hantavirus F. Elgh et al. Used PUU virus recombinant nuclear protein as antigen, linked with latex for latex microparticle agglutination test, used for rapid serological diagnosis of hantavirus disease, compared with ELISA using PUU virus recombinant nuclear protein as antigen, specificity It is 90% and the sensitivity is 94%. Jiro Arikawa et al. Used baculovirus-expressed HTN, SEO, and PUU nucleoproteins for ELISA, using at least two recombinant antigens (HTN and PUU or SEO and PUU), which can be used for serological monitoring of Hantavirus infection. Baculovirus expresses the N-terminally deleted HTN or SEO virus nuclear protein as an immunofluorescence test (IFA) antigen, which can distinguish HTN from SEO virus infection. Recombinant nucleoproteins and N-terminal deleted nucleoproteins are used in ELISA and IFA to provide a rapid, sensitive and safe diagnostic method for hantavirus infection. H. Kallio-Kokko et al. Used baculovirus-expressed PUU virus nuclear protein for IgG and IgM detection, E. coli-expressed PUU virus nuclear protein for IgM detection, and the sensitivity reached 100%. Some of the expressed nuclear proteins were used for IgG test with low sensitivity (70%). They also reported that in acute cases of PUU virus infection, two-thirds of cases can use RT-PCR tests to detect viral RNA from patients' blood or urine. T. Tomiyama et al. Coated high-density positive particles with purified hantavirus antigens, and used high-density particle agglutination test (HDPA) for rapid serological diagnosis of viral infections. They have a high sensitivity for the detection of HTN virus infection and Specificity, also has a low level of cross-reactivity to PUU, SN virus infection. Compared with IFA, HDPA has similar sensitivity, but it is easier and faster than IFA. W. Irwin et al. Reported the application of immunoblot test in the field investigation to the detection of murine virus antibodies. Qiu Jianming et al. Used 5-end biotin-labeled Hantan virus-specific oligonucleotide probes, combined magnetic separation technology and improved guanidine isothiocyanate-phenol one-step method to extract viral RNA and perform reverse transcription kits. PCR for detection of serum from patients with clinical HFRS. The positive detection rate of patient sera within 7 days was 100%, and the positive detection rate of patient sera between 8 and 14 days was 57.14%. After 15 days, the patient sera could still detect 22.73% positive. The amplified product was confirmed to be specific amplification by dot blot hybridization, which provided a specific, sensitive, rapid and direct diagnostic method for early diagnosis of HFRS patients.

Hantavirus gene analysis

Scholars from various countries have adopted the method of virus and host gene analysis to study the kinship between Hantavirus isolates or host animals, and the co-evolution of viruses and host animals.

Hantavirus hantavirus gene analysis

JWSong et al. Isolated two strains of PUU-associated virus from Korea's Eothenomys regulus and named them Muju (MUJ) virus. Two strains

Hantavirus The sequence of the 241bp fragment of the virus G2 gene was 1.2% different. The homology of the 241bp fragment of the G2 gene and the 208bp fragment of the S gene with the corresponding sequence of the PUU virus was 79.5% -83.4% and 80.3% -81.2%. L. Yashina et al. HTN virus isolated from Russian Far Eastern Rats (Clethrionomys), Apodemus and HFRS patients. The sequence homology of M fragments is 86% to 89%. SEO virus isolated from patients with light HFRS has the same M fragment sequence Source 97%. M. Drebot has reported for the first time that Canadian prairie voles carry a PH-like virus. The sequences of M and S fragments of SN virus in different provinces of Canada are 25% different. Compared with the SN virus strain in eastern Canada, the genetic sequence of the SN virus strain in western Canada is closer. Yong-Kyu Chu et al. Reported that the virus strain derived from Indonesian rattooth rat can be amplified by SEO-type specific primers. Sequence analysis of the 290bp M fragment showed a 7% difference from the SEO virus. Two strains were SEO viruses, and the other strain could be amplified by HTN-type specific primers. Sequence analysis of the 290bp M fragment showed a 1% difference from the THAI 749 strain. JWSong et al compared TUL virus from Poland with TUL virus from central Russia and Czechoslovakia. The nucleoprotein and G2 glycoprotein amino acid sequence homology is greater than 96%. Phylogenetic analysis shows that the TUL virus in Poland is the closest to the TUL virus in central Russia. , But there are differences. Another study by C. Sibold et al.-Phylogenetic analysis of nucleoprotein-encoding genes showed that Western Slovak TUL virus is similar to Czech TUL virus, Eastern Slovak TUL virus is similar to central Russia TUL virus; and the 3'-NCR system Occurrence analysis shows that the TUL virus in East Slovakia is similar to the TUL virus in West Slovakia and the Czech Republic. The authors believe that there is a possibility that the Eastern Slovak TUL virus is recombined from the Central European and Russian TUL viruses.

Hantavirus host animal gene analysis

Cytochrome B gene analysis methods are mostly used. WCBlack IV and others used microsatellite DNA analysis to determine the genetic relationship between deer and rat, and studied the way of transmission of hantavirus in the murine fossa.

Co-evolution of Hantavirus and host animal

Four Hantaviruses (HTN, PUU, SEO, KBR) exist in seven host animals in the south of the Russian Far East. Studies by L. Minskaya et al. Show that viruses isolated from non-main host animals are close in antigenicity to standard strains, but are genetically and molecularly isolated from main host animals.

Hantavirus Different viruses. A. Vaheri et al.'S research showed that the TOP virus isolated from Siberian lemmings and the KBR virus S fragment isolated from Oriental voles have homology nucleotide levels of 82% and amino acid levels of 96%; The fragment homology nucleotide level was 77% and the amino acid level was 87%. Phylogenetic analysis showed that the three viruses had a common origin, which was consistent with the phylogenetic analysis of the cytochrome B gene of the corresponding host animal, indicating that there was horizontal transmission between the host animals during the evolution of the three viruses. Among them, the 3'-NCR of TOP virus M and S fragments is the longest, and it may be the earliest among the three Hantaviruses. JWSong et al. Reported different HTN virus strains derived from Korean guinea pigs. The 324bp fragment of the M gene has 95% to 99% homology, the 424bp cytochrome B gene and the D-loop region of the mitochondrial DNA differ from 0% to 3.1%. In different regions of South Korea, the guinea pigs have the same genetic background, HTN virus has the same source, and no large mutation of HTN virus strain and its host animal has been found in South Korea. Phylogenetic analysis by Heiske A. et al. Showed that the PUU virus in western Europe is different from the PUU virus in Sweden, Finland, and Russia. The open reading frame genes of the S branch of the same branch of the PUU virus differ by less than 8%. The open reading frame of the fragment has a gene difference greater than 14%. The amino acid sequence of the same branch PUU virus nucleoprotein differs from 0% to 2%, and the amino acid sequence of different branch PUU virus nucleoprotein differs from 3% to 5%. Data indicate that the European palm back in different regions can be divided into several subclasses. This research supports the view that the PUU virus co-evolved with its host animals. L. Ivanov et al. Studied KBR virus originating from Oriental voles in the Far East of Russia. The results showed that there was a 0.5% to 4.0% genetic difference between different KRB virus strains. The relationship between the genetic difference and the rat-trapping area was greater than the relationship with the year of rat-trapping. , Indicating that there is a long-term co-evolution between KBR virus and Oriental voles.

Hantavirus vaccine and antiviral research

In recent years, great progress has been made in the development of HFRS vaccines. Some types of vaccines have been approved for production and use by the state, some have entered clinical observation, and some are being developed and tested in the laboratory. China has successfully developed and trial-produced three monovalent inactivated vaccines, which are safe and have good serological and epidemiological effects. The average protection rate in the short-term (1 year after basic immunization) and medium-term (2 years after basic immunization). Type II hamster vaccines were 97.81% and 88.73%, respectively; type Shanghai gerbil vaccines were 94.08% and 91.72%, respectively; type The gerbils of Tianyuan gerbils were 100.00%; the type brain germs were 88.45% and 100.00%, respectively. Phase II clinical trial of inactivated bivalent gerbil kidney vaccine. The total response rate is 2.5%. After 3 injections, the immunofluorescence antibody positive rate is 100.00%, and the neutralizing antibody positive rate is 87.6% (for type I virus).

Hantavirus And 96.3% (for type II virus), the positive conversion rate of a single serotype was 100.00%, and the positive conversion rate of both serotypes was 75.00%. Studies on Hantavirus-inactivated rat brain vaccine (Hantavax) produced in South Korea show that the positive rate of serum antibodies detected by immunofluorescence test and high-density particle agglutination test after one year of basic immunization was 42.5% and 45%, respectively, and the neutralization antibody positive rate 13%. After 1 year of basic immunization, the serum antibody positive rate was 92%, and the neutralizing antibody positive rate increased to 80%. In addition, D. Koletzki et al. Constructed a hepatitis B virus chimera carrying the hantavirus nuclear protein gene, immunized animals with and without the use of adjuvants, and produced specific antibodies against hepatitis B virus and hantavirus. K. Kamrud et al evaluated the Hantavirus expressed by naked virus DNA and alphavirus. Using phage display technology, C. de Carvalho Nicacio et al., Tuomas Heiskanen et al. And Liang Mifang et al. Developed recombinant antibodies against Hantavirus, which opened up prospects for future immunotherapy of HFRS. WESeverson et al. Reported the effect of ribavirin on Hantavirus replication.

Hantavirus molecular and cell biology

Scholars from various countries have conducted research on the molecular biology and cell biology of Hantavirus in many aspects. TMWelzel et al. And Bai Xuefan et al. Used gene fragment phage surface presentation technology to study the recognition site of the Hantavirus monoclonal antibody. E. Mackow et al. Prepared monoclonal antibodies against SN virus nuclear proteins expressed by baculovirus for serological typing of HPS-associated viruses, and studied the recognition sites of monoclonal antibodies through NY-1 virus nuclear protein mutations. . JWHooper et al. Transfected Vero-E6 cells with plasmid DNA containing Hantavirus antigenomics, and then detected the expressed NP and G1 and G2 glycoproteins by immunoprecipitation. However, polymerases could not be detected by biochemical and functional analysis. Protein, not detected

Laboratory diagnosis Infectious virus. Studies by B. Anheier et al. Showed that the localization of Hantavirus G1 and G2 polymers in the Golgi apparatus is guided by the G1 protein, and the G2 protein stabilizes the molecular localization. Changes in the amino acids of the G1 protein may change the structure of the G1 and then affect the formation of the polymer. Studies by EVRavkov et al. Have shown that the interaction of nuclear proteins of BCC virus and actin fibers may play an important role in the assembly and / or release of Hantavirus. BJMeyer et al. Used Northern hybridization, RNase protection test, RT-PCR, clone sequencing and other methods to study the continuous infection of Hantavirus in Vero-E6 cells.

Hantavirus epidemiology

The first case of HPS was found in Chile in 1995. Only 8 cases developed from October 1995 to July 1997, and 20 cases occurred from October to December 1997. They involved 11 regions across the country, with an average age of onset of 29.7 years and a mortality rate of 61%. Viral gene analysis showed that the disease was mainly caused by Andes virus. The authors believe that the increase in HPS cases is associated with an increase in the number of local Hantavirus host animals. A total of 639 HFRS91 cases occurred in Russia from 1978 to 1996, distributed in 61 of the 89 administrative regions, of which 96.4% came from the European part of Russia and 3.6% came from the Asian part. The average annual mortality rates were 4.0 / 100,000 and 0.6 / 100,000. . Serology and genotyping indicate that there are at least six serotypes of Hantavirus in Russia: HTN, PUU, SEO, TUL, KRB, TOP. 199 cases of HFRS occurred in Belgium from October 1995 to December 1996. The seasonal distribution showed small peaks in winter and spring and large peaks in summer and autumn. The patients were mainly infected with PUU serotype. A total of 21 cases of HPS occurred in Canada as of November 1997, distributed in three western provinces, with a case fatality rate of 33%. Epidemiological investigations have shown that host animals carrying the virus are distributed throughout the country, and the incidence of HPS is related to the opportunity to contact rodents. The host animal was detected to carry hantavirus from 16 of 17 seaports and 2 of 3 airfields in Japan. The authors proposed that a surveillance system should be established and corresponding precautions should be taken to check the virus infection rate in the population.

Hantavirus ecology

Changes in climate, rodent habitat conditions, rodent reproduction strength, population composition and other factors affect rat density, while host animal virus infection rates change continuously with time and place. Different rat densities, host animal virus infection rates, and opportunities for contact with the population affect the outbreak or spread of the disease. TSChiueh et al.'S seroepidemiological study in Taiwan showed that although there were no confirmed HFRS patients in the local area, Hantavirus infection was present in the host animals. Among occupational populations in contact with rodents and patients with chronic renal failure and fever, The serum antibody positive rate was higher. C. Ahlm et al. Reported that wild moose in northern Sweden had a lower Hantavirus infection rate. Yun-Tai Lee and others found that South Korean bats and brown-headed owls carry PUU virus. Studies by OAAlexeyev et al. Showed that the majority (74%) of PUU-positive European brown backs could not detect viral RNA or antigen and were not infectious. In addition, in order to show the relationship between the adaptability of Hantavirus strains to Vero-E6 cells and host animal species, L. Ivanov et al. Used mouse lung specimens to calculate Hantavirus antigen titer, virus isolation success rate, and virus isolation days, etc. The black-lined hamster is 0.32, the Dalin's hamster is 0.17, the oriental voles is 0.10, and the brown back is 0.06.

Hantavirus clinical

Multiple reports have investigated the sequelae of HFRS and HPS, and studies have shown that patients recovering from both diseases have abnormal kidney or lung function compared to healthy people. M. Howard et al. Investigated pregnant women with HPS and found that the prognosis of pregnant women with HPS is the same as that of other HPS patients. The fetuses of pregnant women with HPS are not significantly different from those of other pregnant women with respiratory distress syndrome. No vertical transmission of SN virus in humans was found in the study.

Hantavirus Pathology and Immune Response

HL Van Epps et al. Studied the response to human T lymphocytes infected by HTN virus, including nucleoprotein or G1 protein and T cell lines. Some T cell lines targeting nucleoproteins have cross-reactivity with unknown virus nucleoproteins. T cell lines of nucleoprotein or G1 protein did not cross-react with unknown virus proteins. This cross-reaction of human T cell lines that cause different Hantavirus disease (HFRS and HPS) strains is pathological

Hemodialysis It is of great significance in research and vaccine development. Another study conducted by FAEnnis et al. Isolated and isolated T cell lines from the blood of HPS patients. Some cell lines recognize regions that are relatively conserved among different hantavirus strains, but some T cell lines cannot recognize a single amino acid change of hantavirus. Other T-cell lines can recognize distantly related isolates, such as the corresponding regions of the Andes and Pumala virus. The autopsy results of C. Mansilla et al. On Andes virus lethal patients show that the pathological changes caused by Andes-HPS and SNV-HPS are similar to the distribution of viral antigens, but cases of Andes-HPS have congestive myocarditis and type lung monocyte activity, and There is more liver staining. M. Bharadwaj et al. Detected viral RNA from the trachea of Andes-HPS patients and suggested that Andean virus may be transmitted from person to person. Other reports have investigated the role of blood histamine and bradykinin, lipid peroxides, vasopressin, lysosomes, red cell membrane adenosine triphosphatase in pathological changes in HFRS. SCSt Jeor et al. Studied the continuous infection of SN virus in deer mice. Within weeks to months after infection, as the antibody level increased, the virus disappeared in the serum and the virus in other tissues decreased. Karen L. Hutchinson et al. Studied the infection of BCC virus in cotton wool rats. In the first few weeks after infection, quantitative PCR detected viral cRNA in tissues other than blood, and the viral cRNA decreased after 5 months. Only 5 months after infection Detected in the brain; infectious virus is present in the blood 1 week after infection, peaks at 2 weeks, and decreases significantly at 3 weeks; infectious virus can still be detected at low levels in the adrenal glands, liver, kidneys, and testicles 5 months after infection; The virus can be isolated in the urine 70 days after infection; BCC antibodies can be detected 14 days after infection. Studies by Yang Shoujing et al. Have shown that HFRS shock and ischemia-induced ischemia can cause heat shock response, and 72KD and 73KD heat shock proteins are expressed in patient tissues to protect tissue cells from damage. In their other study, the detection of proliferating cell nuclear antigens and vimentin antibodies during cell division showed that during HFRS tissue damage, there was cell regeneration and DNA repair. The degree of repair was related to the severity of the damage.

HFRS is one of the viral diseases that seriously endanger the health of our people. Since the successful isolation of the virus in the early 1980's, research on HFRS and Hantavirus has achieved a lot of results, especially the development of inactivated vaccines in recent years, which has created conditions for effective prevention of the disease. However, we still have gaps with foreign research in the areas of etiology, laboratory diagnosis, immunopathology, and molecular biology, and there are still many problems to be solved. With the deepening of the research in the future, the gradual deepening of the understanding of the disease can finally effectively control the epidemic in China.

Hantavirus treatment principles

Hantavirus early antiviral therapy

The onset of HFRS is mainly caused by the direct action of the virus. The duration of viremia and peripheral blood mononuclear cells is generally 7 to 10 days or longer. Early antiviral treatment can block pathological damage, reduce disease and reduce mortality . Interferon and ribavirin have a positive effect. Can be applied within 7 days of illness, the course of treatment is 5-7 days.

Hantavirus rational comprehensive fluid therapy is the most important treatment

Preventive treatment should be emphasized, and there are different principles of fluid therapy in different stages. It is mainly based on balanced salt solution, and its composition and dosage are appropriately adjusted according to the results of laboratory tests. Hypoproteinemia should be actively corrected.

Hantavirus prevents kidney damage early

The degree of kidney damage during fever is relatively minor. Renal damage is aggravated by a variety of factors, such as plasma exudation, blood concentration, insufficient blood volume, and DIC. Therefore, corresponding measures should be taken in response to the above factors, which is an important strategy to improve the outcome of this disease.

Hantavirus oliguria uremia and various complications

For example, high blood volume, high blood pressure, heart failure, pulmonary edema, massive hemorrhage, comorbidities of the nervous system, and renal rupture are the five major causes of death. They all occur during the acute uremia of renal failure. Important means of saving lives should be widely used.

U.S. national park outbreak of hantavirus

A fatal Hantavirus infection has recently appeared in the camping area of Yosemite National Park, a resort in California, the United States. As of September 7, the death toll has risen to three.

It is reported that the third deceased person came from the state of West Virginia in the United States. The total number of confirmed Hantavirus infections has reached 8 and is likely to continue to rise.

The two previous dead were from California and Pennsylvania. The others were from California, and park staff said their condition had eased.

U.S. health officials have reportedly warned 39 countries that citizens of the country who had camped in Yosemite National Park this summer could be infected with the deadly Hantavirus.

Experts said that about 10,000 people were at risk of contracting Hantavirus lung syndrome because they visited Yosemite National Park between June and August, and about 2,500 were from countries outside the United States. There is currently no cure for the disease, but early detection through blood tests can greatly increase the chances of survival.