[Severe acute respiratory syndrome (SARS)--new, unknown disease?]

Severe Acute Respiratory Syndrome (SARS) caused by new corona--virus SARS-Co-V was not identified at humans and animals up to this time. A characteristic feature of this disease is biphasic course. First high fever, parainfluenza syndrome followed by increasing respiratory distress. The main role in transmission is droplet way, things contaminated by excreta, blood transfusion is not excluded. Pathomorphological changes are: bronchial epithelial denudation, loss of cilia, squamous metaplasia, a giant cells infiltrate of macrophages in the alveoli, haemophagocytosis, atrophy white pulp of the spleen. Diagnosis is based on clinical picture and epidemiological data supported by positive serology, PCR or presence virus in cell culture. In treatment ribavirin, steroids and mechanical ventilation are used.

[Study on the correlation between positive rates of SARS RNA in clinical confirmed SARS patients and the appearance of RNA in relation to the development of the disease]

OBJECTIVES

To study the correlation between positive rates of RNA in clinical confirmed severe acute respiratory syndrome (SARS) patients and its appearance in relation to the development of the disease in order to provide scientific basis for early diagnosis, effective prevention and treatment of the disease.

METHODS

One-step reverse transcription-polymerase chain reaction (RT-PCR) was used to amplify the SARS RNA in the clinical specimens from different courses of the disease. The representative amplicons were then sequenced. Chi-square for trend test was performed to study the correlation between positive rates of RT-PCR and at different periods after the onset of the disease.

RESULTS

The fragments amplified from the sputum specimens of SARS patients were shown to share 100% homology with the published SARS-associated coronavirus. Of the different clinical specimens, positive rate in the stools appeared to be the highest (21.55%). Chi-square for trend test revealed that the positive rates of stools and sputa of SARS patients decreased with the development of the disease (chi(2) for trend = 12.55 and 16.408, P = 0.0004 and P = 0.000 05 respectively).

CONCLUSION

One-step RT-PCR proved to be an effective method for the detection of SARS-associated coronavirus from clinical specimens. Data as indicated that the positive rates of SARS coronavirus were decreasing in SARS patients along with the disease progression.

SARS-associated viral hepatitis caused by a novel coronavirus: report of three cases

Liver impairment is commonly reported in up to 60% of patients who suffer from severe acute respiratory syndrome (SARS). Here we report the clinical course and liver pathology in three SARS patients with liver impairment. Three patients who fulfilled the World Health Organization case definition of probable SARS and developed marked elevation of alanine aminotransferase were included. Percutaneous liver biopsies were performed. Liver specimens were examined by light and electron microscopy, and immunohistochemistry. Reverse-transcriptase polymerase chain reaction (RT-PCR) using enhanced real-time PCR was applied to look for evidence of SARS-associated coronavirus infection. Marked accumulation of cells in mitosis was observed in two patients and apoptosis was observed in all three patients. Other common pathologic features included ballooning of hepatocytes and mild to moderate lobular lymphocytic infiltration. No eosinophilic infiltration, granuloma, cholestasis, fibrosis, or fibrin deposition was noted. Immunohistochemical studies revealed 0.5% to 11.4% of nuclei were positive for proliferative antigen Ki-67. RT-PCR showed evidence of SARS-associated coronavirus in the liver tissues, but not in the sera of all 3 patients. However, electron microscopy could not identify viral particles. No giant mitochondria, micro- or macro-vesicular steatosis was observed. In conclusion, hepatic impairment in patients with SARS is due to SARS-associated coronavirus infection of the liver. The prominence of mitotic activity of hepatocytes is unique and may be due to a hyperproliferative state with or without disruption of cell cycle by the coronavirus. With better knowledge of pathogenesis, specific therapy may be targeted to reduce viral replication and modify the disease course.

[Development and evaluation of the kit for detection of SARS-associated Coronavirus RNA]

AIM

To develop a diagnostic kit for detection of SARS (severe acute respiratory syndrome)-related coronavirus RNA based on reverse transcription and polymerase chain reaction and to estimate its specificity and sensitivity.

MATERIAL AND METHODS

68 virus and bacterial cultures, 240 clinical samples from people without SARS symptoms and also 22 RNA samples from patients with SARS symptoms received during the epidemic in Beijing were used.

RESULTS

The specificity of the kit was determined using animal coronaviruses and other bacterial and viral strains, causing acute respiratory and intestinal infections, and was shown to be 100%. The sensitivity of the kit in different clinical samples was 2.2 x 10(3) genome equivalents of recombinant SARS RNA in 1 ml of the specimen. The kit was evaluated in the Institute of Microbiology and Epidemiology of Beijing (China) using SARS-cov viral suspension and clinical samples from patients with suspected SARS. It was shown that kit was able to detect 10 TCID/50 ml of SARS-Cov virus. Testing of clinical samples from patients with suspected SARS showed that diagnostic sensitivity of the kit was 95%. Detection of the SARS-Cov RNA was more effective in feces compared to sputum 990 and 40%, respectively).

CONCLUSION

The kit "AmpliSens SARS" for qualitative detection of SARS-related coronavirus RNA by reverse transcription and polymerase chain reaction (PCR) in nasopharyngeal wash/aspirates, naso/oropharyngeal swabs, plasma, and extract from feces has been developed in the Central Research Institute for Epidemiology of the RF Ministry of Health. The kit contains reagents for RNA isolation and purification, cDNA synthesis by reverse transcription of RNA, for PCR and for electrophoretic analysis of amplified products. The kit also contains recombinant positive and internal control samples allowing to control efficiency of analysis and showed good analytical and diagnostic characteristics.

[Pathologic study of circulating blood leukocytes in severe acute respiratory syndrome]

OBJECTIVE

To study the pathologic characteristics and pathogenesis of circulating blood leucocytes infected by severe acute respiratory syndrome associated coronavirus (SARS CoV or SCV) in SARS patients.

METHODS

Blood samples of 22 SARS patients were studied, and 4 healthy blood samples were observed as negative controls. The white blood cells were collected from whole blood. The ultrastructural characteristics were observed by transmission electron microscopy. CD45RO antibody was used for pre-embedding immunoelectron microscopy. The SARS viral sequence was detected with real-time polymerase chain reaction (RT-PCR).

RESULTS

Coronavirus-like particles were founded in the leukocytes in 6 of the 22 blood samples. Five of them gave positive results in the real-time PCR. The number of granulocytes was increased (P < 0.05) and that of lymphocytes was decreased (P < 0.05) respectively. Immunoelectron microscopy showed that CD45RO positive T lymphocyte decreased to 6% - 7%. Circulating lymphocytes had the highest percentage of infection. The morphologic characteristics of coronavirus-like particles were spherical or oval in shape, about 80 - 120 nm in diameter, with a dense round core and a clear halo around the core. A distinct membrane and club-shaped surface projections were seen in the periphery. The particles were located in the cytoplasm, the cisternae of endoplasmic reticulum, Golgi apparatus and vesicles. Virus entered cells by endocytosis or membrane fusion and was released through a budding process.

CONCLUSION

Our data suggested that lymphocytes, particularly T cells, were probably the target cells of SARS CoV. The viruses may actively infected the immune cells during SARS CoV acute infection phase and the destruction of target cells may be one of the important reasons for the death of the circulating leukocytes in SARS.

The virus that changed my world

Personal account of a young virologist working in Singapore at the height of the 2003 SARS pandemic

Severe acute respiratory syndrome (SARS) in Hong Kong: patients' experiences

BACKGROUND

This past year there was an outbreak of Severe Acute Respiratory Syndrome (SARS) in Hong Kong. During that time we investigated the clinical features, treatment, and nursing care of 36 patients and reported on 12 of these patients' perceptions of their illness experience.

PURPOSE

The purpose of this article is to describe the clinical features, treatment, nursing care and perceptions of the illness experience of patients with SARS in Hong Kong in order to better inform nurses caring for patients with this highly contagious and potentially lethal disease.

METHOD

We abstracted data from the medical and nursing records on the clinical features, treatment and nursing care of 36 patients (21 women, 15 men) in whom SARS was diagnosed and who were admitted to the Queen Mary Hospital in Hong Kong between March 15 and April 15, 2003. A review of the hospital's policy and procedures on infection control was also undertaken. Semi-structured interviews were conducted with 12 of the patients to elicit their perceptions of the illness experience.

FINDINGS

The most common symptoms were cough (83%), dyspnea (80.6%), malaise (69.4%) and fever (61%). Less common symptoms included headache (38.9%), diarrhea (38.9%), dizziness (30.6%), myalgia (25%), chills (19.4%), nausea and vomiting (19.4%) and rigor (the occurrence of a sensation of hot-and-cold and shivering in addition to teeth chattering and bed shaking) (8.3%). All 36 patients received a combination of corticosteroids and ribavirin. The patients were at risk of drug-related adverse reactions and deterioration of respiratory function, and nursing vigilance was required.

CONCLUSION

Nursing patients with SARS was challenging as the disease was highly contagious and potentially lethal, and not much was known about this disease. In addition to the use of frontline treatment, infection control and sensitivity to individual responses to sudden and catastrophic illness were required to support these patients. From this outbreak of SARS, we have learned the importance of infection control in containing and controlling the disease. Other lessons included the need to strengthen the surge capacity in our hospitals and support health care workers during the crisis.

Virology: SARS virus infection of cats and ferrets

There is now a choice of animal models for testing therapies against the human virus.

The reservoir of the coronavirus isolated from patients with severe acute respiratory syndrome (SARS)^1,2 is still unknown, but is suspected to have been a wild animal species. Here we show that ferrets (Mustela furo) and domestic cats (Felis domesticus) are susceptible to infection by SARS coronavirus (SCV) and that they can efficiently transmit the virus to previously uninfected animals that are housed with them. The observation that these two distantly related carnivores can so easily be infected with the virus indicates that the reservoir for this pathogen may involve a range of animal species.

[Morphological study of severe acute respiratory syndrome (SARS)]

OBJECTIVE

Seven cases of autopsy from SARS patients are studied to investigate the pathogenesis and the pathologic changes of the major organs.

METHODS

Detailed gross and microscopic examination of the autopsy specimen is performed, including lung, heart, liver, kidney, spleen and lymph nodes.

RESULTS

All of the lungs are markedly enlarged and consolidated. Microscopically, pulmonary edema is a prominent finding, especially at the early stage of the disease (5 days after the onset). The alveolar spaces are filled with fibrinous exudates and lined with hyaline membrane. In 5 cases that undergo over 3 weeks of the course, the main pattern is organization of intra-alveolar deposit, along with fibroblastic proliferation in the alveolar septa, which leads to obliteration of alveolar space and pulmonary fibrosis. All of the lungs show bronchopneumonia, scattered hemorrhage, and proliferation of alveolar epithelial cells with desquamation. Microthrombi are seen in 6 cases. Fungal infection is noted in 2 cases. One of them is disseminative, involving bilateral lungs, heart, and kidney; the other one is diagnosed in hilar lymph nodes. In immune system, hilar and abdominal lymph nodes are usually congested and hemorrhagic, with depletion of lymphocytes, and accompanied with subcapsular sinus histiocytosis. One of the cases shows enlargement of abdominal lymph nodes, which have reduced number of germinal centers. Spleen exhibits atrophy of white pulps, and even lost of white pulps in some areas. The red pulp is markedly congested and hemorrhagic. In 5 cases, cardiomegale is prominent. Thrombosis (2 cases), focal myocarditis (1 case), and fungal myocarditis (1 case) are observed. In addition, liver shows massive necrosis (1 case) and nodular cirrhosis (1 case).

CONCLUSIONS

Lung is the major organ affected by SARS, demonstrated as diffuse alveolar damage. It is postulated that viral infection induces severe damage of alveolar epithelial and capillary endothelial cells, leads to pulmonary edema, intra-alveolar fibrin deposit, and hyaline membrane formation. Consequently, intra-alveolar organization and alveolar septal fibrosis causes loss of alveolar spaces, eventually, pulmonary fibrosis and atelectasis. The immune system is often affected, and presented as depletion of lymphoid tissue in lymph nodes and spleen. Secondary infection is a common complication, which should be paid close attention in the management of SARS patients.

SARS: radiological features

Air-space disease is typical in severe acute respiratory syndrome (SARS) and may be indistinguishable from pneumonia of other causes. In the majority of patients, ground glass opacities on chest radiographs progress rapidly to focal, multifocal or diffuse consolidation. Unilateral involvement is common in the early acute phase, becoming bilateral at maximal lung involvement. Generally, radiographic opacities peak between 8 and 10 days after onset of illness, with radiographic scores reflecting temporal changes in clinical and laboratory parameters such as oxygen saturation (SaO2) and liver transaminases. Pleural effusions, cavitating consolidation and mediastinal lymphadenopathy are not typical radiographic features. Pneumomediastinum and pneumothoraces are complications that are associated with extensive disease, with or without assisted ventilation. The utility of high resolution computed tomography (HRCT) and CT scans lies in the confirmation of airspace opacities in cases with normal initial chest radiographs that have strong contact history and signs and symptoms highly suspicious of SARS during the outbreak, allowing early treatment and prompt isolation. The characteristic HRCT feature in the acute phase is ground-glass opacities with smooth interlobular septal thickening, sometimes with consolidation in a subpleural location, which progress rapidly to involve other areas of the lungs. Temporal lung changes documented on HRCT suggest that some residual opacities found may not be reversible.

Lung pathology of severe acute respiratory syndrome (SARS): a study of 8 autopsy cases from Singapore

Severe acute respiratory syndrome (SARS) is an infectious condition caused by the SARS-associated coronavirus (SARS-CoV), a new member in the family Coronaviridae. To evaluate the lung pathology in this life-threatening respiratory illness, we studied postmortem lung sections from 8 patients who died from SARS during the spring 2003 Singapore outbreak. The predominant pattern of lung injury in all 8 cases was diffuse alveolar damage. The histology varied according to the duration of illness. Cases of 10 or fewer days’ duration demonstrated acute-phase diffuse alveolar damage (DAD), airspace edema, and bronchiolar fibrin. Cases of more than 10 days’ duration exhibited organizing-phase DAD, type II pneumocyte hyperplasia, squamous metaplasia, multinucleated giant cells, and acute bronchopneumonia. In acute-phase DAD, pancytokeratin staining was positive in hyaline membranes along alveolar walls and highlighted the absence of pneumocytes. Multinucleated cells were shown to be both type II pneumocytes and macrophages by pancytokeratin, thyroid transcription factor-1, and CD68 staining. SARS-CoV RNA was identified by reverse transcriptase-polymerase chain reaction in 7 of 8 cases in fresh autopsy tissue and in 8 of 8 cases in formalin-fixed, paraffin-embedded lung tissue, including the 1 negative case in fresh tissue. Understanding the pathology of DAD in SARS patients may provide the basis for therapeutic strategies. Further studies of the pathogenesis of SARS may reveal new insight into the mechanisms of DAD.

Enteric involvement of severe acute respiratory syndrome-associated coronavirus infection

BACKGROUND AND AIMS

Severe acute respiratory syndrome (SARS) is a recently emerged infection from a novel coronavirus (CoV). Apart from fever and respiratory complications, gastrointestinal symptoms are frequently observed in patients with SARS but the significance remains undetermined. Herein, we describe the clinical, pathologic, and virologic features of the intestinal involvement of this new viral infection.

METHODS

A retrospective analysis of the gastrointestinal symptoms and other clinical parameters of the first 138 patients with confirmed SARS admitted for a major outbreak in Hong Kong in March 2003 was performed. Intestinal specimens were obtained by colonoscopy or postmortem examination to detect the presence of coronavirus by electron microscopy, virus culture, and reverse-transcription polymerase chain reaction.

RESULTS

Among these 138 patients with SARS, 28 (20.3%) presented with watery diarrhea and up to 38.4% of patients had symptoms of diarrhea during the course of illness. Diarrhea was more frequently observed during the first week of illness. The mean number of days with diarrhea was 3.7 +/- 2.7, and most diarrhea was self-limiting. Intestinal biopsy specimens obtained by colonoscopy or autopsy showed minimal architectural disruption but the presence of active viral replication within both the small and large intestine. Coronavirus was also isolated by culture from these specimens, and SARS-CoV RNA can be detected in the stool of patients for more than 10 weeks after symptom onset.

CONCLUSIONS

Diarrhea is a common presenting symptom of SARS. The intestinal tropism of the SARS-CoV has major implications on clinical presentation and viral transmission.

[Immunohistochemical investigation of lungs with severe acute respiratory syndrome]

OBJECTIVE

To investigate the roles of different cells in the pulmonary lesions in the severe acute respiratory syndrome (SARS) patients.

METHODS

The monoclonal antibodies of CD8, CD20, CD34, LCA, CD56, CD68, and AE1/AE3 are used to demonstrate the different cells in the lung specimens of SARS patients in order to study the patterns of cell responses in this new disease. Meanwhile the HE stained slides were also carefully studied to compare with the results of immunohistochemical staining.

RESULTS

The number of capillaries increased and the capillaries clearly outlined the contour of alveolar wall from beginning to early stage of organization, the number of lymphocytes decreased sharply while the number of macrophage remarkably increased, together with proliferation of type II pneumocytes. The numbers of blood vessels decreased in the fibrotic and consolidated lung tissue, and the vessel cavities enlarged, losing the normal contour of alveolar septa.

CONCLUSIONS

The lesions in the lung from SARS patients are consisted of the tissue reaction to the inflammatory injury, including extensive exudation, capillary proliferation, fibrosis, and obvious infiltration of macrophages which may play a key role in the pathogenesis of pulmonary lesions of SARS.

Enteric involvement of severe acute respiratory syndrome-associated coronavirus infection

BACKGROUND AND AIMS

Severe acute respiratory syndrome (SARS) is a recently emerged infection from a novel coronavirus (CoV). Apart from fever and respiratory complications, gastrointestinal symptoms are frequently observed in patients with SARS but the significance remains undetermined. Herein, we describe the clinical, pathologic, and virologic features of the intestinal involvement of this new viral infection.

METHODS

A retrospective analysis of the gastrointestinal symptoms and other clinical parameters of the first 138 patients with confirmed SARS admitted for a major outbreak in Hong Kong in March 2003 was performed. Intestinal specimens were obtained by colonoscopy or postmortem examination to detect the presence of coronavirus by electron microscopy, virus culture, and reverse-transcription polymerase chain reaction.

RESULTS

Among these 138 patients with SARS, 28 (20.3%) presented with watery diarrhea and up to 38.4% of patients had symptoms of diarrhea during the course of illness. Diarrhea was more frequently observed during the first week of illness. The mean number of days with diarrhea was 3.7 +/- 2.7, and most diarrhea was self-limiting. Intestinal biopsy specimens obtained by colonoscopy or autopsy showed minimal architectural disruption but the presence of active viral replication within both the small and large intestine. Coronavirus was also isolated by culture from these specimens, and SARS-CoV RNA can be detected in the stool of patients for more than 10 weeks after symptom onset.

CONCLUSIONS

Diarrhea is a common presenting symptom of SARS. The intestinal tropism of the SARS-CoV has major implications on clinical presentation and viral transmission.

Enteric involvement of severe acute respiratory syndrome-associated coronavirus infection

BACKGROUND AND AIMS

Severe acute respiratory syndrome (SARS) is a recently emerged infection from a novel coronavirus (CoV). Apart from fever and respiratory complications, gastrointestinal symptoms are frequently observed in patients with SARS but the significance remains undetermined. Herein, we describe the clinical, pathologic, and virologic features of the intestinal involvement of this new viral infection.

METHODS

A retrospective analysis of the gastrointestinal symptoms and other clinical parameters of the first 138 patients with confirmed SARS admitted for a major outbreak in Hong Kong in March 2003 was performed. Intestinal specimens were obtained by colonoscopy or postmortem examination to detect the presence of coronavirus by electron microscopy, virus culture, and reverse-transcription polymerase chain reaction.

RESULTS

Among these 138 patients with SARS, 28 (20.3%) presented with watery diarrhea and up to 38.4% of patients had symptoms of diarrhea during the course of illness. Diarrhea was more frequently observed during the first week of illness. The mean number of days with diarrhea was 3.7 +/- 2.7, and most diarrhea was self-limiting. Intestinal biopsy specimens obtained by colonoscopy or autopsy showed minimal architectural disruption but the presence of active viral replication within both the small and large intestine. Coronavirus was also isolated by culture from these specimens, and SARS-CoV RNA can be detected in the stool of patients for more than 10 weeks after symptom onset.

CONCLUSIONS

Diarrhea is a common presenting symptom of SARS. The intestinal tropism of the SARS-CoV has major implications on clinical presentation and viral transmission.

[Clinical and chest X-ray characteristics of 5 cases with severe acute respiratory syndrome in children in Shenzhen area]

OBJECTIVE

To explore clinical and chest X-ray features of SARS in children to facilitate correct diagnosis.

METHODS

Clinical manifestations and chest X-ray findings in five children suffering from SARS admitted for treatment in the hospital between February and May, 2003 in Shenzhen area were analyzed. The diagnosis was confirmed by epidemiological, clinical, laboratory and radiological examinations. Among the 5 cases, 1 was a boy and the others were girls at the age of 4 to 13 years.

RESULTS

Of the 5 SARS children, 3 presented a history of close contact with SARS patients. Fever was the initiative symptom, 4 had a body temperature of over 38 degrees C with the highest being 40 degrees C; fever sustained from 4 to 7 days with an average of 5.6 days. All the 5 cases developed nonproductive cough; on auscultation, both moist and dry rales could be heard in 3 out of the 5 cases. Mean total white count of peripheral blood was (2.96 - 6.9) x 10(9)/L, and was < 5.0 x 10(9)/L in 4 cases. SARS associated coronavirus specific RNA fragment was found positive by RT-PCR in 1 case; 1 case was positive for both IgM and IgG antibodies to the virus; 1 case was positive for only IgM antibody and another 2 cases were positive for only IgG antibody. IgG and IgM antibodies to Mycoplasma pneumoniae and Chlamydia pneumoniae as well as blood culture for bacteria were all negative. Findings on chest X-ray examination: 4 cases showed presence of patchy or macular opacities with cord-like shadows in unilateral lung plates while 1 case each showed ground-glass-like opacity and migratory changes; 1 case showed interstitial changes in the lungs in the form of irregular reticular lattice and cord-like shadows. Two cases received CT scanning and macular-patchy or spotty shadows were seen all over the lung. The shortest time for absorption of foci in the lungs was 7 days while the longest was 33 days with a mean of 15 +/- 6 days. None of the cases had any signs of fibrosis in the lungs. All the 5 cases were completely cured and discharged 7 to 40 days (mean 18 +/- 11 days) after admission.

CONCLUSION

Compared with adult cases with SARS, children with SARS had milder symptoms and signs. Presence of unilateral patchy shadow in lungs represented the main chest X-ray findings.

[Clinical pathology and pathogenesis of severe acute respiratory syndrome]

BACKGROUND

To explore the pathological features and pathogenesis of severe acute respiratory syndrome (SARS) to provide evidence for the clinical treatment and prevention of SARS.

METHODS

Pathological features of 2 cases of full autopsy and 4 cases of needle biopsy tissue samples from the patients who died from SARS were studied by light and electron microscopy. The distribution and quantity of lymphocyte subpopulations in the lungs and immune organs from SARS patients were analyzed by immunohistochemistry. The location and semi-quantitative analysis of SARS coronavirus in the tissue specimens were studied by electron microscopy, in situ hybridization and immunohistochemistry.

RESULTS

In total of 6 cases, diffuse alveolar damage and alveolar cell proliferation were common. The major pathological changes of 2 autopsy cases of SARS in lung tissues were acute pulmonary interstitial and alveolar exudative inflammation, and 2 autopsy and one biopsy lung tissues showed alveolar hyaline membrane formation. Terminal bronchiolar and alveolar desquamation of lung tissues in one autopsy and 2 biopsy cases were noted. Among 6 cases, 2 biopsy cases presented early pulmonary fibrosis and alveolar organization. Meanwhile, the immune organs, including lymph nodes and spleens from 2 autopsy cases of SARS whose disease courses were less than 12 days showed extensive hemorrhagic necrosis, reactive macrophage/histocyte proliferation, with relative depression of mononuclear and granulocytic clones in the bone marrows. However, spleen and bone marrow biopsy tissue samples from 4 dead SARS cases whose clinical course lasted from 21 to 40 days presented repairing changes. SARS coronaviruses were mainly identified in type I and II alveolar epithelia, macrophages, and endothelia; meanwhile, some renal tubular epithelial cells, cardiomyocytes, mucosal and crypt epithelial cells of gastrointestinal tracts, parenchymal cells in adrenal glands, lymphocytes, testicular epithelial cells and Leydig's cells were also detected by electron microscopy combined with in situ hybridization. The semi-quantitative analysis of lymphocyte subpopulations revealed that the proportion of CD8+ T lymphocytes were about 80% of the total infiltrative inflammatory cells in the pulmonary interstitium, with a few CD4+ lymphocytes CD3+, CD4+, CD8+ or CD20+ lymphocyte subpopulations were obviously decreased and there was imbalance in number and proportion, while CD57+, CD68+, S-100+ and HLA-DR+ cells were relatively increased in lymph nodes and spleens.

CONCLUSIONS

Histologically, the pulmonary changes could be divided into acute inflammatory exudative, terminal bronchiolar and alveolar desquamative and proliferative repair stages or types during the pathological process of SARS. SARS coronavirus was found in multi-target cells in vivo, which means that SARS coronavirus might cause multi-organ damages which were predominant in lungs. There were varying degrees of decrease and imbalance in number and proportion of lymphocyte subpopulations in the immune organs of the patients with SARS. However, these changes may be reversible. It was found that cellular immune responses were predominant in the lungs of SARS cases, which might play an important role in getting rid of coronaviruses in infected cells and inducing immune mediated injury.

[Isolation and identification of the infective agent of severe acute respiratory syndrome (SARS) from a patient with atypical pneumonia]

The virological, morphological, molecular biological and immunochemical study of the infective agent isolated from the patient with the symptoms of atypical pneumonia, hospitalized in the infectious department of the clinical hospital in Blagoveshchensk, was carried out. Thus the fact of the appearance of SARS virus on the territory of Russia was proved. The isolated infective agent, identified as coronavirus strain CoD, was partly characterized and deposited to the virus collection of the Center of Special Laboratory Diagnostics and Treatment of Quarantine and Exotic Infectious Diseases.

[Detection of cell apoptosis in the pathological tissues of patients with SARS and its significance]

OBJECTIVE

To explore the role and mechanism of apoptosis in severe acute respiratory syndrome (SARS).

METHODS

Klenow-FragELTM DNA Fragmentation Detection Kit and immunohistochemical alkaline phosphatase detection reagent kit were used to detect cell apoptosis and expressions of CD68, CD20, CD4, CD8 and CD45RA in the pathological tissues of SARS patients.

RESULTS

Apoptotic cells increased significantly in the spleen, lung and lymph nodes of SARS patients as compared with normal tissues. The apoptotic cells included pneumocytes, lymphocytes and monocytes, and CD68+ monocytes were observed in abundance in the lung, spleen and lymph nodes of SARS patients. In the lung tissue of the patients, few CD20+/CD45RA+ B cells and CD4+/CD8+ T cells were spotted, and CD20+/CD45RA+ B cells along with CD4+/CD8+ T cells were also significantly decreased in the spleen and lymph nodes, where few conserved B and T cells underwent apoptosis.

CONCLUSIONS

Apoptosis is a general phenomenon in SARS, and the invasive cells in the pathological tissues are primarily monocytes, suggesting that apoptosis and invasion of monocyte play important roles in the progression of SARS. The cell apoptosis and decreased number of T cell and B cells in the lungs and CD4+/CD8+ T cells and CD20+/CD45RA+ B cells in the spleen and lymph nodes indicate that the SARS virus may exercise immune cell-killing effect to some extent during its pathogenesis.

[Expression of immune cells and their roles in the involved tissues of SARS patients]

OBJECTIVE

To study the expression of the immune cell markers and their active antigens in the involved tissues of patients with severe acute respiratory syndrome (SARS).

METHODS

Specimens of the lungs, spleens and lymph nodes were obtained from autopsy of 3 SARS cases to investigate the expression of the immune cells and their activities with double immunohistochemical staining (DAB and AP) by using 14 immune cell markers and their active antigens.

RESULTS

A large quantity of proliferated macrophages could be observed in the lungs, spleens and lymph nodes of the SARS patients, some of which were positive for CD25 marker (active macrophages). In the lungs of the 3 patients, localized necrosis occurred where infiltration of CD45RO (+) T lymphocytes was observed, with only scarce Ki67 (+) T lymphocytes (active T lymphocytes) and B lymphocytes. In the lymph nodes, scattered T lymphocytes positive for Ki67 and CD45RO markers (active T lymphocytes) were seen, but the T lymphocytes subpopulations were obviously decreased, which was especially so with CD4+ and CD8+ T lymphocytes and NK cells.

CONCLUSION

Significantly enhanced activity of the macrophages occurs in SARS as the major reactive cells, but T lymphocyte subsets are obviously decreased, indicating the important roles of the macrophages and T lymphocytes in the pathogenesis of SARS.

[Clinical analysis of pediatric SARS cases in Beijing]

OBJECTIVE

To study clinical characteristics of pediatric SARS cases in Beijing.

METHODS

Eighteen pediatric cases with SARS diagnosed on admission were analyzed. The cases were admitted to Beijing Children's Hospital and Ditan Hospital (pediatric ward) from April 8 to May 12.

RESULTS

The 18 children aged 5 months to 15 years (10 male and 8 female) had epidemiologically linked findings. Fourteen cases had close contact with SARS patients. Four cases were living in the community where adult SARS patients were found. All the 18 patients but one presented with fever and cough. Most of them had high fever, 2 cases had bradycardia, 2 had diarrhea, and another 2 had tachypnea. Malaise and headache were noted only in 3 cases respectively which were much less frequently seen than in adult patients. Symptoms and signs of the children were much less severe and aggressive than adults cases. Thirteen children had chest radiographic consolidation. Of them, 9 cases had progressive changes after admission, then improved quickly. We did not find significant lower hemoglobin and platelet levels. Most patients had leukopenia and lymphopenia. Serologic test was performed for 15 cases and 8 were positive for SARS virus-IgG and 6 for IgM antibody. Of the 4 cases who had close contact with SARS adults and without chest radiograph abnormal findings, 3 were negative for SARS virus-antibodies. Part of the patients had temporary abnormality of myocardial enzyme and liver function. All these children finally had rapid improvement on chest radiograph. The patients were treated with antiviral agents and corticosteroid. Only two cases required oxygen therapy. No child needed assisted ventilation and no death, nor lung fibrosis occurred. After hospitalization, all patients were improved and discharged when this paper was being written. The average hospital stay of these patients was 14.6 days (6 - 22 days).

CONCLUSION

Compared with adults, pediatric SARS patients seemed to have their own clinical characteristics. The disease in children had lower severity and infectivity than that in adults. The mechanisms of the disease in children should be studied in well-designed clinical trials. Cases like the 4 children who had close contact with SARS adult patients but without chest radiographic changes deserve further studies with the help of more reliable and sensitive etiologic tests.