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[Immunological and biological characteristics of viral isolates of porcine reproductive and respiratory syndrome].

Described in the paper are study results of some immunobiological properties of 5 field isolates of the porcine reproductive and respiratory syndrome virus (PRRSV), obtained in Russia and Byelorussia in 1998-2001. According to the research work, the PRRSV isolates with different immunobiological properties have been circulating in the territories of Russia and Byelorussia. Three of the 4 examined virus isolates were found to be pathogenic and 1 avirulent to pigs.

Animals↗

[Cuban epidemic neuropathy. IV. The antigenic relationship of the viral isolates to the structures of the central nervous system. A possible etiopathogenic mechanism?].

Results which allow to state the existence of antigenic relationships between viruses isolated from the cerebrospinal fluid of patients presenting with epidemic neuropathy and structures of the human central nervous system are reported. These evidences were obtained by 2 different and independent ways: 1) by the double diffusion method in agarose, immunoblot analysis, and immunohistochemical analysis it was confirmed that antibodies induced by isolated viruses react with antigens of the central and peripheral nervous system, 2) serum obtained by the immunization of a rabbit with human brain extract neutralizes the same viruses as those neutralized by hyperimmune sera obtained by isolations. The possible role of viruses as mediators of an autoimmune process in the pathogenesis of the disease is discussed.

Animals↗

Molecular and phylogenetic analysis of haemagglutinin and neuraminidase sequences from recent human influenza type A (H3N2) viral isolates in Southern Greece.

Eighteen haemagglutinin (HA1) gene segments and eleven neuraminidase (NA) genes of human influenza type A (H3N2) viruses isolated from non-vaccinated individuals presenting severe influenza-like illness at peak influenza activity in Southern Greece during the surveillance period 1996-1999, were subjected to sequence and phylogenetic analyses following propagation in embryonated hen's eggs. The HA1 gene segment of the clinical isolates differed from the recent reference influenza type A (H3N2) vaccine strains in an Ile at residue 186, a Val at residue 194 and a Val at residue 226 for one, two and thirteen isolates of the 1996-1997 and 1996-1999 periods, respectively. The analogous differences in the NA gene were confined in an Asp to Asn substitution at residue 198 in one A/Wuhan/359/95 (H3N2)-like isolate of the 1996-1997 period, primarily. In addition, phylogenetic analysis revealed that an isolate of the 1997-1998 period was a recombinant with its HA1 gene segment being closely related to that of A/Wuhan/359/95-like viruses and its NA to viruses of the A/Sydney/5/97 (H3N2) lineage. These findings confirmed the profound genetic instability of influenza type A (H3N2) viruses and underscored the importance for periodic molecular surveys of HA and NA in the effective prevention and management of viral outbreaks. Most importantly, however, they contributed the first complete epidemiological material for influenza in Southern Greece, the archival nature of which constitutes valuable reference for future surveys.

Amino Acid Sequence↗

[Detection of nonpoliomyelitic enteroviruses in central nervous system infections in Poland in 1995-2000; viral isolation data].

The aim of this study was evaluation of enterovirus diagnosis based on isolation of the virus in cell culture from subjects with aseptic neuroinfection conducted in six Provincial Sanitary-Epidemiological Stations in 1995-2000 years. Available data from six Sanitary-Epidemiological Stations indicated that 1429 isolation of enteroviruses from fecal samples of those patients were performed. The most frequently isolated enterovirus serotype was echovirus type 30: 138/203 isolated enteroviruses, but also others enterovirus serotypes were isolated in a study period. In the years 1995 and 1996 the percentage of positive results of isolation was highest with the numbers of 31% and 28.27% respectively. The decrease in positive isolation results has been observed from 1997 year. Negative results of isolation come up to 90% of investigated cases. Only 1.5% of enterovirus isolation attempts finished successfully in 2002 year. The situation when percentage of positive results of isolation is on so low level, the natural alterations in a profile of enterovirus serotype infected population cannot be observed, and serological investigations can be conducted for enterovirus serotypes others than really circulating and causing infections in population.

Antibodies, Viral↗

Report on the first outbreaks of the porcine reproductive and respiratory syndrome (PRRS) in France. Diagnosis and viral isolation.

We describe the first known occurrence in France of the porcine reproductive and respiratory syndrome (PRRS), a new porcine disease that first appeared in Germany in November 1990. Outbreaks of the disease appeared in November 1991 in Brittany (France), with comparable clinical features to those observed in other countries, were definitively confirmed by a serological analysis from the affected animals using an immunoperoxidase monolayer assay with PRRS-virus infected alveolar macrophages. Furthermore, we report the isolation from one serum of a filtrable agent that, in view of its cytopathic effect for porcine alveolar macrophages and of the serologic reactivity of the infected cells, appears similar to the Lelystad virus that has been implicated in the etiology of the disease.

Animals↗

Comparative analysis: intracellular precursor polyproteins of baboon endogenous retroviruses and human viral isolate HL23V.

Intracellular precursor polyproteins of three baboon endogenous retrovirus (BaEV) isolates, m7, 455K, and BILN, were compared with the intracellular proteins of the type C human isolated HL23V by radioimmunoprecipitation, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and tryptic peptide analysis. Human and canine cells infected with m7-BaEV and canine thymus cells infected with BILN-BaEV were characterized by identical precursor polyproteins Pr85gag, Pr70-71gag, Pr65gag, and gPr85env. Canine cells infected with 455K-BaEV consistently showed a slightly different pattern of precursor polyproteins. These included Pr85gag, Pr70gag, Pr67gag, and gPR85env. By tryptic digest mapping of peptides containing [3H]leucine, m7-BaEV and 455K-BaEV were shown to be highly related. By comparison, mapping studies showed that BILN-BaEV was less highly related to m7-BaEV than ws 455K-BaEV. Differences in these related BaEV isolates presumably reflected virus-specific differential cleavage of core protein precursors or alterations in polyprotein primary structure or both. Chase-incubated cells infected with BaEV also contained a stable, p28-related polyprotein termed P72gag. This polyprotein migrated upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis slightly slower than the major core protein precursor Pr70-71gag and appeared to arise by posttranslational modification of Pr70-71gag. Immunoprecipitation of extracts of HL23V-infected cells with antisera to simian sarcoma-simian-associated virus proteins and BaEV proteins confirmed that these cells contained two unrelated viral components, one that was similar to m7-BaEV or BILN-BaEV and a second that was related to simian sarcoma-simian-associated virus. Tryptic digest mapping of BaEV and HL23V prcursor polyproteins suggested that the BaEV-like component of HL23V weas more closely related to m7-BaEV than to 455K-BaEV or BILN-BaEV.

Animals↗

Detection of B-tropic endogenous type-C virus in viral isolates originating from induced BALB/K-3T3 cells.

Isoelectric focusing (IEF) analysis of class I endogenous type-C virus induced by iododeoxyuridine treatment of BALB/K-3T3 cells revealed, in addition to the major variant of the p30 polypeptide, which has an isoelectric point of 6.1 (pI 6.1 isop30), a minor isop30 with a pI of 5.6. This value was also found for a prototype BALB/c B-tropic endogenous virus isolate. The pI 5.6 isop30 of the N-tropic isolate was amplified by long-term virus replication in B-type mouse cells, and comparative IEF and XC-assay data suggest that it may correspond to a B-tropic subpopulation which has not yet been detected in vitro in mouse cells of embryonic origin.

Animals↗

Comparative analyses of canine distemper viral isolates from clinical cases of canine distemper in vaccinated dogs.

Sequence and phylogenetic analyses of three isolates of canine distemper virus (CDV) isolated from three dogs with a vaccination history were compared with the same analyses of vaccine virus isolated from a vaccine used for dogs. The three dogs showed clinical signs of a recent major type of CD in Japan, including oculonasal discharge and diarrhea, and pathological findings including non-suppurative encephalitis, pneumonia, mild gastroenteritis and lymphoid depletion. Inclusion bodies were in the stomach without inflammation and encephalitis was without clinical signs. One of the highest titers of CDV in different organs of the three dogs was commonly systemic lymphatic organs, including the spleen, lymph nodes and tonsils. New isolates of CDV joined to the clades of the Asia 1 group that is far from the vaccine group. These results surely indicate that wild strains of CDV from dogs with a vaccination history were not reversed vaccine virus, and that the dogs showed characteristics of recent CD in Japan.

Amino Acid Sequence↗

Transmission of herpes-simplex virus type 1 in a nursery for the newborn. Identification of viral isolates by D.N.A. "fingerprinting".

The occurrence of herpes-simplex-virus type-1 infections in two newborn infants in a nursery within a one-month period suggested the possibility of transmission in the nursery. One infant may have been infected by his father, who had active herpes labialis at the time of the child's birth. The source of the second infant's infection was not apparent. Viruses isolated from the two infants were "fingerprinted" by cleaving the virus-specific D.N.A. with several restriction endonucleases and comparing the electrophoretic patterns. Isolates from the two infants were identical and differed from other isolates from epidemiologically unrelated cases. This observation confirmed the possibility of transmission of herpes-simplex virus type 1 in the nursery, but did not define the mode of transmission. Type-1 infections are serious in neonates: one of the infants died and an oesophageal stricture developed in the other. The "fingerprinting" technique provides a useful epidemiological technique for tracing the transmission of herpes virus infections.

Adult↗

In vitro cellular responsiveness in multiple sclerosis patients to a viral isolate from multiple sclerosis brain tissue and to other antigens.

The Clausen modification of the leukocyte migration test was used to test patients with multiple sclerosis, normal subjects, and patients with other neurologic diseases for cell-mediated immunity to 6/94 virus (a parainfluenza virus previously isolated from the brain tissue of a multiple sclerosis patient), c-RNA virus isolated from a tumor, and the nonviral antigens Candida and purified protein derivative. Leukocytes of multiple sclerosis patient showed significantly less mean inhibition of migration by the 6/94 virus (but not by the c-RNA virus, purified protein derivative, and Candida) than did the cells of normal controls and patients with other neurologic diseases. The relationship of these findings to previous observations in this area and to the pathogenesis of multiple sclerosis is discussed.

Antigens, Viral↗

Novel mutations in the respiratory syncytial virus G gene identified in viral isolates from a girl with severe combined immune deficiency treated with intravenous immune globulin.

BACKGROUND: Respiratory syncytial virus (RSV) can cause prolonged infections in individuals with compromised immunity. OBJECTIVES: To investigate whether RSV evolves during prolonged infection in an immunocompromised host. STUDY DESIGN: We sequenced the envalope glycoprotein genes of RSV obtained at three time points during a 59-day period from a 4-year-old female with severe combined immune deficiency (SCID) treated with intravenous immunoglobulin (IVIG). RESULTS: Sporadic silent mutations were found in the SH, G and F genes among three RSV samples collected at days 0, 19 and 59. Premature stop codons at amino acid positions 257 and 278 were present in the RSV G glycoprotein gene sequenced from each time point. None of the 48 RSV G sequences available on GenBank or any of 50 genetically diverse clinical isolates of RSV contained these mutations. These premature stop codon mutations occurred at the same positions of the G glycoprotein gene as those described in in vitro monoclonal-antibody resistant mutants reported elsewhere. CONCLUSION: Our patient was most likely infected with a single RSV strain that did not mutate during the study period. This strain contains unique mutations that may have previously evolved in this individual who had prolonged infection and was treated with monthly IVIG.

Amino Acid Sequence↗

Atypical hog cholera infection: viral isolation and clinical study of in utero transmission.

Sows in different stages of pregnancy were inoculated with a low-virulence hog cholera strain. Clinical signs of disease were not observed in the sows during pregnancy, but most of their pigs were splaylegged and had nervous disorders; perinatal mortality was high. A few pigs from sows that were inoculated during the 1st trimester of pregnancy survived and remained inapparent carriers of virus, without developing antibodies. Seemingly, these pigs were immunotolerant. Virus was transmitted from immunotolerant pigs to susceptible pigs by contact 5 weeks after farrowing, but not 3 months after farrowing, despite the persistence of the virus at a high concentration in the blood and in the organs of the immunotolerant pigs.

Animals↗

Diagnosis of herpes simplex virus by direct immunofluorescence and viral isolation from samples of external genital lesions in a high-prevalence population.

One hundred thirty specimens from 108 consecutive patients with a history of recurrent genital ulcerations were used in a study comparing herpes simplex virus (HSV) isolation with a direct fluorescent-antibody (DFA) technique using mouse monoclonal antibodies. HSV was isolated from 70% of vesicular lesions, 67% of pustular lesions, 32% of ulcerative lesions, and 17% of crusted lesions, whereas the DFA technique detected HSV antigen in 87, 67, 30, and 10% of lesions in similar stages, respectively. When both methods were used, HSV was identified in 97, 79, 45, and 17% of vesicles, pustules, ulcers, and crusted lesions, respectively. The overall sensitivity and specificity of the DFA technique in comparison with virus isolation (VI) were 74 and 85%, respectively. Of the 17 patients from whom DFA-positive, VI-negative samples were obtained, HSV was subsequently isolated from a genital lesion in 14, suggesting that they were not DFA false-positives. Similarly, of the 46 patients whose initial lesion samples were DFA and VI negative, 37 (80%) had HSV identified from subsequent genital lesions during follow-up. Thus, a single sample for VI or DFA testing from a recurrent genital lesion had a sensitivity of only 53 and 51%, respectively. Combining the DFA technique and VI increased the sensitivity of laboratory diagnosis of a single recurrent episode of genital HSV; however, repetitive laboratory testing was often required to confirm the diagnosis of recurrent genital HSV infection.

Antibodies, Monoclonal↗

Diagnosis of cytomegalovirus pneumonitis on bronchoalveolar lavage fluid: comparison of cytology, immunofluorescence, and in situ hybridization with viral isolation.

Forty-three bronchoalveolar lavage (BAL) specimens from 40 immunocompromised patients were studied for the presence of cytomegalovirus (CMV) by rapid diagnostic methods. DNA in situ hybridization, cytology, and immunofluorescence were compared to conventional cell culture. Eleven (25%) of the 43 BAL samples grew CMV in culture. In situ hybridization detected 6 of these 11 for sensitivity, specificity, and predictive values of positive and negative of 55%, 94%, 75%, and 86%, respectively. Cytology had a sensitivity of 73% and specificity of 100%. Six Papanicolaou-stained cytospins were screened cytologically versus one hybridization cytospin, and the higher sensitivity of cytology may reflect this extensive sampling. The immunofluorescent method had a sensitivity equal to that of cytology (73%): however, the specificity (72%) was significantly less than that of either the probe or cytology. These data suggest that although in situ hybridization can be a rapid, useful method for detecting CMV in BAL specimens, cytology appears to be a more sensitive method.

Bronchoalveolar Lavage Fluid↗

Genotypic resistance tests for the management of the HIV-infected patient with non-B viral isolates.

Witness for the prosecution: The dominating HIV-1 subtype in Europe and in the USA is the B subtype, but the prevalence of circulating recombinant forms and non-B subtypes (nBS) in Europe has increased. HIV-1 group O strains are spontaneously resistant to non-nucleoside analogue reverse transcriptase inhibitors (NNRTI) and little is known about the antiretroviral (ARV) drug susceptibility of nBS clinical isolates. Controlled randomized trials showing a clinical benefit of a treatment guided by HIV-1 resistance testing at virological failure have been conducted on subtype B. Thus, the result cannot be simply extended to nBS. In nBS, the frequency or amplification failure is increased, but retesting failed samples with an alternative set of polymerase chain reaction primers improves the success of amplification. The major problem is the reliability of genotypic resistance tests (GRT) owing to misinterpretation of the obtained amino acid mutations, the background sequence in nBS being different from the standard used in the commercial kits or in the web-based HIV-1 resistance interpretation tools. At the moment, no nBS database is available to help in the interpretation of the protease and RT sequence results. Furthermore, the mutational pattern of specific ARV drugs may be different, in particular with subtype C and G. In conclusion, in patients with nBS the indication to for at virological failure may exists, even in the absence of clinical evidence, but the results have to be interpreted by experts with particular caution. Witness for the defence: The extensive variability of HIV-1 has a potential impact on epidemiology, diagnosis, therapy and the prevention of infection. Nine different major subtypes of group M (A-D, F-H, J and K) circulate to varying extents in populations around the globe together with the circulating recombinant forms (CRF) owing to intersubtype recombinations. Although viruses belonging to the HIV-1 B clade are still predominant in Europe, the USA and Australia, an increasing prevalence of non-clade B subtypes and CRF has been reported by several surveys in previously homogeneous clade B countries. As current ARV have been designed using subtype B strains and resistance mutations have been characterized on this subtype, the increasing global spread of HIV subtypes highlights the need to determine the activity of anti-HIV drugs against subtypes or CRF other than subtype B.

Anti-HIV Agents↗

Viral isolates derived from simian varicella epizootics are genetically related but are distinct from other primate herpesviruses.

Epizootics of a natural varicella-like disease occur in populations of nonhuman primates. Several primate herpesviruses have been isolated from these epizootics, but the relatedness of these isolates to each other is not well-defined. In this study, we demonstrated that the restriction endonuclease (REn) profiles of four epidemiologically distinct isolates were similar, although not identical, indicating that simian varicella epizootics are caused by various strains of simian varicella virus (SVV). The genetic variation among the isolates did not map to a specific region of the SVV genome and REn differences were detected within the SVV DNA long component and the inverted repeat region. Southern blot hybridization demonstrated that SVV is more closely related to varicella-zoster virus than to other primate herpesviruses. The study indicates that the current herpesvirus classification scheme should be changed to include SVV as a single taxonomic group within the Varicellovirus genus of alphaherpesviruses. In addition, REn profiles of SVV isolates, derived from primary and secondary episodes of simian varicella in the same monkey, were identical, providing evidence for SVV reactivation in a latently infected monkey.

Animals↗