RESUMO
Noroviruses and Sapoviruses, classified in the Caliciviridae family, are small positive-stranded RNA viruses, considered nowadays the leading cause of acute gastroenteritis globally in both children and adults. Although most noroviruses have been associated with gastrointestinal disease in humans, almost 50 years after its discovery, there is still a lack of comprehensive evidence regarding its biology and pathogenesis mainly because they can be neither conveniently grown in cultured cells nor propagated in animal models. However, other members of this family such as Feline calicivirus (FCV), Murine norovirus (MNV), Rabbit hemorrhagic disease virus (RHDV), and Porcine sapovirus (PS), from which there are accessible propagation systems, have been useful to study the calicivirus replication strategies. Using cell cultures and animal models, many of the functions of the viral proteins in the viral replication cycles have been well-characterized. Moreover, evidence of the role of viral proteins from different members of the family in the establishment of infection has been generated and the mechanism of their immunopathogenesis begins to be understood. In this review, we discuss different aspects of how caliciviruses are implicated in membrane rearrangements, apoptosis, and evasion of the immune responses, highlighting some of the pathogenic mechanisms triggered by different members of the Caliciviridae family.
Assuntos
Infecções por Caliciviridae/imunologia , Infecções por Caliciviridae/virologia , Caliciviridae/imunologia , Interações Hospedeiro-Patógeno/imunologia , Imunidade , Imunomodulação , Imunidade Adaptativa , Animais , Peptídeos Catiônicos Antimicrobianos , Apoptose , Caliciviridae/genética , Infecções por Caliciviridae/metabolismo , Membrana Celular/metabolismo , Membrana Celular/virologia , Efeito Citopatogênico Viral , Suscetibilidade a Doenças , Regulação Viral da Expressão Gênica , Genoma Viral , Humanos , Evasão da Resposta Imune , Imunidade Inata , Interações Microbianas , Microbiota , Replicação ViralRESUMO
To define the role of human caliciviruses (HuCVs) in severe childhood gastroenteritis, fecal and paired serum samples from 233 Peruvian children hospitalized with gastroenteritis (case patients) and fecal samples from 248 control subjects were evaluated. Overall, 128 case patients (55%) demonstrated HuCV infection by either fecal (n=81 [35%]) or serological (n=96 [41%]) testing. HuCVs were more prevalent in fecal samples from case patients than those from control subjects (35% vs. 13%; P<.001). HuCV infection was more prevalent among case patients without another pathogen than in those who had a coinfecting pathogen (77% [40/52] vs. 49% [88/181]; P<.001). HuCVs appear to be an important cause of gastroenteritis in Peruvian children.
Assuntos
Infecções por Caliciviridae/virologia , Caliciviridae/isolamento & purificação , Gastroenterite/virologia , Anticorpos Antivirais/sangue , Caliciviridae/genética , Caliciviridae/imunologia , Estudos de Casos e Controles , Pré-Escolar , Fezes/virologia , Feminino , Humanos , Técnicas Imunoenzimáticas , Lactente , Recém-Nascido , Masculino , Peru , RNA Viral/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Soro/virologiaRESUMO
A cDNA obtained from Grimsby virus (GRV), a Norwalk-like virus, purified from a stool sample of a symptomatic adult associated with a gastroenteritis outbreak in the United Kingdom, was used to obtain the complete nucleotide sequence of the second open reading frame (ORF2). The ORF2 sequence of GRV predicts a capsid of 539 amino acids (aa) which exhibits aa identities of 96% to Lordsdale virus, 67% to Mexico virus (MXV), and 43% to Norwalk virus (NV). The GRV capsid protein was expressed in insects cells by using a recombinant baculovirus, and the resulting virus-like particles (VLPs) possessed a protein with an apparent molecular weight of 58,000. Hyperimmune antisera raised against purified GRV, MXV, and NV VLPs were tested in an indirect enzyme-linked immunosorbent assay (ELISA) against GRV, NV, and MXV VLPs, revealing that GRV is antigenically distinct from both NV and MXV. The antigenic specificity of the GRV-hyperimmune antiserum was confirmed in an antigen capture ELISA using GRV-, NV-, or MXV-containing fecal specimens. The expression of the GRV capsid protein has, for the first time, allowed the antigenic comparison of three distinct recombinant Norwalk-like viruses.
Assuntos
Antígenos Virais/genética , Caliciviridae/genética , Caliciviridae/imunologia , Vírus Norwalk/genética , Vírus Norwalk/imunologia , Adulto , Sequência de Aminoácidos , Anticorpos Antivirais , Antígenos Virais/química , Caliciviridae/crescimento & desenvolvimento , Infecções por Caliciviridae/virologia , Capsídeo/química , Capsídeo/genética , Capsídeo/imunologia , DNA Complementar/genética , DNA Complementar/isolamento & purificação , DNA Viral/genética , DNA Viral/isolamento & purificação , Gastroenterite/virologia , Expressão Gênica , Genes Virais , Humanos , Microscopia Eletrônica , Dados de Sequência Molecular , Peso Molecular , Vírus Norwalk/crescimento & desenvolvimento , Fases de Leitura Aberta , Homologia de Sequência de Aminoácidos , Especificidade da EspécieRESUMO
Small round-structured viruses (SRSVs) or Norwalk-like viruses have been implicated as an important causative agent of gastroenteritis outbreaks. We used the relatively newly developed recombinant enzyme immunoassays (EIAs) to determine the seroprevalence of Norwalk virus (NV) and Mexico virus (MxV) in a family-based cohort and an antenatal clinic cohort at Ga-Rankuwa Hospital, Ga-Rankuwa, South Africa. High prevalences (96 to 99%) of anti-NV and anti-MxV antibodies were detected in both cohorts. We also investigated the pattern of antibody acquisition in a cohort of infants and young children without gastroenteritis and found that by 48 months of age all children had acquired adult antibody levels to both these viruses. Lastly, we tested 276 stool specimens collected from infants and young children with gastroenteritis for the presence of NV or MxV antigen by recombinant EIAs to each virus, by electron microscopy (EM), and by reverse transcription (RT)-PCR. NV and MxV antigens were present in 1.8 and 4.3% of the stool specimens, respectively, by the recombinant EIAs; 9.2% were positive for SRSVs by EM, and 25% of these SRSVs gave a positive result by RT-PCR for primer pair 35-36 directed to a region of the RNA-dependent RNA polymerase gene. The seroprevalence studies indicate a high level of exposure to these viruses in both children and adults. Although the viral antigens are not highly prevalent in diarrheal stools, it was determined by the two assays for NV and MxV that children are, nevertheless, infected early in life.
Assuntos
Anticorpos Antivirais/análise , Infecções por Caliciviridae/epidemiologia , Caliciviridae/imunologia , Gastroenterite/virologia , Vírus Norwalk/imunologia , Adolescente , Adulto , Idoso , Sequência de Aminoácidos , Antígenos Virais/isolamento & purificação , Caliciviridae/genética , Caliciviridae/isolamento & purificação , Infecções por Caliciviridae/imunologia , Capsídeo/genética , Capsídeo/imunologia , Criança , Pré-Escolar , Surtos de Doenças , Fezes/virologia , Feminino , Gastroenterite/epidemiologia , Humanos , Técnicas Imunoenzimáticas , Masculino , Microscopia Eletrônica , Pessoa de Meia-Idade , Dados de Sequência Molecular , Vírus Norwalk/genética , Vírus Norwalk/isolamento & purificação , Filogenia , Reação em Cadeia da Polimerase , Prevalência , RNA Polimerase Dependente de RNA/genética , Proteínas Recombinantes/imunologia , Sensibilidade e Especificidade , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Estudos Soroepidemiológicos , África do Sul/epidemiologiaRESUMO
The use of a recently developed EIA using antisera raised against purified baculovirus expressed recombinant Mexico virus (rMx) capsid protein is described for screening for human calicivirus in stools. The results show that MX-like viruses have been circulating in the UK periodically since 1983 and were an occasional cause of sporadic cases of diarrhoea in infants and outbreaks of infection among elderly patients in hospitals and old people's homes. Further evidence is presented that some strains of caliciviruses with characteristic surface morphology (HuCVs) and some with an indistinct appearance, small round structured viruses (SRSVs) are antigenically related to MxV. Tests on SRSVs from four unrelated outbreaks typed as UK3 failed to react in the Mx EIA or recombinant Norwalk virus (rNV) EIA. A 2-month survey of 206 children treated in two London hospitals for diarrhoea showed that only one was positive for MxV, a child known to be infected with HIV-1. None of the samples reacted in the rNV EIA.
Assuntos
Infecções por Caliciviridae/virologia , Caliciviridae/isolamento & purificação , Diarreia/virologia , Adulto , Antígenos Virais/imunologia , Caliciviridae/imunologia , Caliciviridae/ultraestrutura , Infecções por Caliciviridae/epidemiologia , Infecções por Caliciviridae/imunologia , Capsídeo/imunologia , Criança , DNA Viral/análise , Diarreia/epidemiologia , Diarreia/imunologia , Surtos de Doenças , Humanos , México , Reino Unido/epidemiologiaRESUMO
The use of an enzyme immunoassay (EIA) employing a baculovirus-expressed recombinant human calicivirus (Mexico virus, MxV) for the detection of IgG-specific antibodies is described. MxV appeared to be related antigenically to a strain of small round structured virus, SRSV/UK4/Leeds/91, which had previously been shown by solid phase immune electron microscopy (SPIEM) to be related to Snow Mountain agent (SMA). One other outbreak which occurred in San Anita, USA in 1980 and was due to consumption of contaminated water was caused by a virus antigenically related to MxV. Volunteers and patients who developed significant IgG responses to rMxV showed anamnestic IgG responses (2 to 4-fold) in the recombinant Norwalk virus (rNV) IgG assay. Patients and volunteers who were known to have been infected with several other strains of calicivirus/small round spherical viruses (SRSV) including NV and SRSV UK3 showed no significant antibody response to rMxV in the EIA. A seroepidemiological survey of sera from 338 children in London showed that infection with MxV occurred earlier in life than NV. Primary infections with MxV were common after the age of 6 months. Over 70% of children had evidence of infection by the ages of 2 years, whereas only 12% of these children had been infected with NV. High concentrations of maternal antibody were present during the first month of life which was detected in 96% of the neonates. The results suggest that the high sensitivity of the EIA may be detecting maternal antibody throughout the first 8 months of life.