Construction of gag, pol, and env specific riboprobes for confirmation of HIV-1 specific polymerase chain reaction products

Conserved regions of the gag, pol, and env genes of HIV-1 pBH10 DNA (gag nucleotides(nt)1508-1652, pol nt 2811-3118, env nt 7792-7934; Ratner et al., 1985) were amplified by the polymerase chain reaction (PCR) using oligonucleotides complementary to the termini of these regions as primers. Primer areas of the amplified DNA were then removed by digestion with restriction endonucleases, and the internal fragments purified and cloned in both orientations into the 'riboprobe' transcription vector pGEM-5Z. Riboprobes made from these plasmids did detect the specific sequences of pBH10 DNA and of HIV-1 DNA amplified by PCR from clinical material. The riboprobes will be useful to confirm the specificity of PCR-amplified fragments of lymphocyte DNA obtained from infants of HIV-infected mothers and from high risk, but seronegative contacts of HIV-1 infected individuals.

Detection of immunoglobulin M (IgM), IgA, and IgG Norwalk virus-specific antibodies by indirect enzyme-linked immunosorbent assay with baculovirus-expressed Norwalk virus capsid antigen in adult volunteers challenged with Norwalk virus

Pre- and postexposure sera collected from 17 adult volunteers challenged with Norwalk virus as described previously (D. Y. Graham, X. Jiang, T. Tanaka, A. Opekun, P. Madore, and M. K. Estes, J. Infect. Dis. 170:34-43, 1994) were examined for Norwalk virus-specific immunoglobulin M (IgM), IgA, and IgG by indirect enzyme-linked immunosorbent assays with recombinant Norwalk virus antigen bound to the solid phase. Sixteen of the 17 volunteers had evidence of past infection, all presenting with preexisting IgG antibody of high avidity; only one volunteer had no evidence of previous infection. Virus infection was detected in 14 of the 16 volunteers with evidence of past infection, and 9 of the infected volunteers had symptomatic illness. A significant rise in both virus-specific IgA and IgG titers was detected after challenge in all of the volunteers who became ill. Five of the asymptomatic volunteers who were infected had rising titers of virus-specific IgG, but only two of the five had a concomitant rise in their virus-specific IgA antibody titers. Antibody rises were detectable in eight of nine ill volunteers 8 to 11 days after challenge but in the asymptomatic volunteers only after more than 15 days had elapsed. Virus-specific IgM was detected after challenge in all 14 infected volunteers. Between symptomatic and asymptomatic volunteers there were no significant differences in titers of virus-specific IgG and IgA in serum before challenge; however, there were significantly higher titers in symptomatic volunteers between 8 and > 90 days after challenge for virus-specific IgG and 8 and 24 days after challenge for virus-specific IgA.

Human parvovirus B19 serology with recombinant VP1 and VP2 antigens: diagnosis of acute infections by detecting B19-specific IgM and IgA antibodies

BACKGROUND

The availability of immunoassays for the laboratory diagnosis of human parvovirus B19 (B19) infection, which is commonly associated with erythema infectiosum in children and arthropathy and arthralgia in adults has been hampered by the lack of native B19 antigen. The production of abundant supplies of recombinant (r) B19 proteins, through the cloning of the B19 genome into expression vectors, has led to a proliferation of assays for detecting B19-specific antibodies.

OBJECTIVES

This study was undertaken to evaluate serological assays for detecting B19-specific IgM and IgA antibodies using rVP1 and rVP2 B19 viral coat proteins. Their suitability in the diagnosis of acute B19 infections and the incidence of non-specific reactivity were determined.

STUDY DESIGN

A panel of sera consisting of B19-specific IgM-positive and -negative samples was tested for B19-specific IgM and IgA antibodies in an indirect IFA using rVP1 antigen. These samples and a further panel collected from patients with other virus infections and samples containing rheumatoid factor were tested for B19-specific IgM in an antibody-capture ELISA and an indirect ELISA, both of which utilized rVP2 antigen.

RESULTS

Data from the two ELISAs using rVP2 antigen and the IFA with rVP1 antigen all showed significant correlation (P >/= 0.001) with a reference RIA using native B19 antigen. Non-specific reactions were observed with Paul-Bunnell-positive and rubella virus-specific IgM antibody-positive sera in the ELISAs but not in the IFA. B19-specific IgA antibodies were detected in all sera containing B19-specific IgM antibodies but were also found in a small number of sera collected from healthy blood donors with no history of recent B19 infection.

CONCLUSION

This study demonstrates the usefulness of assays employing rVP1 and rVP2 B19 antigens for detecting B19-specific antibodies. The use of IgM-specific ELISAs allows the processing of large numbers of samples and the absence of non-specific reactivity in the IFA may indicate a role for this assay as a confirmatory test.

Sequence analysis of two porcine rotaviruses differing in growth in vitro and in pathogenicity: distinct VP4 sequences and conservation of NS53, VP6 and VP7 genes

The VP4, VP7, NS53 and VP6 genes of two porcine rotavirus variants which differ in their in vitro growth properties and pathogenicity have been cloned and sequenced. The VP4 genes show only 67.2% nucleic acid and 70.6% amino acid identity. The VP4 gene of one variant (4S) is closely related to that of the bovine UK rotavirus strain, whereas the VP4 gene of the other variant (4F) is only distantly related to known VP4 genes and is likely to represent a new P serotype. In contrast the NS53 (VP5), VP6 and VP7 genes of the 4F and 4S variants show greater than 99% nucleotide and amino acid identity, indicating that the two viruses are genetically related by a reassortment event. The implications for the role of VP4 in the determination of in vitro growth characteristics and pathogenicity are discussed.

Hepatitis C virus infections in transplant patients: serological and virological investigations

Hepatitis C virus (HCV) is transmitted by organs of HCV antibody-positive donors to transplant recipients. This study investigated the serological and virological responses of 14 initially HCV antibody-negative transplant patients who received organs from four HCV antibody-positive donors (A-D) (before donor screening for HCV infection was introduced in 1991). Second generation HCV enzyme immunoassay (Abbott HCV EIA) was used to detect anti-HCV antibody. Recombinant immunoblot (RIBA-2; Chiron Corporation) and Wellcozyme Western blot (Wwb) assays were compared as confirmatory assays of positive EIA results. Reverse transcription (RT) followed by "nested" polymerase chain reaction (PCR) was performed to detect viral RNA. HCV RNA was only found in the sera of donors B and C, however, transplantation of organs from all donors resulted in infection of all recipients. HCV RNA was found in recipient sera within 30 days after transplant and remained detectable throughout the period of sampling. An anti-HCV antibody response was found in only 6 (of the 14) recipients and only after 300 days. Much longer periods passed before detection of HCV antibody in six recipients. For detection of HCV infection in transplant recipients it is essential that testing for HCV RNA by RT-PCR is carried out.

Molecular epidemiology of human rotaviruses in Manipur: genome analysis of rotaviruses of long electropherotype and subgroup I

In 1987/88 a winter outbreak of infantile gastroenteritis occurred in Manipur, India which was mainly due to rotaviruses of long electropherotype and subgroup (SG) I. The VP7 gene of one of these viruses (M48) has been cloned and sequenced. It was found to be very closely related to the VP7 genes of the G2 serotype human rotaviruses RV-5 and S2. Follow-up epidemiology of this event in Manipur during 1989-1992 yielded mainly rotaviruses of more conventional characteristics (94 isolates of SG II and long electropherotype, and 90 isolates of SG I and short electropherotype), but also 6 isolates of SG I with long electropherotype, indicating that these viruses continue to circulate in the Manipur community. One isolate of short electropherotype was of subgroup II, and one long electropherotype isolate reacted with the group A but not with either the subgroup I or subgroup II monoclonal antibodies.

Sequence diversity of small, round-structured viruses in the Norwalk virus group

We have determined the nucleotide sequences of a highly conserved region of the RNA-dependent RNA polymerase of the prototype Snow Mountain agent (SMA) and of four other small, round-structured viruses (antigenically Norwalk virus [NV]-like or SMA-like) following reverse transcription-PCR amplification of viral RNA obtained from human stools. The stool samples were either from volunteers administered SMA or from sporadic cases and outbreaks of gastroenteritis that occurred in Japan and the United Kingdom between 1984 and 1992. The GLPSG and YGDD RNA polymerase motifs were in the proper locations in the sequences of the five SRSVs, but each sequence was distinct from the 8FIIa prototype NV sequence and from each other. Analysis of the sequences and reactivities in a new NV antigen enzyme-linked immunosorbent assay showed that the five viruses could be divided into two groups (serogroups) with NV and SMA, respectively, being the prototypes. The sequences of the capsid region and a nonstructural region (2C) were determined from one strain from each group. One virus (SRSV-KY-89/89/J), isolated in Japan and antigenically similar to the prototype NV (isolated 21 years earlier in Ohio), showed a remarkable level of sequence similarity to NV. KY-89 and the 8FIIa NV showed 87.2% nucleotide similarity over 2,516 continuous nucleotides amounting to 96 to 98.9% amino acid similarity in three distinct domains in two open reading frames. Between the prototype SMA and NV, the polymerase region showed 63% nucleotide and 59% amino acid similarity, respectively. Two other antigenically SMA-like isolates (SRSV-925/92/UK and SRSV-OTH-25/89/J), from the United Kingdom and Japan, showed 80% nucleotide and 88 to 92% amino acid similarity in the polymerase region to the prototype SMA isolated 16 and 13 years earlier in the United States. The capsid region of the antigenically SMA-like OTH-25 virus showed 53% nucleotide and 65% amino acid similarity to the prototype NV capsid region. Domains of sequence diversity and conversation were identified within the capsid protein of these two distinct prototype serotypes of virus. These results indicate that NV-like and SMA-like agents are still circulating, and sequence comparisons will be useful to identify and classify distinct viruses in the NV group.

Temporal correlation between a single amino acid change in the VP4 of a porcine rotavirus and a marked change in pathogenicity

We previously described a marked increase in the pathogenicity of a cell culture grown porcine rotavirus, PRV 4F, during serial passage in gnotobiotic piglets (Bridger et al., 1992). Here we report close temporal correlation between this change in pathogenicity and an amino acid change within a highly conserved hydrophobic domain of VP4 at position 469. Cell culture grown PRV 4F is unique in having a hydrophilic residue, glutamine, at amino acid 469; all previously sequenced VP4s have hydrophobic leucine or phenylalanine residues at the corresponding position. The detection of a point mutation causing a deduced amino acid change from glutamine to leucine at amino acid 469 of PRV 4F VP4 in virus obtained from one piglet at the second serial passage correlated exactly with the emergence of viral pathogenicity. However, given the multifactorial nature of virus pathogenicity, genetic studies are required to ascertain the degree to which this mutation is responsible for the observed change in pathogenicity.

Construction of gag, pol, and env specific riboprobes for confirmation of HIV-1 specific polymerase chain reaction products

Conserved regions of the gag, pol, and env genes of HIV-1 pBH10 DNA (gag nucleotides(nt)1520-1665, pol nt 2326-2663, env nt 7192-7333; Ratner et al., 1985) were amplified by the polymerase chain reaction (PCR) using oligonucleotides complementary to the termini of these regions as primers. Primer areas of the amplified DNA were then removed by digestion with restriction endonucleases, and the internal fragments purified and cloned in both orientations into the 'riboprobe' transcription vector pGEM-5Z. Riboprobes made from these plasmids did detect the specific sequences of pBH10 DNA and of HIV-1 DNA amplified by PCR from clinical material. The riboprobes will be useful to confirm the specificity of PCR-amplified fragments of lymphocyte DNA obtained from infants of HIV-infected mothers and from high risk, but seronegative contacts of HIV-1-infected individuals.

Genomic variation of human immunodeficiency virus type 1 (HIV-1): molecular analyses of HIV-1 in sequential blood samples and various organs obtained at autopsy

Length polymorphisms and partial nucleotide sequences were determined for the hypervariable regions, V1 to V5, of the human immunodeficiency virus type 1 (HIV-1) env gene obtained from proviral DNA of sequential peripheral blood samples, from viral RNA in plasma, and from proviral DNA obtained from different organs of individuals at autopsy. The lengths of several env regions of HIV-1 proviral DNA differed markedly when obtained from different organs of an individual. Nucleotide sequences of the hypervariable V3 region of HIV-1 obtained from different organs of one patient demonstrated distinct viral variants. Most proviral DNA sequences found in organs were also present in viral RNA obtained from plasma. The majority of HIV-1 V3 variants present in the lymph tissue could be found in the plasma viral population obtained at autopsy and in the sequential blood samples obtained before death, but were absent from the cardiac blood provirus population obtained at autopsy. However, sequence variants found in the brain proviral DNA were not detected in either plasma or the sequential blood samples. Sequence differences were observed at the apex of the V3 loop between HIV-1 variants present in sequential blood samples and in blood lymphocytes and nervous tissue, lymph tissue and plasma obtained post-mortem. The potential effect of lymph tissue on the long-term persistence of different viral variants is discussed. Virus obtained from the two sequential blood samples produced syncytia in primary cultures and was easily transmitted to the continuous JM cell line. Consensus (majority) V3 loop sequences determined for the adapted viruses demonstrated that some, but not all, sequences were represented within the in vivo viral population.

Rearrangement of the VP6 gene of a group A rotavirus in combination with a point mutation affecting trimer stability

A group A rotavirus isolated from a lamb with diarrhea in Qinhai province, China, was serially passaged in fetal calf kidney cells. In passage 96, rearrangements of RNA segments 5 and 6 of the viral genome were found. Here we report the nucleotide and predicted amino acid sequences of normal and rearranged RNA 6, coding for the major inner capsid protein VP6. In comparison with the normal gene (N6), the rearranged RNA 6 (R6) contained the normal open reading frame followed by a 473-nucleotide (nt) duplication of the gene beginning 23 nt after the termination codon. The duplicated region starts at nt 768 and runs through to the 3' end of the gene. In accordance with the nucleotide sequence of the rearranged RNA 6, a normal-length VP6 product was found in cells infected with the mutant. However, a single-amino-acid change from proline to glutamine at position 309 slightly affected the electrophoretic mobility of the VP6 monomer of the R6 mutant and reduced the stability of VP6 trimers on gels and at low pH values compared with the normal gene product. The degree of relatedness of VP6 of the Chinese lamb rotavirus Lp14 to those of other group A rotaviruses was determined.

Complete sequence conservation of the human T cell leukaemia virus type 1 tax gene within a family cluster showing different pathologies

We have amplified, through PCR, the full-length tax gene of human T cell leukaemia virus type 1 (HTLV-1) derived from proviral DNA of peripheral blood lymphocytes of five first degree relatives of Afro-Caribbean origin. One patient (the father) had adult T cell leukaemia (ATL), one (the mother) tropical spastic paraparesis (TSP), and three (children) were healthy asymptomatic carriers. All five family members had identical tax nucleotide sequences as determined by direct sequencing of PCR products. This sequence was compared with tax gene sequences of an unrelated TSP patient of Afro-Caribbean origin, and of C8166 cells, and found to have one and seven nucleotide differences, respectively. At the amino acid level these three sequences differed from the HTLV-1 prototype Japanese strain (ATK-1). All sequence changes were clustered towards the 3' end of the gene. These data demonstrate the complete conservation of an HTLV-1 gene following, presumably, horizontal and vertical transmission of the virus. Clones of this gene showed more sequence variation within the TSP patient than the ATL patient, mostly consisting of point mutations; there was no conservation of mutations between the two individuals. These mutations occurred only in individual clones of the ATL patient whereas those of the TSP patient were found to be repeated in different clones. A tax-specific cytotoxic T lymphocyte response was observed in two asymptomatic carriers with low antibody titres, whereas none was detected in an individual with a high antibody level. No tax-specific sequence was identified which may have contributed to the apparently high degree of transmission from mother to children (three of five children tested) nor account for the differences between disease symptoms in the parents.

Nucleotide sequences of the VP4 and VP7 genes of a Chinese lamb rotavirus: evidence for a new P type in a G10 type virus

The VP7 and VP4 genes of a group A rotavirus (Lp14) isolated from a lamb with diarrhea in Qinhai province, China, in 1981 were reverse transcribed, amplified by PCR, cloned, and sequenced. The virus was found to possess a VP7 gene, classifying it as a G10 type, and a VP4 gene which showed only limited homology with any other known VP4 gene, suggesting its classification as a new P type and providing further evidence for the vast diversity of group A rotaviruses.

Genomic concatemerization/deletion in rotaviruses: a new mechanism for generating rapid genetic change of potential epidemiological importance

Three variants of group A rotavirus with large changes in their gene 5 structures have been analyzed at the molecular level. The first of these, P9 delta 5, was obtained during plaque purification undertaken as part of the biological cloning of a field isolate of virus. The gene 5 homolog in this isolate migrated just ahead of the normal segment 6 RNA, giving an estimated size of 1,300 bp. Molecular cloning and sequencing of this homolog revealed it to have a single 308-bp deletion in the center of the normal gene 5 sequence extending between nucleotides 460 and 768 of the normal gene sequence. This deletion caused a frameshift in the gene such that a stop codon was encountered 8 amino acids downstream of the deletion point, giving a predicted size for the protein product of this gene of 150 amino acids compared with the 490 amino acids of its normal-size counterpart. Attempts to detect this shortened protein in virus-infected cells were not successful, indicating that it was much less stable than the full-length protein and/or had suffered a large change in its antigenicity. The second two variants, brvA and brvE, were generated in an earlier study following the high-multiplicity passage of the UKtc strain of bovine rotavirus. Polyacrylamide gel electrophoresis analysis of these nondefective variants showed that brvA had a gene 5 homolog approximately equal in size to the normal RNA segment 2 (approximately 2,700 bp) and that brvE had a size of approximately 2,300 bp. Both variants showed changes in their gene 5 protein products, with brvA mimicking P9 delta 5 in failing to produce a detectable product whereas brvE produced a new virus-specific protein approximately 80 kDa in size. Full-length cDNA clones of the brvE gene 5 homolog were isolated, and analysis of their structure revealed a head-to-tail concatemerization of the normal gene 5 sequence with the first copy of the concatemer covering nucleotides 1 to 808 and the second covering nucleotides 92 to 1579, giving a total length of 2,296 bp. Sequencing across the junction region of the two copies of the gene showed that they were joined in frame to give a predicted combined open reading frame of 728 amino acids with the amino-terminal region consisting of amino acids 1 to 258 fused at the carboxy terminus to amino acids 21 to 490.(ABSTRACT TRUNCATED AT 400 WORDS)

A large Q fever outbreak in the West Midlands: clinical aspects

In the spring of 1989 the largest outbreak of acute Q fever recorded in the United Kingdom occurred in Solihull and surrounding areas of the West Midlands. The diagnosis was confirmed in 147 people, mainly males of working age. Windborne spread from farmland to the south of the urban area was the most likely route of infection. Fever was the commonest symptom, seen in 101/102 (99%) cases, followed by weight loss reported by 83/101 (82%). Headache, often severe, was experienced by 69/101 (68%). The commonest respiratory symptom was breathlessness, 65/102 (64%), followed by cough, 52/102 (51%), and chest pain, 46/102 (45%). Neurological features, seen in 23% of cases, were more prominent in this outbreak than is commonly recognized. Persisting ill health 6 months following the acute episode not due to chronic Q fever was also a prominent feature of this largely urban outbreak.

Detection of human parvovirus B19-specific IgM and IgG antibodies using a recombinant viral VP1 antigen expressed in insect cells and estimation of time of infection by testing for antibody avidity

Sera from patients with symptoms of recent human parvovirus B19 (B19) infection were tested for B19-specific IgM in an immunofluorescence assay (IFA) using insect cells expressing B19 recombinant VP1 coat protein as an antigen. A highly significant correlation (P < 0.001) was found between titres obtained in the IgM IFA and the units obtained in an IgM antibody-capture RIA using plasma derived native B19 antigen. An IgG IFA using the recombinant antigen was performed on 57 sera and the antibody avidity determined. There was a highly significant correlation (P < 0.001) between the relative amounts of low avidity B19-specific IgG antibodies and time after onset of illness. This finding allows the detection of IgG to be used for diagnosing acute infection.

Antenatal survey for the seroprevalence of HTLV-1 infections in the West Midlands, England

The sera of 3522 women who attended an antenatal clinic in Birmingham, England were tested anonymously for antibodies against HTLV-1. Samples from 5 women (0.14%) were positive, one serum showed indeterminate reactivity. Two of the women (0.06%) were born in the West Indies (of Afro-Caribbean ethnic origin), one (0.03%) in Africa (of African ethnic origin), and three (0.09%) were white Caucasian women born in the UK. Thus, HTLV-1 infection in pregnant women in the UK, though comparatively rare, is not negligible. As transmission of HTLV-1 to the newborn via breast milk has been observed and as seropositive mothers can be advised to refrain from breastfeeding or to treat their milk, the question of routine screening for HTLV-1 infection during antenatal care is discussed.

Prevalence of antibodies to Norwalk virus in England: detection by enzyme-linked immunosorbent assay using baculovirus-expressed Norwalk virus capsid antigen

A total of 3,250 serum specimens collected in England in 1991 and 1992 were tested by an indirect enzyme-linked immunosorbent assay for antibody to Norwalk virus using baculovirus-expressed capsid antigen, and 2,382 (73.3%) were positive. The prevalence of Norwalk virus antibody differed regionally. It was lowest (24.6%) in 6- to 11-month-old infants and increased to 89.7% in persons over 60 years old.

Sequence analysis of reverse transcriptase genes of zidovudine (AZT)-resistant and -sensitive human immunodeficiency virus type 1 strains

Sequential isolates of human immunodeficiency virus type 1 (HIV-1) were obtained from patients with AIDS on short and long term treatment with zidovudine (3'-azido-3'-deoxythymidine; AZT). The isolates were tested for resistance to zidovudine by monitoring the inhibition of syncytium formation, HIV-1-specific immunofluorescence and p24 production in C8166 cells. The reverse transcriptase (RT) genes of zidovudine-sensitive (< 1 microM) and -resistant (10 to 15 microM) strains were amplified using the polymerase chain reaction and the products were sequenced directly. The predicted amino acid sequences of the RTs of zidovudine-sensitive and -resistant isolates showed 95 to 97% identity to the corresponding sequence of HIV-1SF2 which was used as a reference. Amino acid changes at positions 41, 67, 70, 215 and 219 which are known to be associated with zidovudine resistance were present in some, but not all isolates exhibiting zidovudine resistance in vitro. This indicates that mutations in the RT of HIV-1, other than those already identified, may be involved in conferring resistance to zidovudine.

Homotypic and heterotypic immune responses to group A rotaviruses in parenterally immunized sheep

Immune responses to human rotaviruses were investigated in sheep with a view to obtaining antibodies for passive immunotherapy of humans. Eighteen adult sheep with previous natural exposure to rotavirus serotypes G3 and G6 were immunized parenterally with purified preparations of either individual rotavirus serotypes G1, G2, G3, G4 and G8, or a mixture thereof. Two additional sheep were kept as control animals with the flock. The antibody responses were measured on serial serum samples by neutralization tests. The homotypic antibody response ranged from 100-fold (rarely) up to 100,000-fold increases in titre. Heterotypic responses against serotypes G3 and G6 were demonstrated in 7/12 and 15/18 sheep, respectively, but the increases in titre were lower than the homotypic responses, ranging from 10- to 100-fold in most cases and were 1000-fold in two sheep. Interestingly, no heterotypic response against the human rotavirus serotypes was raised after 3 months; moderate titres of cross-neutralizing antibodies for the human serotypes were only observed after a third inoculation.