Plaque and growth characteristics of different polioviruses isolated from acute flaccid paralysis in Northern Nigeria.

OBJECTIVE: To determine some virulent trait-related properties of poliovirus isolates from children with acute flaccid paralysis following vaccination with oral polio vaccine (OPV). DESIGN: Six polioviruses earlier characterised into wild, vaccine-derived and OPV-like were studied using the plaque morphology and growth kinetics at supra-optimal temperature. SETTING: Department of Virology, University of Ibadan, Nigeria. SUBJECTS: Polio isolates from six children who developed acute flaccid paralysis following vaccinations with various doses of OPV were used. All the children were located in the Northern part of the country where poliovirus is still circulating. MAIN OUTCOME MEASURES: The two vaccine-derived polioviruses acquired wild type characteristics. RESULTS: All the six poliovirus isolates developed different forms of plaques ranging from tiny, small and large. The plaque formed could however not be used to identify the different isolates. Growth of the different isolates at supra-optimal temperature showed that the three wild polioviruses grew to a higher titre when compared with the Sabin 2 control. The two vaccine derived isolates behaved like the wild poliovirus while the OPV-like virus acquired an intermediate characteristics between wild and sabin. CONCLUSION: The wild polioviruses represented in this study are among the last vestiges of the circulating polioviruses found in the world. It is possible that the observed biological properties of wild types 1 and 3 described in the study are typical of the West African polioviruses. These properties will provide useful previews to the final identification of some important clinical isolates especially type 1 which may grow rapidly in cell culture.

Antibody response to 17D yellow fever vaccine in Ghanaian infants.

OBJECTIVES: To assess the seroresponses to yellow fever vaccination at 6 and 9 months of age; assess any possible adverse effects of immunization with the 17D yellow fever vaccine in infants, particularly at 6 months of age. METHODS: Four hundred and twenty infants who had completed BCG, OPV and DPT immunizations were randomized to receive yellow fever immunization at either 6 or 9 months. A single dose of 0.5 ml of the reconstituted vaccine was administered to each infant by subcutaneous injection. To determine the yellow fever antibody levels of the infants, each donated 1 ml whole blood prior to immunization and 3 months post-immunization. Each serum sample was titred on Vero cells against the vaccine virus. FINDINGS: The most common adverse reactions reported were fever, cough, diarrhoea and mild reactions at the inoculation site. The incidences of adverse reactions were not statistically different in both groups. None of the pre-immunization sera in both age groups had detectable yellow fever antibodies. Infants immunized at 6 months recorded seroconversion of 98.6% and those immunized at 9 months recorded 98% seroconversion. The GMT of their antibodies were 158.5 and 129.8, respectively. CONCLUSIONS: The results indicate that seroresponses to yellow fever immunization at 6 and 9 months as determined by seroconversion and GMTs of antibodies are similar. The findings of good seroresponses at 6 months without significant adverse effects would suggest that the 17D yellow fever vaccine could be recommended for use in children at 6 months in outbreak situations or in high risk endemic areas.

Comparison of AIK-C measles vaccine in infants at 6 months with Schwarz vaccine at 9 months: a randomized controlled trial in Ghana.

In a randomized controlled trial in a measles endemic area, standard-dose (4.0 log10pfu) AIK-C measles vaccine administered at 6 months of age was compared to standard-dose Schwarz vaccine (3.7log10pfu) given at 9 months. Seroconversion rates at 3 and 6 months after immunization in the two groups were comparable and similar. The geometric mean titres achieved were, however, significantly higher in the Schwarz group (P < 0.05). No immediate serious side-effects were observed with either vaccine. We conclude that standard-dose AIK-C measles vaccine can be recommended for measles immunization in children below 9 months of age, especially in highly endemic and high-risk areas in developing countries.

PIP: The seroresponse of standard-dose heat-stable AIK-C measles vaccine administered to infants at 6 months of age was compared to that of standard-dose Schwarz vaccine administered at 9 months of age in a measles-endemic area in West Africa. The study was conducted in Asamankese, the capital town of Ghana's East Akim District. Infants 24-27 weeks of age who had been attending the Asamankese maternal-child health clinic regularly and had received all the required immunizations were enrolled and randomly assigned to receive the AIK-C (n = 184) or the Schwarz (n = 193) vaccine. No severe adverse reactions were reported during the 10-day follow-up period in either vaccine group. In the AIK-C group, 96.9% of infants who were seronegative at preimmunization and 79.4% of those with preexisting antibodies had seroconverted by 3 months after immunization; at 6 months after immunization, these rates were 97.3% and 100%, respectively. In the Schwarz group, 98.2% of infants seronegative at immunization and 100% of those with preexisting antibodies seroconverted by 3 months after immunization; at 6 months, these rates were 99.1% and 80%, respectively. Although the geometric mean titres achieved were significantly higher in the Schwarz vaccine group, these titres were above the protective level of 200 mIU in the AIK-C group. Administration of measles vaccine at a younger age may be more easily incorporated into current Expanded Program on Immunization schedules.

Wild polio virus surveillance in the sewage system of selected communities at the risk of poliomyelitis in southwest Nigeria.

Twenty two sewage samples collected from eleven locations among communities at risk of poliomyelitis in the southwestern part of Nigeria were screened for the presence of polio virus. The virus was isolated from seven of the samples. All the isolates were type 1 wild polio virus, an indication that all the isolates were from human contamination and that the wild polio virus is still very much in circulation in Nigeria many years after the Expanded Programme on Immunisation was introduced. It can be concluded from this study that polio immunisation campaign has not been successful in Nigeria considering the number of wild polio virus isolated from the sewage samples since virological examination of sewage has been used to document the effect of vaccination campaigns.

Surface marker patterns of T cells and expression of interleukin-2 receptor in measles infection.

The surface marker patterns of T cells of Ghanaian children during measles infection were studied and an attempt was made to demonstrate T cell activation and viability in vitro after activation in vivo by measles virus. The frequencies of CD4+ and CD8+ naive T cells in measles patients were high while their memory T cells were remarkably reduced with no sign of proliferation even at the acute phase of the illness. The reduction of memory T cells was prolonged during the convalescent phase (2 months after onset). The anti-CD3 monoclonal antibody-induced expression of interleukin-2 receptor alpha chain (IL-2R/CD25) was significantly suppressed; however, the addition of phorbol 12-myristate 13-acetate or ionomycin caused a remarkable recovery of CD25 expression. On simple culture, an appreciable proportion of T cells from measles patients died rapidly in contrast with only a few T cells from healthy controls doing so. The suppression of CD25 expression was still demonstrated during the convalescent phase of the disease. Taken together these results suggest unresponsiveness and activation-induced cell death of T cells during severe measles infection in Ghanaian children. Furthermore the prolonged abnormalities of T cells (i.e. decreased memory T cells and inhibition of CD25 expression during the convalescent phase) might be related to post-measles infection immunosuppressive status.

Phylogenetic analysis of human immunodeficiency virus 1 in Ghana.

Eleven human immunodeficiency virus 1 (HIV-1) isolates from Ghanaian acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) patients obtained by our serosurvey in 1986-1994 were genomically analyzed and phylogenetically compared with other known strains. A phylogenetic tree constructed by analyzing the env region indicated that heterogeneous HIV-1 strains were circulating in Ghana and the majority of them (9 of 11 isolates) belonged to clade (subtype) A which is now furiously epidemic in Africa. Another isolate (1 of 11) belonged to clade D, and the remaining one (1 of 11) belonged to "clade G". This "clade G" virus grouped by the env analysis belonged to clade A by its pol sequence, suggesting an A/G intersubtype recombinant. The characteristic sequences in the V3 tip which have not yet been reported were observed in these Ghanaian isolates, which should be taken into account for future vaccine programs.

PIP: The molecular epidemiology of HIV-1 in Ghana was investigated through genomic and phylogenetic analysis of isolates from 11 AIDS or AIDS-related complex patients obtained in 1986-94. A phylogenetic tree constructed by analyzing the env region indicated that heterogeneous HIV-1 strains are circulating in Ghana. 9 of the isolates belonged to clade A, 1 to subtype D, and 1 to "clade G"--an A/G intersubtype recombinant. The V3 loops of all isolates were composed of 35 amino acid residues--a characteristic not previously described. These molecular data on the genetic variability of the envelope glycoprotein of HIV-1 should be useful for future vaccine studies in West Africa.

Predominance of HIV-1 among patients with AIDS and AIDS-related complex in Ghana.

We determined the prevalence of HIV among AIDS and AIDS-Related Complex (ARC) patients seen within one year in two hospitals in southern Ghana. Subjects were screened by an ELISA procedure for anti-HIV antibodies. Specific identification of the HIV type was done with a particle agglutination (PA) kit. All PA-determined dual specimens were then confirmed by Western blotting and Pepti-Lav 1/2 monoepitope kit. Virus isolation was attempted from symptomatic patients by co-culturing patient peripheral blood monocyte cells (PBMCs) and CD4+ cell lines. PBMCs and HIV isolates were characterised by PCR. By ELISA, 43.5% of the subjects (253) had anti-HIV antibodies. Of these, 61 (24%) were HIV-1 positive and 42 (18.6%) were dually reactive by PA. However, only 19% were confirmed as true dually-infected cases by western blotting and Pepti-Lav through all 42 samples were HIV-1 positive on the two tests. No subject was infected with HIV-2 alone. Three viruses were isolated. By PCR two of them had both HIV-1 and HIV-2 proviral sequences while the third virus was HIV-1 only. HIV-1 prevalence now predominates over HIV-2 implying a switch in the HIV infection pattern in Ghana. Furthermore mixed infections exist. The predominance of HIV-1 infection in Ghana may indicate a similar trend in other parts of West Africa.

PIP: Recent studies have suggested that HIV-2 infection is becoming less prevalent in Ghana, while the prevalence of HIV-1 is increasing. To confirm such a modification in the HIV infection profile in Ghana, a 1-year serologic and molecular study was conducted among 253 patients from 2 hospitals in southern Ghana (Accra and Dzodze in the Volta region) with confirmed or suspected AIDS. All 253 serum specimens were screened with enzyme-linked immunosorbent assay (ELISA) and particle agglutination (PA); the 42 dually reactive specimens were subsequently confirmed by Western blot and Pepti-Lav tests. By ELISA, 110 samples (43.5%) were positive for anti-HIV antibodies; this rate was 39.2% in Accra and 81.0% in the Volta region. Of these, 61 (24.1%) were HIV-1 positive and 42 (18.6%) were dually reactive by PA. No case of HIV-2 alone was detected. Most dually reactive cases were a cross-reaction between genetically similar regions of the 2 HIV types. Only 19% of the 42 PA-diagnosed dually reactive specimens were confirmed by Western blot and Pepti-Lav as true cases of HIV-2 only infection, and all these specimens were strongly positive for anti-HIV-1 antibodies. 3 viruses were isolated. By polymerase chain reaction, 2 had both HIV-1 and HIV-2 proviral sequences, while the third was HIV-1 only. This study's findings provide support for the hypothesis that most individuals with antibodies to both HIV-1 and HIV-2 are probably infected with HIV-1 alone. Intensified population surveillance aimed at isolating more HIV strains in West Africa could reveal the true extent of HIV genomic variation and facilitate the design of more specific diagnostic kits.

Genetic and phylogenetic analysis of HIV type 1 env subtypes in Ghana, west Africa.

PIP: The authors examined HIV-1 genetic variation among 19 HIV-1-infected people of mean age 34.5 years living in Accra, Akwatia, Kumasi, and Ho, in Ghana. One person was of unknown origin. Blood samples were collected between December 1993 and January 1996. 16 of the HIV-1 specimens clustered with members of subtype A, but the clustering was not supported by 70% or more of the bootstrap tests. Two samples clustered with subtype D strains, supported by 92.5% of the bootstrap trees, and one sample clustered with subtype G strains, supported by 96.2% of the bootstrap trees. For the Ghanaian specimens belonging to subtype A, interhost distances at the nucleotide level averaged 14.9%, of range 7.83-20.9%. The interhost distance between the two subtype D samples was 8.2%. A cocirculation of subtypes A, D, and G was identified in Akwatia.^ieng

Randomized, controlled trial of trivalent oral poliovirus vaccine (Sabin) starting at birth in Ghana.

To evaluate the efficacy of the schedule currently recommended for immunization with trivalent oral poliovirus vaccine (TOPV) (i.e., at birth, 6 weeks, 10 weeks, and 14 weeks after birth), we randomly assigned 452 infants into test (231 infants) and control (221 infants) groups. The test group received TOPV as currently recommended, and the dose at birth was omitted for the control group. At 10, 14, and 18 weeks of age, the levels of poliovirus neutralizing antibodies as well as seroconversion rates were consistently higher for the test group than for the control group. The final seroconversion rates against poliovirus types 1, 2, and 3 were 83.5%, 91% and 83%, respectively, for the test group and 75%, 83.2%, and 79.1%, respectively, for the control group. The TOPV immunization schedule starting at birth therefore produced better results. Seroconversion rates as well as antibody levels were highest in infants with low maternal antibodies.

Serological survey of HIV-1, HIV-2 and human T-cell leukemia virus type 1 for suspected AIDS cases in Ghana.

OBJECTIVE: To determine seroprevalence among suspected AIDS patients in Ghana in relation to clinical manifestations. MATERIALS AND METHODS: Blood samples and medical records were collected from 290 Ghanaian patients with suspected AIDS in 1990 and 1992. Seroprevalence of HIV-1, HIV-2 and human T-cell leukemia virus (HTLV-1) were investigated by the particle agglutination method, indirect immunofluorescence assay, the monoepitope enzyme-linked immunosorbent assay and Western blot. RESULTS: The specimens were classified into five serologic categories: 78 were HIV-1-positive (26.9%), 25 were HIV-2-positive (8.6%), 17 dual-positive (5.9%), 16 indeterminate (5.5%) and 154 seronegative (53.1%). No significant difference was found between the clinical symptoms of patients with HIV-1 and HIV-2 infection. Of the patients, 14 (4.8%) were HTLV-1-seropositive, of whom 11 were also HIV-positive, indicating a significant correlation between the two groups of viral infections (P < 0.01). However, there was no evidence of an increase in severity of symptoms in cases of dual infection with HTLV-1 and HIV. CONCLUSIONS: HIV-1 infection is now dominant in Ghana in contrast to our previous survey in 1986 which showed the dominance of HIV-2. The change in seroprevalence suggests that an HIV-1 epidemic has been developing in recent years in this country, where HIV-2 was originally endemic. A relatively high prevalence of dual-reactive specimens implies the existence of highly cross-reactive strains of HIV or frequent coinfection with HIV-1 and HIV-2 in the region. The large number of seronegative patients with clinically diagnosed AIDS raises the question of the inadequacy of AIDS definitions based on clinical manifestations only.

Isolation and genomic analysis of human T lymphotropic virus type II from Ghana.

An HTLV-II was isolated from a Ghanaian female patient with ARC and anti-HTLV-II antibody by cocultivation of PBMC with Molt-4 cells. A part of the 5' LTR of this virus was sequenced. Sequence homology between this virus and the corresponding sequence of Mo, the prototype of HTLV-II, is 97.4%. Furthermore, this virus is a member of the HTLV-IIa group, which was proposed by Hall et al. This is the first report of an HTLV-II sequence from Africa confirmed not only by serological evidence, but also by genomic analysis. This finding will provide useful information for considering the spread of HTLV-II in the world and the evolution of the HTLV group.

Isolation and characterization of a highly divergent HIV-2[GH-2]: generation of an infectious molecular clone and functional analysis of its rev-responsive element in response to primate retrovirus transactivators (Rev and Rex).

A highly divergent HIV-2 designated as HIV-2[GH-2] was obtained from an AIDS-related complex (ARC) patient in Ghana. A full-length molecular clone of this isolate was obtained and a biologically active clone was constructed. Its restriction pattern differed from that of prototype HIV-2[GH-1] in 25 of 35 restriction sites, but was strikingly similar to a previously characterized HIV-2 isolate from a Ghanaian (HIV-2ALT). The conserved integrase region (288-bp fragment) previously displayed 95% identity with that of ALT but 17-20% divergence from the HIV-2 prototype member, and a new distinct subgroup (HIV-2b) of HIV-2 consisting of GH-2 and ALT was postulated (Miura et al. 1991.) These isolates, however, were biologically distinguishable from each other by its replication capacity in a monocyte line, U937, in which GH-2 could not grow but ALT grew well. In addition, the nucleotide sequence of the LTR of this new isolate displays 21% divergence from that of prototype HIV-2[GH-1], but the core enhancer, Sp1 binding sites and TATA box were conserved. Although the 3' half of the env gene sequence which is deleted in HIV-2ALT clone showed 27% diversity from the prototype, functional differences in the rev-responsive element were not observed.

Epidemic acute haemorrhagic conjunctivitis due to Coxsackie virus A24 variant in Ghana.

An outbreak of acute haemorrhagic conjunctivitis (AHC) occurred in Accra, Ghana, reaching a peak in July 1987. Individuals ranging from infants to adults over 50 years were infected, with those between 20 and 30 years being the most affected group. There was a female preponderance. Clinical features included conjunctivitis, subconjunctival haemorrhage and ocular pain. Some patients reported of blurred vision due to mild keratitis. Isolation of virus from clinical specimens of AHC patients was successful only in cells of human origin such as HeLa and FL. Coxsackie virus A24 variant (CA 24v) was identified as the aetiologic agent. This is the first report to associate CA 24v with an epidemic of AHC in Africa, south of the Sahara, which is outside the endemic area of Southeast Asia and the Caribbeans. This finding suggests that earlier outbreaks of AHC in Ghana and Africa may have been due to CA 24v but went undetected. The results of various tests performed during this study suggest that, at least, two antigenically different viruses of CA 24v circulated during the course of this epidemic.

Two dose immunization trial with the trivalent oral poliomyelitis vaccine (TOPV) in Ghana

The Virology Unit of Noguchi Memorial Institute for Medical Research in a pilot study has tried by doubling the dose volume; a two dose immunization scheme; which when started at birth; is completed in the sixth week of life