Safety and Immunogenicity of Single Dose Choleragarde® in HIV-Seropositive Adults
Safety and Immunogenicity of Single Dose Choleragarde® in HIV-Seropositive Adults
The purpose of this study is to assess the safety and immunogenicity of Peru-15
 (CholeraGarde®) vaccine in HIV seropositive adult population of Bangkok Thailand
Cholera re-emerged in 2006 as a global threat with a 79% increase in 2006 compared to the
 previous year. The re-emergence of cholera increased with increasing numbers of displaced
 populations living in unsanitary conditions. About 99% of the reported cases were from Africa
 with most of the deaths reported also from this region. Case fatality rate has increased
 worldwide to 2.7% however, certain areas in Africa reported as much as 30% case fatality [WER
 2007]. These figures are believed to be underestimates and that as many as 120 000 deaths due
 to cholera are estimated to occur each year [WER 2001]. Underreporting is common due to
 inconsistencies in the definition of cholera and limitations of surveillance, however some
 countries do not report due to fear of international sanctions. In 2007, the International
 Health Regulation came into effect wherein trade and economic sanctions should no longer be
 imposed in countries reporting cholera but rather encourage open reporting so as to contain
 and prevent the spread of cholera epidemics [WER 2007].

 Provision of safe water and food, establishment of adequate sanitation, and implementation of
 personal and community hygiene constitute the main public health interventions against
 cholera. These measures cannot be fully implemented in the near future in most
 cholera-endemic areas. A safe, effective, and affordable vaccine would be a useful tool for
 cholera prevention and control.

 Considerable progress has been made during the last decade in the development of new
 generation oral vaccines against cholera. These have already been licensed in some countries
 and are now being considered for wider public health application. The World Health
 Organization recently recommended that the newer generation cholera vaccines be considered in
 certain endemic and epidemic situations, but indicated that demonstration projects are needed
 to provide more information about the costs, feasibility, and impact of using these vaccines
 [WHO Meeting 2002].

 A killed oral cholera vaccine (Dukoral™) has long been available internationally, however its
 2-dose schedule, the use of a buffer and the cost of the vaccine have long impeded its use in
 public health settings. A live oral vaccine (Orochol™), although internationally licensed is
 currently not available in the market. This vaccine is only available for use in children
 older than 6 years old and adults. Despite the immunogenicity and efficacy in challenge
 studies in North American volunteers [Tacket CO 1999], in a field trial of this vaccine in an
 endemic area in Indonesia, no protective efficacy was detected during the period of
 observation [Richie EE 1994].

 A need exists for an improved cholera vaccine that is more thermostable and may be used in
 endemic countries in younger age groups. This new generation live oral cholera vaccine must
 be administered in a single-dose regimen, be thermostable, confer high grade long-term
 protection and may be given to children below 2 years of age through mass immunization
 campaigns or through the EPI. In the Diseases of the Most Impoverished Programme (DOMI) of
 the IVI, Peru-15 (CholeraGarde®) was identified as the most promising of all the vaccine
 candidates. It is a live oral attenuated cholera vaccine derived from V. cholerae O1 El Tor
 Inaba strain that was first isolated in Peru in 1991 [Taylor DN 1994]. This has the advantage
 of having the same biotype as the current pandemic strain. Peru-15 has been attenuated by
 several genetic modifications and deletions. By the deletion of the ctx A and the rtxA genes,
 it has been rendered unable to encode for cholera toxin subunit A and RTX toxin making it
 non-toxigenic; by the inactivation of the recA gene and deletion of the attRS1 sequences, it
 has been made unable to integrate exogenous DNA making it non-recombination and by the
 absence of the potentially inflammatory flagella it has been rendered non-motile [Taylor DN
 1994, Kenner 1995]. Phase I and II studies have been performed in North American volunteers
 where it was found to be safe and immunogenic [Kenner 1995, Sack 1997] . Furthermore, the
 vaccine strain isolated from the stools of volunteers retained its non-motile characteristic.
 In a challenge study among North American volunteers, Peru-15 provided 100% protection
 against moderate and severe diarrhoea, and 93% against any diarrhoea [Cohen 2002].

 This vaccine underwent phase I and II studies in a cholera-endemic area in Matlab, Bangladesh
 in three age groups: adults aged 18 - 45 years, children aged 2 - 5 years and infants aged 9
 - 23 months [Qadri 2007]. In these studies, the vaccine has been shown to be safe and elicit
 vibriocidal responses among all age groups. Only 1 of 20 adults and 8 of 140 children vaccine
 recipients excreted the vaccine strain. Analysis of the strains isolated revealed that the
 strains remained unchanged in phenotypic and genotypic properties after passage in the stool.

 Although this vaccine can be given as a single dose, and appears to be immunogenic in
 infants, the vaccine requires stringent cold storage conditions at -20ºC. Avant
 Immunotherapeutics Inc., manufacturers of Peru-15, is currently reformulating the vaccine in
 order to make it more thermostable. In order to assess whether this vaccine is as safe and
 immunogenic as the previous formulation, this lyophilized formulation will need to undergo
 clinical testing in an endemic community.

 The International Vaccine Institute (IVI) through the Cholera Vaccine Initiative (CHOVI)
 together with Avant Immunotherapeutics Inc., manufacturers of the Peru-15 vaccine, have
 negotiated an agreement that allows clinical trials to be performed in cholera-endemic
 countries, including, India, Bangladesh, and Thailand. This will eventually enable licensure
 and facilitate the international use of this vaccine by obtaining a WHO recommendation for
 its global use. This single dose vaccine may easily be used in endemic countries and deployed
 at times when outbreaks are likely to occur.

 Because cholera tends to occur in areas where the seroprevalence of HIV is also high, safety
 and immunogenicity of any vaccine against cholera must be established among HIV infected
 individuals. There is limited data regarding the use of oral cholera vaccines among HIV
 seropositive individuals. A study in Beira, Mozambique, an area with a 20-30% HIV
 seroprevalence revealed that the killed oral rBS-WC vaccine may be effective against cholera
 [12]. However, specific data on HIV status and safety of the vaccine was not determined in
 the study. The live attenuated CVD 103 HgR vaccine was found to be equally safe among HIV
 seropositive and HIV seronegative individuals in Mali. The vaccine however was found to
 result in attenuated immune response among HIV seropositive individuals [Perry 1998].

 In order for the Peru-15 cholera vaccine to be used extensively in cholera outbreaks or in
 cholera endemic settings where HIV co-exists, safety and immunogenicity must first be
 established among HIV-seropositive individuals.

 To gain approval for use in the developing world, a single-dose of CholeraGarde® will have to
 confer high levels of protective efficacy for three years when given to endemic populations 9
 months and older. However, before undertaking a phase III efficacy trial, a series of phase
 II clinical studies need be conducted in order to confirm safety and immunogenicity of the
 vaccine. Since cholera and HIV co-exist in some areas of the world, safety and immunogenicity
 of the Peru-15 vaccine must be established among HIV seropositive individuals.
Inclusion Criteria:

 HIV-seropositive, non-pregnant adults, aged 18 - 45 years old who have been on standard
 highly active antiretroviral therapy (HAART) for at least 6 months prior to enrollment or
 who have never started HAART regimen will be recruited in the study.

 All subjects must satisfy the following criteria at study entry:

 1. Male and female HIV seropositive adults aged 18 to 45 years old who have given the
 written informed consent.

 2. Will comply with the requirements of the protocol (i.e. available for follow-up visits
 and specimen collection).

 3. CD4 T-lymphocyte count >500/mm3 for at least 6 months prior to inclusion

 Subjects that have never started HAART regimen must satisfy the following additional
 criteria at study entry.

 1. Asymptomatic HIV infection as determined by: Medical history, Physical examination,
 Laboratory tests, Clinical judgment of the investigator

 Subjects that have been on standard highly active antiretroviral therapy (HAART) for at
 least 6 months prior to enrollment must satisfy the following additional criteria at study
 entry.

 1. History of CD4 nadir >150/mm3

 2. Viral load (HIV-1 RNA levels) <200 copies/mL for at least 6 months prior to inclusion

 Exclusion Criteria:

 The following criteria should be checked at the time of study entry, if any of the
 following is present then the subject will be excluded from the study:

 1. Overt signs of immunodeficiency e.g. oral thrush, rapid weight loss, recurrent
 pneumonia (i.e. Stage 3 or 4 of the WHO clinical staging system for HIV infection and
 disease in adults and adolescents

 2. Ongoing serious chronic illness (e.g. with signs of cardiac or renal failure)

 3. Abdominal pain or cramps, loss of appetite, nausea, general ill-feeling or vomiting in
 the past 24 hours

 4. Presence of V. cholerae 01 or 0139, Shigella, or Cryptosporidium in stool at baseline

 5. Intake of any anti-diarrhoeal medicine in the past week

 6. Acute disease one week prior to enrollment, with or without fever. Temperature ≥38ºC
 (oral or otic) warrants deferral of the vaccination pending recovery of the subject

 7. Receipt of antibiotics in the past 2 weeks

 8. Receipt of live or killed enteric vaccine in the last 4 weeks

 9. Receipt of killed oral cholera vaccine in the past

 10. Diarrhea (3 or more loose stools within a 24-hour period) 6 weeks prior to enrollment

 11. One or more episodes of diarrhea lasting for more than 2 weeks in the past 6 months

 12. One or more episodes of abdominal pain lasting for more than 2 weeks in the past 6
 months

 13. Receipt of blood, blood products or a parenteral immunoglobulin preparation in the
 previous 6 months

 14. Receipt of any immunosuppressive therapy during the past 6 months

 15. A woman pregnant or planning to become pregnant during the period of subject's
 participation

 16. Any condition which in the opinion of the investigator, might interfere with the
 evaluation of the study objectives